WO2010026757A1 - Transmitter, receiver, optical transmission system, and optical transmission method - Google Patents
Transmitter, receiver, optical transmission system, and optical transmission method Download PDFInfo
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- WO2010026757A1 WO2010026757A1 PCT/JP2009/004349 JP2009004349W WO2010026757A1 WO 2010026757 A1 WO2010026757 A1 WO 2010026757A1 JP 2009004349 W JP2009004349 W JP 2009004349W WO 2010026757 A1 WO2010026757 A1 WO 2010026757A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/548—Phase or frequency modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0278—WDM optical network architectures
- H04J14/0279—WDM point-to-point architectures
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0254—Optical medium access
- H04J14/0256—Optical medium access at the optical channel layer
- H04J14/026—Optical medium access at the optical channel layer using WDM channels of different transmission rates
Definitions
- the present invention relates to a method of multiplexing a plurality of signals on one wavelength of light, and more particularly to a transmission device, a reception device, an optical transmission system, and an optical transmission method for transmitting a low-speed signal superimposed on a high-speed phase modulation signal.
- the optical fiber communication system has become an important technology for realizing long-distance and large-capacity communication.
- Large-capacity communication is realized using modulation / demodulation devices used for transmission and reception, and the broadband characteristics of optical fibers serving as transmission paths.
- modulation / demodulation devices used for transmission and reception
- broadband characteristics of optical fibers serving as transmission paths Taking advantage of this characteristic, in recent years, many technologies capable of realizing an optical transmission system having an interface capacity of 100 Gbps (gigabits per second) have been realized.
- time division multiplexing systems and wavelength division multiplexing systems have been used as means for aggregating low-speed signals using an optical fiber communication system and realizing large capacity transmission in one system.
- a transmitter In an optical transmission system using time division multiplexing, a transmitter generates a high-speed electrical signal by electrically multiplexing a group of low-speed signals synchronized in frequency, and modulates and transmits light using the high-speed electrical signal. The method to do is adopted. Further, the receiving apparatus detects the modulated light, discriminates and reproduces it, and separates it in the time division direction, thereby separating the multiplexed signal and reproducing the original low-speed signal group.
- high-speed signals can be generated using electrical multiplexing, and optical devices that occupy most of the system cost can be one set of transmission and reception. Has the advantage of being possible.
- a transmission device uses a plurality of optical transmission units having light sources that oscillate at different signal wavelengths, and outputs light output from these optical transmission units to a plurality of electrical signals. Modulate with.
- the transmission apparatus multiplexes a plurality of modulated lights using a wavelength multiplexing circuit and transmits the multiplexed light on one fiber.
- the receiving apparatus a plurality of wavelengths are individually separated using an optical separation circuit, and then a signal is detected and identified and reproduced using a plurality of receiving units. In this method, multiplexing is possible even if the low-speed signal has a different method and format.
- the first is a measure against optical noise accumulation.
- the signal band to be used increases, and the amount of noise received by the system also increases.
- the value of the signal-to-noise ratio in the receiving apparatus becomes small, resulting in a quality deterioration in which code errors increase.
- the transmission distance is increased, it is necessary to increase the number of optical amplification repeaters for loss compensation. Due to the accumulation of optical noise generated by this optical amplification repeater, the signal-to-noise in the receiving apparatus is increased. Ratio degradation occurs. Therefore, in order to realize high speed and long distance, it is necessary to reduce the accumulation of optical noise or develop a transmission system that is strong against optical noise accumulation.
- phase modulation method particularly a differential phase shift keying (DPSK) method has attracted attention for such a problem of optical noise accumulation (for example, Patent Document 1).
- the differential phase shift keying method is a method in which the phase of light in adjacent bit slots is changed by ⁇ in order to transmit digital signals 1 and 0.
- a system in which a 1-bit delay detection reception system is combined with a phase modulation system has attracted attention due to the advantages of high performance and simple configuration.
- the transmission apparatus changes the phase of the bit slot by ⁇ , and when the transmission data is 0, the optical phase remains unchanged.
- the receiving apparatus distributes the received signal to two branches having one-bit delay elements arranged on one side, and then causes the two signals to interfere with each other.
- the receiving apparatus converts the information applied to the phase change into intensity information and receives it.
- a plurality of very high-speed electrical signals can be flexibly multiplexed, for example, even asynchronous signals can be multiplexed.
- the multiple signals are accommodated in a single wavelength slot as much as possible.
- wavelength division multiplexing it is generally difficult to accommodate a plurality of signals in a single wavelength slot.
- the bandwidth of the wavelength slot it is possible to perform wavelength multiplexing within one wavelength slot by multiplexing a plurality of peaks with high density, but monitoring a signal having a plurality of such peaks. Therefore, it is preferable that the spectrum is as unimodal as possible.
- the phase modulation method a plurality of electric signals cannot be multiplexed by the conventional methods.
- the present invention has been made in order to solve the above-described problems.
- the purpose of the present invention is to multiplex a plurality of signals having different speeds, multiplex information with a single peak spectral shape in a single wavelength slot, and
- An object of the present invention is to provide a transmission device, a reception device, an optical transmission system, and an optical transmission method that can be implemented by adding necessary parts to the system.
- a transmission apparatus is a transmission apparatus that multiplexes two signals having different speeds into one optical signal and transmits the multiplexed signal.
- a high-speed signal output unit that outputs a signal
- a high-speed signal phase modulation unit that performs phase modulation with a phase shift amount ⁇ in accordance with the first signal, and a second signal that is slower than the first signal
- a low-speed signal output unit that outputs a signal
- a low-speed signal modulation unit that performs phase modulation or frequency modulation of an optical signal output from the high-speed signal phase modulation unit based on the second signal, and an output from the low-speed signal modulation unit
- a transmitter that transmits the optical signal thus received to the receiver.
- the receiving apparatus of the present invention is a receiving apparatus that receives one optical signal obtained by multiplexing two signals having different speeds, and performs phase modulation with a phase shift amount ⁇ according to the first signal. From an optical branching unit for branching an optical signal that has been phase-modulated or frequency-modulated based on a second signal that is slower than the first signal from a transmitter, and delay interference of the one branched optical signal A delay interference unit that outputs interference light, a light detection unit that converts the interference light into an electrical signal, a rectification unit that full-wave rectifies the electrical signal, and the first signal based on the full-wave rectified electrical signal.
- the optical transmission system of the present invention includes the transmitting apparatus of the present invention and the receiving apparatus of the present invention.
- the optical transmission method of the present invention is an optical transmission method in which two signals having different speeds are multiplexed and transmitted in one optical signal, and the first signal is output in accordance with the first signal. , Output a phase-modulated optical signal by performing phase modulation with a phase shift amount of ⁇ , output a second signal slower than the first signal, and based on the second signal, Phase modulation or frequency modulation of the phase-modulated optical signal is performed and transmitted to the receiver.
- the optical transmission method of the present invention is an optical transmission method for receiving one optical signal obtained by multiplexing two signals having different speeds, and performs phase modulation with a phase shift amount ⁇ according to the first signal.
- the first signal is obtained based on the signal.
- the transmitting apparatus superimposes the second signal, which is slower than the first signal, on the optical signal phase-modulated according to the first signal by using phase modulation or frequency modulation.
- the receiving apparatus performs delayed interference on the optical signal from the transmitting apparatus, converts the interference light into an electrical signal, and acquires the second signal based on the electrical signal that has been full-wave rectified. Further, the receiving device performs phase modulation on the optical signal from the transmitting device based on the optical signal from the transmitting device (for example, by receiving the optical signal from the transmitting device or according to the acquired second signal). Alternatively, the first signal is reproduced (by receiving after frequency modulation). Thereby, the first signal and the second signal can be multiplexed.
- the transmitting apparatus superimposes the first signal and the second signal using optical signals having the same wavelength.
- the multiplexed signal becomes a unimodal spectrum, and a plurality of signals can be stored in a single wavelength slot.
- the transmission device performs phase modulation according to the first signal by the high-speed signal phase modulation unit, and performs phase modulation or frequency modulation based on the second signal by the low-speed signal modulation unit. Accordingly, it is possible to easily implement by adding a necessary part to an existing optical transmission system, such as adding a low-speed signal modulation unit when necessary.
- the transmission apparatus since the transmission apparatus performs superimposition of the second signal by phase modulation or frequency modulation, the intensity of the phase modulation signal corresponding to the first signal is not lost.
- the second signal since the second signal is removed from the superimposed signal by reproducing the second signal by the receiving device, information on the light intensity is not lost. As a result, the second signal can be multiplexed without greatly losing the long-distance transmission characteristic of the phase-modulated signal corresponding to the first signal.
- FIG. 1 is a schematic block diagram showing a configuration of an optical transmission system according to a first embodiment of the present invention. It is a phase diagram which shows the transition of the phase of the optical signal accompanying the phase modulation of a high-speed signal phase modulation part. It is a phase diagram which shows the transition of the phase of the optical signal accompanying the phase modulation of a low-speed signal phase modulation part.
- A is a figure which shows the transition of the phase of the optical signal which the high-speed signal phase modulation part in 1st Embodiment outputs
- (b) is the phase of the optical signal which the low-speed signal phase modulation part in 1st Embodiment outputs.
- FIG. 4C is a diagram illustrating a voltage transition of an electric signal output from the light detection unit in the first embodiment
- FIG. 4D is a diagram illustrating an electric signal output from the rectification unit in the first embodiment. It is a figure which shows voltage transition. It is a schematic block diagram which shows the structure of the optical transmission system according to the 2nd Embodiment of this invention.
- (A) is a figure which shows the transition of the bit of the signal which the low-speed signal output part in 2nd Embodiment outputs
- (b) is a figure which shows the transition of the bit of the signal which the precoding part in 2nd Embodiment outputs
- (C) is a figure which shows the transition of the phase of the optical signal which the low-speed signal phase modulation part in 2nd Embodiment outputs
- (d) is the voltage of the electric signal which the photon detection part in 2nd Embodiment outputs.
- (e) is a figure which shows the transition of the voltage of the electric signal which the rectification
- FIG. 8C is a diagram showing the transition of the voltage of the electric signal output by the light detection unit in the third embodiment
- FIG. 10D is the electric signal output by the rectification unit in the third embodiment. It is a figure which shows voltage transition. It is a schematic block diagram which shows the structure of the optical transmission system according to the 4th Embodiment of this invention.
- FIG. 1 It is a schematic block diagram which shows the structure of the rectification
- FIG. 1 is a schematic block diagram showing a configuration of an optical transmission system according to the first embodiment of the present invention.
- the optical transmission system includes a transmission device 100 and a reception device 200.
- the transmission device 100 includes a light source unit 101, a high-speed signal output unit 102, a low-speed signal output unit 103, a high-speed signal phase modulation unit 104, a low-speed signal phase modulation unit 105, and a transmission unit 106.
- the low-speed signal phase modulation unit 105 corresponds to the low-speed signal modulation unit of the present invention.
- the light source unit 101 emits CW (Continuous Wave) light.
- CW Continuous Wave
- the high-speed signal output unit 102 outputs a digital signal having a predetermined frequency (first signal: hereinafter referred to as a high-speed signal).
- the high-speed signal output unit 102 outputs, for example, a 40 Gbps signal.
- the low speed signal output unit 103 outputs a digital signal having a frequency lower than that of the high speed signal (second signal: hereinafter referred to as a low speed signal).
- the low-speed signal output unit 103 outputs a signal of 10 Gbps, for example.
- the high-speed signal phase modulation unit 104 performs phase modulation of CW light according to the high-speed signal.
- the low-speed signal phase modulation unit 105 performs phase modulation of the optical signal phase-modulated by the high-speed signal phase modulation unit 104 according to the low-speed signal.
- the transmission unit 106 transmits the optical signal subjected to phase modulation by the high-speed signal phase modulation unit 104 and the low-speed signal phase modulation unit 105 to the reception device 200.
- the receiving apparatus 200 includes an optical branching unit 201, a delay interference unit 202, a light detecting unit 203, a rectifying unit 204, a low-speed signal decoding unit 205, a phase modulating unit 206, and a high-speed optical receiving unit 207.
- the low speed signal decoding unit 205 corresponds to the low speed signal acquisition unit of the present invention.
- the phase modulation unit 206 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
- the optical branching unit 201 acquires an optical signal from the transmission apparatus 100, branches the acquired optical signal, and distributes the optical signal to the delay interference unit 202 and the phase modulation unit 206.
- the optical branching unit 201 distributes an optical signal using, for example, an optical coupler.
- the delay interference unit 202 outputs interference light obtained by superimposing the distributed optical signal and the optical signal obtained by delaying the optical signal.
- a Mach-Zehnder delay interferometer or the like is used for the delay interference unit 202.
- the light detection unit 203 converts the optical signal output from the delay interference unit 202 into an electrical signal.
- the rectification unit 204 performs full-wave rectification on the electrical signal converted by the light detection unit 203.
- the low-speed signal decoding unit 205 decodes the full-wave rectified electrical signal to obtain a low-speed signal.
- the low-speed signal decoding unit 205 performs decoding by changing the pulse level of the output signal at the falling edge of the pulse of the input electric signal.
- a toggle flip-flop is used for the low-speed signal decoding unit 205.
- the phase modulation unit 206 performs phase modulation on the optical signal distributed from the optical branching unit 201 according to the low-speed signal acquired by the low-speed signal decoding unit 205. At this time, the phase modulation unit 206 performs phase modulation with a logic opposite to that of the low-speed signal phase modulation unit 105 of the transmission apparatus 100.
- the phase modulation with the logic opposite to that of the low-speed signal phase modulation unit 105 indicates the following.
- the phase modulation unit 206 when the same signal is input to the low-speed signal phase modulation unit 105 and the phase modulation unit 206, the phase modulation unit 206 outputs the optical signal output from the low-speed signal phase modulation unit 105 and the light output from the phase modulation unit 206 itself. Phase modulation is performed so that the difference in phase shift from the signal is ⁇ .
- the high-speed optical receiver 207 receives the optical signal phase-modulated by the phase modulator 206 and acquires a high-speed signal.
- a circuit combining a photodetection circuit and a phase modulation decoding circuit is used for the high-speed optical receiver 207.
- the high-speed signal phase modulation unit 104 of the transmission apparatus 100 outputs an optical signal obtained by phase-modulating the CW light output from the light source unit 101 in accordance with the high-speed signal output from the high-speed signal output unit 102.
- the low-speed signal phase modulation unit 105 phase-modulates the optical signal output from the high-speed signal phase modulation unit 104 according to the low-speed signal output from the low-speed signal output unit 103.
- the transmission unit 106 transmits the optical signal output from the low-speed signal phase modulation unit 105 to the reception device 200.
- the delay interference unit 202 of the receiving apparatus 200 performs delay interference of one optical signal branched by the optical branching unit 201 and outputs interference light.
- the low-speed signal decoding unit 205 acquires a low-speed signal from the electric signal converted from the interference light by the light detection unit 203 and full-wave rectified by the rectification unit 204.
- the phase modulation unit 206 phase-modulates the other optical signal branched by the optical branching unit 201 according to the low-speed signal acquired by the low-speed signal decoding unit 205.
- the high-speed optical receiver 207 receives the optical signal phase-modulated by the phase modulator 206 and acquires a high-speed signal.
- the optical transmission system multiplexes a plurality of signals having different velocities with a unimodal spectrum shape in a single wavelength slot.
- FIG. 2 is a phase diagram showing the transition of the phase of the optical signal accompanying the phase modulation of the high-speed signal phase modulation unit 104.
- the horizontal axis in FIG. 2 indicates the magnitude of the in-phase component of the optical signal, and the vertical axis indicates the magnitude of the quadrature component of the optical signal.
- the optical signal phase-modulated by the high-speed signal phase modulation unit 104 with the phase shift amount being ⁇ becomes a signal whose phase transitions between two points of 0 and ⁇ , as shown in FIG. That is, the phase transitions on the in-phase component axis.
- FIG. 3 is a phase diagram showing transition of the phase of the optical signal accompanying the phase modulation of the low-speed signal phase modulation unit 105.
- the horizontal axis in FIG. 3 indicates the magnitude of the in-phase component of the optical signal, and the vertical axis indicates the magnitude of the quadrature component of the optical signal.
- the low-speed signal phase modulation unit 105 When the low-speed signal phase modulation unit 105 further phase-modulates the optical signal output from the high-speed signal phase modulation unit 104 with a phase shift amount of ⁇ / 2, the modulated signal has a phase of 0 as shown in FIG. It becomes a signal that transitions at four points of ⁇ / 2, ⁇ , and 3 ⁇ / 2. At this time, the phase transition of the high-speed signal is switched between the phase transition on the in-phase component axis and the phase transition on the orthogonal component axis in response to the switching of the low-speed signal.
- the transmission unit 106 transmits the optical signal to the reception device 200.
- the optical branching unit 201 of the receiving device 200 acquires the optical signal from the transmitting device 100
- the optical branching unit 201 branches the acquired optical signal into two, and outputs them to the delay interference unit 202 and the phase modulation unit 206.
- the delay interference unit 202 performs delay interference of one of the branched optical signals.
- the delay amount is one symbol time of the high-speed signal. Accordingly, the optical signal output from the delay interference unit 202 has a light intensity when the phase difference is 0, a light intensity when the phase difference is ⁇ / 2 or 3 ⁇ / 2, and a phase difference of ⁇ . It becomes an optical signal having three kinds of light intensities.
- the phase difference becomes ⁇ / 2 or 3 ⁇ / 2.
- the delay interference unit 202 outputs an optical signal
- the light detection unit 203 converts the optical signal into an electrical signal.
- the light detection unit 203 sets the voltage of the electric signal to V when the intensity of the optical signal is the intensity when the phase difference is 0, and when the intensity is when the phase difference is ⁇ / 2 or 3 ⁇ / 2.
- the voltage of the electric signal is 0 and the intensity is when the phase difference is ⁇ , the voltage of the electric signal is ⁇ V.
- the rectification unit 204 performs full-wave rectification on the electrical signal output from the light detection unit 203.
- an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203 is output.
- the voltage becomes 0 when the symbol logic of the low-speed signal is switched, and the voltage becomes V otherwise.
- the low-speed signal decoding unit 205 performs the full-wave rectification of the electric signal (after removing high-speed waveform fluctuations associated with bit changes of the high-speed signal, as will be described later). Decoding is performed by changing the pulse level of the output signal at the falling edge of the pulse. The output signal thus obtained is the same signal as the low speed signal.
- the phase modulation unit 206 reproduces the other optical signal branched by the optical branching unit 201 by the low-speed signal decoding unit 205 with the reverse logic of the low-speed signal phase modulation unit 105.
- Phase modulation is performed according to a low-speed signal.
- the phase shift amount is set to ⁇ / 2 as in the low-speed signal phase modulation unit 105 of the transmission device 100.
- the high-speed optical reception unit 207 performs high-speed optical demodulation by performing demodulation corresponding to the modulation performed by the high-speed signal phase modulation unit 104 on the phase-modulated signal and converts it to an electrical signal. Get the signal. Thereby, the receiving apparatus 200 can separate the high-speed signal and the low-speed signal and acquire each signal.
- the above is the operation of the optical transmission system.
- FIG. 4 is a diagram illustrating a waveform of a signal output from each processing unit according to the first embodiment.
- each period divided by a dotted line extending in the vertical direction corresponds to one symbol bit of the low-speed signal.
- FIG. 4A shows the phase transition of the optical signal output from the high-speed signal phase modulator 104.
- FIG. 4A the vertical axis indicates the phase, and the horizontal axis indicates time.
- the phase of the optical signal output from the high-speed signal phase modulation unit 104 transitions between 0 and ⁇ .
- FIG. 4B shows the phase transition of the optical signal output from the low-speed signal phase modulator 105.
- the vertical axis indicates the phase
- the horizontal axis indicates time.
- the phase of the optical signal output from the low-speed signal phase modulator 105 transitions between 0, ⁇ / 2, ⁇ , and 3 ⁇ / 2. Further, the phase transitions between ⁇ / 2 and 3 ⁇ / 2 during the period when the bit of the low-speed signal is 1, and the phase transitions between 0 and ⁇ during the period when the bit of the low-speed signal is 0.
- FIG. 4C shows the voltage transition of the electric signal output from the light detection unit 203.
- the vertical axis represents voltage
- the horizontal axis represents time.
- the electrical signal output from the light detection unit 203 transitions between V, 0, and ⁇ V.
- the electrical signal output from the light detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal.
- the delay interference unit 202 performs delay interference of the optical signal branched by the optical branching unit 201, that is, the optical signal output from the low-speed signal phase modulation unit 105. At this time, when the phase difference between adjacent symbols is 0, the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201.
- the intensity of the optical signal output from the delay interference unit 202 is zero.
- the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to ⁇ V when the intensity of the input optical signal is 0. Therefore, the output signal of the light detection unit 203 has a voltage of V or ⁇ V according to the phase difference between adjacent symbols of the optical signal output from the low-speed signal phase modulation unit 105, and the symbol bits of the low-speed signal are switched.
- the voltage is zero only at the points.
- FIG. 4D shows the transition of the voltage of the electric signal output from the rectifying unit 204. In FIG. 4D, the vertical axis represents voltage, and the horizontal axis represents time.
- the electrical signal output from the rectifying unit 204 transitions between V and 0.
- the rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Accordingly, the voltage is 0 only at the switching point of the symbol bit of the low-speed signal, and the voltage is V in the other periods.
- the low-speed signal decoding unit 205 changes the pulse level of the output signal at the falling edge of the pulse of the electric signal output from the rectifying unit 204, that is, changes the pulse level of the output signal at a point where the voltage becomes zero.
- a low-speed signal can be extracted from the optical signal branched by the optical branching unit 201.
- the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise.
- the low-speed signal decoding unit 205 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
- the transmission device 100 superimposes the low-speed signal on the optical signal phase-modulated according to the high-speed signal using the phase modulation.
- the receiving apparatus 200 performs delayed interference, converts the interference light into an electrical signal, and acquires a low-speed signal.
- the receiving device 200 reproduces a high-speed signal by phase-modulating and decoding the optical signal acquired from the transmitting device 100 according to the low-speed signal acquired from the optical signal. Thereby, a high speed signal and a low speed signal can be multiplexed.
- the transmission device 100 superimposes a high-speed signal and a low-speed signal using optical signals having the same wavelength.
- the transmission apparatus 100 performs the phase modulation of the high speed signal by the high speed signal phase modulation unit 104 and performs the phase modulation of the low speed signal by the low speed signal phase modulation unit 105. Accordingly, it is possible to easily implement by adding a necessary part to an existing optical transmission system, such as adding a low-speed signal phase modulation unit 105 when necessary. Further, according to the present embodiment, the transmission device 100 performs superimposition of the low-speed signals by phase modulation, so that the intensity of the optical signal output from the high-speed signal phase modulation unit 104 is not lost.
- the low-speed signal portion is removed from the superimposed signal by reproducing the low-speed signal by the receiving apparatus 200, the information on the light intensity is not lost. As a result, it is possible to multiplex a low-speed signal without greatly losing the long-distance transmission characteristic of the optical signal modulated according to the high-speed signal.
- the delay amount of the delay interference unit 202 corresponds to one symbol time of a high-speed signal
- the present invention is not limited to this.
- the delay amount is set to one symbol time of the low-speed signal, the time for the voltage of the electric signal input to the low-speed signal decoding unit 205 to become zero is lengthened, and the identification margin of the low-speed signal decoding unit 205 is widened. The possibility of error may be reduced.
- the high-speed signal phase modulation unit 104 performs phase modulation.
- the present invention is not limited to this, and the high-speed signal phase modulation unit 104 may perform differential phase shift keying.
- a LiNbO 3 Mach-Zehnder modulator or the like is used as the high-speed signal phase modulation unit 104, and a high-speed optical reception unit 207 is combined with, for example, a Mach-Zehnder type delay interferometer, a photodetector circuit, and a phase modulation decoding circuit, By using a receiving circuit or the like based on the coherent light receiving method, the transmitting device 100 and the receiving device 200 can be mounted.
- the second embodiment is an example of an optical transmission system in which a low-speed signal is pre-coded by the transmission device 100 and the low-speed signal is acquired without the reception device 200 decoding the low-speed signal.
- the low-speed signal decoding unit 205 of the receiving apparatus 200 described in the first embodiment changes the level of the output signal in response to the falling edge of the pulse of the input signal. Therefore, if a bit error exists, a signal in which the bits after the erroneous bit are inverted is output. For this reason, when a low-speed signal is decoded in the receiving apparatus 200 in which noise is included in the received optical signal, an error occurs in a burst manner.
- the error rate of the low-speed signal is increased, but also the output result of the phase modulation unit 206 is erroneous, so that the error rate of the high-speed signal is also increased. Therefore, if the low-speed signal can be acquired without performing decoding processing in the receiving apparatus 200, the error rate can be reduced for both the low-speed signal and the high-speed signal.
- FIG. 5 is a schematic block diagram showing the configuration of the optical transmission system according to the second embodiment of the present invention.
- the configuration of the optical transmission system according to the second embodiment includes a precoding unit 111 in addition to the transmission device 100 in addition to the first embodiment, and low-speed signal detection instead of the low-speed signal decoding unit 205 of the reception device 200. It is the structure provided with the part 211.
- the other processing units are the same as those of the optical transmission system according to the first embodiment, and therefore will be described using the same reference numerals.
- the precoding unit 111 and the low-speed signal phase modulation unit 105 correspond to the low-speed signal modulation unit of the present invention.
- the low speed signal detection unit 211 corresponds to the low speed signal acquisition unit of the present invention.
- the phase modulation unit 206 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
- the precoding unit 111 of the transmission device 100 performs low-code signal precoding.
- the precoding unit 111 performs precoding by changing the pulse level of the output signal when the bit of the input electric signal is 1 (when it is at a predetermined level).
- the low-speed signal phase modulation unit 105 performs phase modulation of the optical signal phase-modulated by the high-speed signal phase modulation unit 104 according to the low-speed signal subjected to precoding.
- the low-speed signal detection unit 211 of the reception device 200 detects the electric signal that has been full-wave rectified by the rectification unit 204 without performing decoding processing, and acquires a low-speed signal.
- FIG. 6 is a diagram illustrating a waveform of a signal output from each processing unit according to the second embodiment.
- FIG. 6A shows bit transition of a signal output from the low-speed signal output unit 103.
- the vertical axis indicates a bit value
- the horizontal axis indicates time. The low speed signal transitions between 1 and 0.
- FIG. 6B shows bit transition of a signal output from the precoding unit 111.
- the vertical axis indicates a bit value
- the horizontal axis indicates time.
- the output signal of the precoding unit 111 transitions between 1 and 0.
- the precoding unit 111 inverts the bit value of the output signal when the bit of the low-speed signal becomes 1.
- FIG. 6C shows the phase transition of the optical signal output from the low-speed signal phase modulation unit 105.
- the vertical axis indicates the phase
- the horizontal axis indicates time.
- the phase of the optical signal output from the low-speed signal phase modulator 105 transitions between 0, ⁇ / 2, ⁇ , and 3 ⁇ / 2.
- phase transitions between ⁇ / 2 and 3 ⁇ / 2 during the period when the bit of the output signal of the precoding unit 111 is 1, and the phase is 0 during the period when the bit of the output signal of the precoding unit 111 is 0. Transition to ⁇ .
- FIG. 6D shows the voltage transition of the electrical signal output from the light detection unit 203.
- the vertical axis represents voltage
- the horizontal axis represents time.
- the electrical signal output from the light detection unit 203 transitions between V, 0, and ⁇ V.
- the electrical signal output from the light detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal.
- the delay interference unit 202 performs delay interference of one optical signal branched by the optical branching unit 201, that is, the optical signal output from the low-speed signal phase modulation unit 105. At this time, when the phase difference between adjacent symbols is 0, the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201.
- the intensity of the optical signal output from the delay interference unit 202 is zero.
- the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to ⁇ V when the intensity of the input optical signal is 0. Accordingly, the output signal of the light detection unit 203 has a voltage of 0 when the bit of the low-speed signal becomes 1, and the voltage is V or ⁇ V otherwise.
- FIG. 6E shows the transition of the voltage of the electric signal output from the rectifying unit 204. In FIG. 6E, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifying unit 204 transitions between V and 0. The rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Therefore, the voltage of the electrical signal output from the rectifying unit 204 is 0 when the bit of the low-speed signal becomes 1, and the voltage is V when the bit of the low-speed signal is 0.
- the low-speed signal detection unit 211 outputs 1 when the voltage of the electrical signal output from the rectification unit 204 becomes 0, and outputs 0 when the voltage is V, thereby acquiring a low-speed signal. It can. It should be noted that the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise. As a result, there is a possibility that the low-speed signal detection unit 211 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
- the transmission apparatus 100 pre-codes the low-speed signal, and performs phase modulation of the optical signal phase-modulated according to the high-speed signal in accordance with the pre-coded low-speed signal.
- the receiving apparatus 200 can acquire a low-speed signal without decoding the low-speed signal, and thus can suppress the propagation of errors due to the decoding.
- the delay amount of the delay interference unit 202 corresponds to one symbol time of a high-speed signal
- the present invention is not limited to this.
- the delay amount is set to one symbol time of the low-speed signal, the time during which the voltage of the electric signal input to the low-speed signal detection unit 211 becomes 0 is lengthened, and the identification margin of the low-speed signal detection unit 211 is widened. The possibility of error may be reduced.
- the third embodiment performs phase modulation of an optical signal that is phase-modulated in accordance with a high-speed signal in accordance with a signal that is a logical product of a clock signal obtained by dividing the frequency of the high-speed signal by 2 and a low-speed signal. It is an example of an optical transmission system. As a result, the low-speed signal is acquired without decoding the low-speed signal by the receiving apparatus 200.
- FIG. 7 is a schematic block diagram showing a configuration of an optical transmission system according to the third embodiment of the present invention.
- the configuration of the optical transmission system according to the third embodiment includes a clock output unit 121 and an AND operation unit 122 in addition to the transmission device 100 in addition to the first embodiment, and a low-speed signal decoding unit of the reception device 200. Instead of 205, a low-speed signal detection unit 211 is provided.
- the other processing units are the same as those of the optical transmission system according to the first embodiment, and therefore will be described using the same reference numerals.
- the clock output unit 121, the AND operation unit 122, and the low-speed signal phase modulation unit 105 correspond to the low-speed signal modulation unit of the present invention.
- the low speed signal detection unit 211 corresponds to the low speed signal acquisition unit of the present invention.
- the phase modulation unit 206 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
- the clock output unit 121 of the transmission apparatus 100 outputs a clock signal having a frequency obtained by dividing the frequency of the high-speed signal by two (that is, a clock signal whose frequency is half the symbol rate of the high-speed signal).
- the logical product operation unit 122 outputs a logical product of the low-speed signal output from the low-speed signal output unit 103 and the clock signal output from the clock output unit 121.
- the optical phase amplitude is switched by ⁇ / 2 with one symbol time of the high-speed signal as a cycle.
- the AND operation unit 122 for example, an AND circuit is used.
- the low-speed signal phase modulation unit 105 performs phase modulation of the optical signal phase-modulated by the high-speed signal phase modulation unit 104 in accordance with the signal output from the AND operation unit 122.
- the low-speed signal detection unit 211 of the reception device 200 detects the electric signal that has been full-wave rectified by the rectification unit 204 without performing decoding processing, and acquires a low-speed signal.
- FIG. 8 is a diagram illustrating a waveform of a signal output from each processing unit according to the third embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
- FIG. 8A shows the phase transition of the optical signal output from the high-speed signal phase modulation unit 104. In FIG. 8A, the vertical axis indicates the phase, and the horizontal axis indicates time.
- FIG. 8B shows the phase transition of the optical signal output from the low-speed signal phase modulator 105.
- the vertical axis indicates the phase
- the horizontal axis indicates time.
- the phase of the optical signal output from the low-speed signal phase modulator 105 transitions between 0, ⁇ / 2, ⁇ , and 3 ⁇ / 2. At this time, the phase is 0 or ⁇ during the period when the bit of the low-speed signal is 0.
- FIG. 8C shows the transition of the voltage of the electric signal output from the light detection unit 203.
- the vertical axis represents voltage
- the horizontal axis represents time.
- the electrical signal output from the light detection unit 203 transitions between V, 0, and ⁇ V.
- the electrical signal output from the light detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal.
- the delay interference unit 202 performs delay interference of one optical signal branched by the optical branching unit 201, that is, the optical signal output from the low-speed signal phase modulation unit 105.
- the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201.
- the phase difference between adjacent symbols is ⁇
- the intensity of the optical signal output from the delay interference unit 202 is zero.
- the phase difference between adjacent symbols is ⁇ / 2 or 3 ⁇ / 2
- the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to ⁇ V when the intensity of the input optical signal is 0. Therefore, the output signal of the light detection unit 203 has a voltage of V or ⁇ V according to the phase difference between adjacent symbols of the optical signal output from the low-speed signal phase modulation unit 105. When the bit of the low speed signal is 1, the voltage is 0.
- FIG. 8D shows the transition of the voltage of the electric signal output from the rectifying unit 204.
- the vertical axis represents voltage
- the horizontal axis represents time. The electrical signal output from the rectifying unit 204 transitions between V and 0.
- the rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Therefore, the voltage is 0 when the bit of the low-speed signal is 1, and the voltage is V when the bit of the low-speed signal is 0.
- the low-speed signal detector 211 can acquire a low-speed signal by outputting 1 when the voltage of the electrical signal output from the rectifier 204 is 0 and outputting 0 when the voltage is V. It should be noted that the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise. As a result, there is a possibility that the low-speed signal detection unit 211 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
- the receiving apparatus 200 in accordance with the signal that is the logical product of the clock signal obtained by dividing the frequency of the high-speed signal by 2 and the low-speed signal in the transmission apparatus 100, Perform phase modulation. As a result, the receiving apparatus 200 can acquire a low-speed signal without decoding the low-speed signal, and thus can suppress the propagation of errors due to the decoding.
- the transmitter 100 performs frequency modulation of an optical signal phase-modulated according to a high-speed signal in response to a low-speed signal, and the receiver 200 acquires the low-speed signal without decoding the low-speed signal. It is an example of a transmission system.
- FIG. 9 is a schematic block diagram showing a configuration of an optical transmission system according to the fourth embodiment of the present invention.
- the configuration of the optical transmission system according to the fourth embodiment includes a frequency modulation unit 131 instead of the low-speed signal phase modulation unit 105 of the transmission device 100 of the first embodiment, and the low-speed signal decoding unit 205 of the reception device 200.
- a low-speed signal detection unit 211 is provided instead of the frequency modulation unit 231, and a frequency modulation unit 231 is provided instead of the phase modulation unit 206 of the reception device 200.
- the other processing units are the same as those of the optical transmission system according to the first embodiment, and therefore will be described using the same reference numerals.
- the frequency modulation unit 131 corresponds to the low-speed signal modulation unit of the present invention.
- the low speed signal detection unit 211 corresponds to the low speed signal acquisition unit of the present invention.
- the frequency modulation unit 231 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
- the low-speed signal detection unit 211 of the reception device 200 detects the electric signal that has been full-wave rectified by the rectification unit 204 without performing a decoding process, and acquires a low-speed signal.
- the frequency modulation unit 231 of the reception device 200 performs frequency modulation of the other optical signal branched by the optical branching unit 201 in accordance with the signal output from the low-speed signal detection unit 211. Similarly to the frequency modulation unit 131, the frequency modulation unit 231 uses a frequency corresponding to 1 ⁇ 4 of the reciprocal of the delay amount of the delay interference unit 202 as the frequency shift amount.
- FIG. 10 is a diagram illustrating a waveform of a signal output from each processing unit according to the fourth embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
- FIG. 10A shows bit transition of the signal output from the low-speed signal output unit 103.
- FIG. 10A shows the vertical axis and the horizontal axis represents time.
- the signal output from the low-speed signal output unit 103 transitions between 0 and 1.
- FIG. 10B shows the phase transition of the optical signal output from the frequency modulation unit 131.
- the vertical axis indicates the phase
- the horizontal axis indicates time.
- the phase of the optical signal output from the frequency modulation unit 131 is 0 or ⁇ during the period when the bit of the low-speed signal is 0, and the phase continues to shift by ⁇ / 2 per 25 ps during the period when the bit of the low-speed signal is 1. . This is because the phase is rotated by ⁇ / 2 at 25 ps because frequency modulation is performed with a frequency shift amount of 10 Gbps.
- FIG. 10C shows the transition of the voltage of the electric signal output from the light detection unit 203.
- the vertical axis represents voltage
- the horizontal axis represents time.
- the electrical signal output from the light detection unit 203 transitions between V, 0, and ⁇ V.
- the voltage is 0, and when the bit of the low-speed signal is 0, the voltage is V or -V.
- the voltage smoothly transitions from 0 to V or ⁇ V, or from V or ⁇ V to 0.
- the electrical signal output from the light detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal.
- the delay interference unit 202 performs delay interference of the optical signal branched by the optical branching unit 201, that is, the optical signal output from the frequency modulation unit 131. At this time, when the phase difference between adjacent symbols is 0, the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201. When the phase difference between adjacent symbols is ⁇ , the intensity of the optical signal output from the delay interference unit 202 is zero. When the phase difference between adjacent symbols is ⁇ / 2 or 3 ⁇ / 2, the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201.
- the light detection unit 203 sets the voltage of the output signal to ⁇ V when the intensity of the input optical signal is 0. Therefore, the voltage output from the delay interference unit 202 is V or ⁇ V depending on the phase difference between adjacent symbols of the optical signal output from the frequency modulation unit 131, and the bit of the low-speed signal is 1. In this case, the voltage becomes zero.
- FIG. 10D shows the transition of the voltage of the electric signal output from the rectifying unit 204.
- the vertical axis represents voltage
- the horizontal axis represents time.
- the electrical signal output from the rectifying unit 204 transitions between V and 0.
- the rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Therefore, the voltage is 0 when the bit of the low-speed signal is 1, and the voltage is V when the bit of the low-speed signal is 0.
- the low-speed signal detection unit 211 can obtain a low-speed signal by outputting 1 when the voltage of the electrical signal output from the rectification unit 204 is 0 and outputting 0 when the voltage is V.
- the electrical signal output from the rectifying unit 204 has a smooth rise and fall of the voltage
- the low-speed signal detection unit 211 needs to detect at a timing when the rise or fall of the voltage is stable.
- the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise.
- the low-speed signal detection unit 211 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
- the transmission apparatus 100 performs frequency modulation of the optical signal phase-modulated according to the high-speed signal according to the low-speed signal.
- the receiving apparatus 200 can acquire a low-speed signal without decoding the low-speed signal, and thus can suppress the propagation of errors due to the decoding.
- the delay amount of the delay interference unit 202 corresponds to one symbol time of a high-speed signal has been described, but the present invention is not limited to this.
- the spectral spread of the optical signal transmitted from the transmission unit 106 may be reduced by setting the delay amount to one symbol time of the low-speed signal and the frequency shift amount of the frequency modulation unit 131 to 2.5 GHz.
- the receiving apparatus 200 includes the frequency modulation unit 231 and removes the low-speed signal component to extract the high-speed signal.
- the present invention is not limited to this.
- the frequency modulation unit 231 is provided.
- the structure of the receiving apparatus 200 may be simplified by directly decoding the optical signal branched by the optical branching unit 201 by the high-speed optical receiving unit 207.
- FIG. 11 is a schematic block diagram showing the configuration of the rectifying unit according to the fifth embodiment.
- the rectification unit 204 includes a light source unit 241, a Mach-Zehnder modulation unit 242, and a light detection unit 243.
- the light source unit 241 outputs CW light.
- the Mach-Zehnder modulation unit 242 modulates the intensity of the CW light based on the electric signal output from the light detection unit 203.
- the Mach-Zehnder modulation unit 242 previously adjusts the bias voltage so that the intensity of the optical signal output when the voltage of the electrical signal output by the light detection unit 203 is 0 is 0.
- the intensity of the optical signal output from the Mach-Zehnder modulation unit 242 becomes 0, and the voltage of the electrical signal output from the light detection unit 203 is V or ⁇ At V, the intensity of the optical signal output from the Mach-Zehnder modulator 242 is maximized.
- the light detection unit 243 converts the optical signal output from the Mach-Zehnder modulation unit 242 into an electrical signal. The light detection unit 243 sets the voltage of the electrical signal output when the intensity of the optical signal is 0 to 0, and sets the voltage of the electrical signal output when the intensity of the optical signal is maximum to V.
- the rectifying unit 204 can output an electrical signal equivalent to the full-wave rectifying circuit.
- the rectifying unit 204 according to the present embodiment does not use an integrated circuit such as an operational amplifier, and the Mach-Zehnder modulating unit 242 can easily operate at high speed, and thus can obtain a full-wave rectified waveform with less distortion. Can do.
- a multiplexed signal of a first signal and a second signal that is slower than the first signal can be made a unimodal spectrum, and a plurality of signals can be placed in a single wavelength slot. Can fit in.
- DESCRIPTION OF SYMBOLS 100 ... Transmission apparatus 101 ... Light source part 102 ... High speed signal output part 103 ... Low speed signal output part 104 ... High speed signal phase modulation part 105 ... Low speed signal phase modulation part 106 ... Transmission part 200 ... Reception apparatus 201 ... Optical branching part 202 ... Delay Interference unit 203 ... optical detection unit 204 ... rectification unit 205 ... low-speed signal decoding unit 206 ... phase modulation unit 207 ... high-speed optical reception unit
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Abstract
Provided are an optical transmission system and an optical transmission method which can be implemented by multiplexing a plurality of signals with different speed, multiplexing information to a single wavelength slot in the form of a single-peaked spectrum, and adding a portion required for an existing system. A transmitter performs phase modulation with the amount of a phase shift π to output an optical signal which has been phase-modulated according to a first signal, and transmits to a receiver an optical signal which has been obtained by phase-modulating or frequency-modulating the phase-modulated optical signal based on a second signal slower than the first signal. The receiver obtains the optical signal from the transmitter to branch the obtained signal, performs the delay interference of one of the branched optical signals to output the interfered light, converts the interfered light into an electrical signal to subject the converted signal to full-wave rectification, obtains the second signal based on the electrical signal which has been subjected to the full-wave rectification, and obtains the first signal based on the other of the branched optical signals.
Description
本発明は、複数の信号を1波長の光に多重する方法に関し、特に高速位相変調信号に低速信号を重畳して伝送する送信装置、受信装置、光伝送システム及び光伝送方法に関する。
The present invention relates to a method of multiplexing a plurality of signals on one wavelength of light, and more particularly to a transmission device, a reception device, an optical transmission system, and an optical transmission method for transmitting a low-speed signal superimposed on a high-speed phase modulation signal.
光ファイバ通信システムは、長距離大容量の通信を実現する重要な技術となっている。大容量の通信は、送受信に用いられる変復調用のデバイス、および伝送路となる光ファイバの広帯域な特性を用いて実現されている。この特性を生かして、近年では、100Gbps(ギガビット毎秒)のインターフェース容量を有する光伝送システムの実現が可能な技術が多数実現している。
光ファイバ通信システムを用いて、低速の信号を集約して、1システムにて大容量化伝送を実現する手段としては、これまで、時分割多重方式、および波長分割多重方式が用いられてきた。 The optical fiber communication system has become an important technology for realizing long-distance and large-capacity communication. Large-capacity communication is realized using modulation / demodulation devices used for transmission and reception, and the broadband characteristics of optical fibers serving as transmission paths. Taking advantage of this characteristic, in recent years, many technologies capable of realizing an optical transmission system having an interface capacity of 100 Gbps (gigabits per second) have been realized.
Up to now, time division multiplexing systems and wavelength division multiplexing systems have been used as means for aggregating low-speed signals using an optical fiber communication system and realizing large capacity transmission in one system.
光ファイバ通信システムを用いて、低速の信号を集約して、1システムにて大容量化伝送を実現する手段としては、これまで、時分割多重方式、および波長分割多重方式が用いられてきた。 The optical fiber communication system has become an important technology for realizing long-distance and large-capacity communication. Large-capacity communication is realized using modulation / demodulation devices used for transmission and reception, and the broadband characteristics of optical fibers serving as transmission paths. Taking advantage of this characteristic, in recent years, many technologies capable of realizing an optical transmission system having an interface capacity of 100 Gbps (gigabits per second) have been realized.
Up to now, time division multiplexing systems and wavelength division multiplexing systems have been used as means for aggregating low-speed signals using an optical fiber communication system and realizing large capacity transmission in one system.
時分割多重方式を用いた光伝送システムにおいて、送信装置は、周波数同期した低速信号群を電気的に多重して高速電気信号を生成して、この高速電気信号を用いて光を変調して伝送する方式を採用している。また受信装置は、変調した光を検波、識別再生し、時分割方向に分離することにより、多重信号を分離して元の低速信号群を再生する。この方式は、電気的な多重を利用して高速信号を生成できること、またシステムのコストの多くを占める光デバイスが送受信1組でよいことなどから、多重を利用してシステムコストの上昇を抑えることが可能であるというメリットを有する。
In an optical transmission system using time division multiplexing, a transmitter generates a high-speed electrical signal by electrically multiplexing a group of low-speed signals synchronized in frequency, and modulates and transmits light using the high-speed electrical signal. The method to do is adopted. Further, the receiving apparatus detects the modulated light, discriminates and reproduces it, and separates it in the time division direction, thereby separating the multiplexed signal and reproducing the original low-speed signal group. In this method, high-speed signals can be generated using electrical multiplexing, and optical devices that occupy most of the system cost can be one set of transmission and reception. Has the advantage of being possible.
一方、波長分割多重方式を用いた光伝送システムにおいて、送信装置は、互いに異なる信号波長で発振する光源を有する複数の光送信部を用い、これらの光送信部が出力する光を複数の電気信号で変調する。次に、送信装置は、複数の変調された光を、波長多重回路を用いて多重して、1ファイバ上を伝送させる。また受信装置では、光分離回路を用いて複数の波長を個別に分離した後、複数の受信部を用いて信号を検波、識別再生する。この方式では、低速の信号が異なる方式、フォーマットであっても、多重が可能である。また、この方式では、非常に広い光ファイバの伝送帯域を利用して、非常に多数の波長チャネルを多重することができ、大容量化を容易に実現することが可能である。こうしたことから、この方式は、前述の時分割多重方式と組み合わせて、広く実用化が進んでいる。
On the other hand, in an optical transmission system using a wavelength division multiplexing system, a transmission device uses a plurality of optical transmission units having light sources that oscillate at different signal wavelengths, and outputs light output from these optical transmission units to a plurality of electrical signals. Modulate with. Next, the transmission apparatus multiplexes a plurality of modulated lights using a wavelength multiplexing circuit and transmits the multiplexed light on one fiber. In the receiving apparatus, a plurality of wavelengths are individually separated using an optical separation circuit, and then a signal is detected and identified and reproduced using a plurality of receiving units. In this method, multiplexing is possible even if the low-speed signal has a different method and format. In this system, a very large number of wavelength channels can be multiplexed using a very wide transmission band of an optical fiber, and a large capacity can be easily realized. For this reason, this method has been widely put into practical use in combination with the aforementioned time division multiplexing method.
ところで、高速な光通信の長距離伝送を実現する上で、大きく2つの課題がある。1つめは、光雑音蓄積に対する対策である。強度変調方式において、伝送速度を高速化すると、使用する信号帯域が増加するため、システムが受ける雑音の量も増大する。この結果、受信装置における信号対雑音比の値が小さくなるため、符号誤りが増加するという品質劣化が生じる。2つめは、伝送距離を長距離化すると、損失補償のための光増幅中継器を増やす必要があり、この光増幅中継器が発生する光雑音の蓄積に起因して、受信装置における信号対雑音比の劣化が生じる。したがって、高速化、長距離化を実現するためには、光雑音蓄積の低減、もしくは光雑音蓄積に強い伝送方式の開発が必要となる。
By the way, there are two major problems in realizing long-distance transmission of high-speed optical communication. The first is a measure against optical noise accumulation. In the intensity modulation method, when the transmission speed is increased, the signal band to be used increases, and the amount of noise received by the system also increases. As a result, the value of the signal-to-noise ratio in the receiving apparatus becomes small, resulting in a quality deterioration in which code errors increase. Secondly, if the transmission distance is increased, it is necessary to increase the number of optical amplification repeaters for loss compensation. Due to the accumulation of optical noise generated by this optical amplification repeater, the signal-to-noise in the receiving apparatus is increased. Ratio degradation occurs. Therefore, in order to realize high speed and long distance, it is necessary to reduce the accumulation of optical noise or develop a transmission system that is strong against optical noise accumulation.
近年、このような光雑音蓄積の課題に対して、位相変調方式、特に差動位相偏移変調(DPSK:Differential Phase Shift Keying)方式が注目されている(例えば特許文献1)。差動位相偏移変調方式は、デジタル信号の1、0を伝送するために、隣り合うビットスロットの光の位相をπだけ変化させるという方式である。特に、位相変調方式に1ビット遅延検波受信方式を組み合わせたシステムは、性能の高さと構成の簡易さという利点で注目されている。このシステムでは、送信装置は、送信データが1の場合は、ビットスロットの位相をπだけ変化させ、送信データが0の時には光位相をそのままとする。受信装置は、一方に1ビット遅延素子を配置した2つの分岐に受信信号を分配した後、2つの信号を干渉させる。この結果、現ビットスロットの信号と1ビットスロット前の信号との位相差が2πまたは0になると干渉信号の強度が最大になり、位相差がπとなると消光する。この原理を利用して、受信装置は、位相変化に印加された情報を強度情報に変換して受信する。
In recent years, a phase modulation method, particularly a differential phase shift keying (DPSK) method has attracted attention for such a problem of optical noise accumulation (for example, Patent Document 1). The differential phase shift keying method is a method in which the phase of light in adjacent bit slots is changed by π in order to transmit digital signals 1 and 0. In particular, a system in which a 1-bit delay detection reception system is combined with a phase modulation system has attracted attention due to the advantages of high performance and simple configuration. In this system, when the transmission data is 1, the transmission apparatus changes the phase of the bit slot by π, and when the transmission data is 0, the optical phase remains unchanged. The receiving apparatus distributes the received signal to two branches having one-bit delay elements arranged on one side, and then causes the two signals to interfere with each other. As a result, when the phase difference between the signal of the current bit slot and the signal of the previous bit slot becomes 2π or 0, the intensity of the interference signal becomes maximum, and when the phase difference becomes π, the signal is extinguished. Using this principle, the receiving apparatus converts the information applied to the phase change into intensity information and receives it.
今後、さらに大容量なサービスの伝送を実現する上では、いくつかの要求条件がある。例えば、次に述べる要求条件が挙げられる。第1に、複数の非常に高速な電気信号を柔軟に多重できること、たとえば非同期な信号であっても多重できることである。第2に、サービスの管理を容易にするため、可能な限り単一の波長スロット内に複数の信号を収容することである。第3に、サービスの需要が発生したときに柔軟に対応する必要があり、高速化が必要となったときに必要部位を追加して実装できる設計となっていることである。
In the future, there are several requirements for realizing transmission of larger-capacity services. For example, the following requirements are mentioned. First, a plurality of very high-speed electrical signals can be flexibly multiplexed, for example, even asynchronous signals can be multiplexed. Second, to facilitate service management, the multiple signals are accommodated in a single wavelength slot as much as possible. Thirdly, it is necessary to respond flexibly when demand for services occurs, and when it is necessary to increase the speed, it is designed so that necessary parts can be added and mounted.
このような要求条件を鑑みて大容量化を進める上で、これまでの技術ではいくつかの課題がある。具体的には、時分割多重方式を用いる場合、電気信号の多重を行い、当該電気信号で光の変調を行わなければならないが、非常に高速な電気信号の処理を行うことが困難であるという問題がある。また、多重電気回路を変更しなければならないため、既存の光伝送システムに必要部位を追加する設計を実現することは非常に困難である。
In view of these requirements, there are several problems with the conventional technology in increasing the capacity. Specifically, when the time division multiplexing method is used, it is necessary to multiplex electric signals and modulate light with the electric signals, but it is difficult to process very high-speed electric signals. There's a problem. In addition, since it is necessary to change the multiple electric circuit, it is very difficult to realize a design in which a necessary part is added to an existing optical transmission system.
一方、波長分割多重方式を用いる場合は、単一の波長スロットに複数の信号を収容することが、一般的には困難であることが課題である。特に、波長スロットの帯域幅だけならば、複数のピークを高密度に多重することで、1つの波長スロット内に波長多重を行うことも可能であるが、このようなピークが複数ある信号の監視は困難であることから、できるだけ単峰的なスペクトルとなっていることが好ましい。
さらに、位相変調方式を用いる場合は、これまでの方法では複数の電気信号を多重することができなかった。 On the other hand, when wavelength division multiplexing is used, it is generally difficult to accommodate a plurality of signals in a single wavelength slot. In particular, if only the bandwidth of the wavelength slot is used, it is possible to perform wavelength multiplexing within one wavelength slot by multiplexing a plurality of peaks with high density, but monitoring a signal having a plurality of such peaks. Therefore, it is preferable that the spectrum is as unimodal as possible.
Further, when the phase modulation method is used, a plurality of electric signals cannot be multiplexed by the conventional methods.
さらに、位相変調方式を用いる場合は、これまでの方法では複数の電気信号を多重することができなかった。 On the other hand, when wavelength division multiplexing is used, it is generally difficult to accommodate a plurality of signals in a single wavelength slot. In particular, if only the bandwidth of the wavelength slot is used, it is possible to perform wavelength multiplexing within one wavelength slot by multiplexing a plurality of peaks with high density, but monitoring a signal having a plurality of such peaks. Therefore, it is preferable that the spectrum is as unimodal as possible.
Further, when the phase modulation method is used, a plurality of electric signals cannot be multiplexed by the conventional methods.
本発明は上記の課題を解決するためになされたものであり、その目的は、速度の異なる複数の信号を多重し、単一波長スロットに単峰的なスペクトル形状で情報を多重し、既存のシステムに必要部位を追加することで実装できる送信装置、受信装置、光伝送システム及び光伝送方法を提供することにある。
The present invention has been made in order to solve the above-described problems. The purpose of the present invention is to multiplex a plurality of signals having different speeds, multiplex information with a single peak spectral shape in a single wavelength slot, and An object of the present invention is to provide a transmission device, a reception device, an optical transmission system, and an optical transmission method that can be implemented by adding necessary parts to the system.
本発明は上記の課題を解決するためになされたものであり、本発明の送信装置は、速度が異なる2つの信号を1つの光信号に多重して送信する送信装置であって、第1の信号を出力する高速信号出力部と、前記第1の信号に応じて、位相シフト量をπとした位相変調を行う高速信号位相変調部と、前記第1の信号よりも低速な第2の信号を出力する低速信号出力部と、前記第2の信号に基づいて、前記高速信号位相変調部が出力した光信号の位相変調または周波数変調を行う低速信号変調部と、前記低速信号変調部が出力した光信号を受信装置に送信する送信部とを備えている。
The present invention has been made in order to solve the above-described problem, and a transmission apparatus according to the present invention is a transmission apparatus that multiplexes two signals having different speeds into one optical signal and transmits the multiplexed signal. A high-speed signal output unit that outputs a signal, a high-speed signal phase modulation unit that performs phase modulation with a phase shift amount π in accordance with the first signal, and a second signal that is slower than the first signal A low-speed signal output unit that outputs a signal, a low-speed signal modulation unit that performs phase modulation or frequency modulation of an optical signal output from the high-speed signal phase modulation unit based on the second signal, and an output from the low-speed signal modulation unit And a transmitter that transmits the optical signal thus received to the receiver.
また、本発明の受信装置は、速度が異なる2つの信号を多重した1つの光信号を受信する受信装置であって、第1の信号に応じて位相シフト量をπとした位相変調を行ってから前記第1の信号よりも低速な第2の信号に基づいて位相変調または周波数変調した光信号を送信装置から取得して分岐する光分岐部と、前記分岐した一方の光信号の遅延干渉を行い、干渉光を出力する遅延干渉部と、前記干渉光を電気信号に変換する光検出部と、前記電気信号を全波整流する整流部と、前記全波整流した電気信号に基づいて前記第2の信号を取得する低速信号取得部と、前記分岐した他方の光信号に基づいて前記第1の信号を取得する高速信号取得部とを備えている。
また、本発明の光伝送システムは、本発明の送信装置および本発明の受信装置を備えている。 The receiving apparatus of the present invention is a receiving apparatus that receives one optical signal obtained by multiplexing two signals having different speeds, and performs phase modulation with a phase shift amount π according to the first signal. From an optical branching unit for branching an optical signal that has been phase-modulated or frequency-modulated based on a second signal that is slower than the first signal from a transmitter, and delay interference of the one branched optical signal A delay interference unit that outputs interference light, a light detection unit that converts the interference light into an electrical signal, a rectification unit that full-wave rectifies the electrical signal, and the first signal based on the full-wave rectified electrical signal. A low-speed signal acquisition unit that acquires the second signal and a high-speed signal acquisition unit that acquires the first signal based on the other branched optical signal.
The optical transmission system of the present invention includes the transmitting apparatus of the present invention and the receiving apparatus of the present invention.
また、本発明の光伝送システムは、本発明の送信装置および本発明の受信装置を備えている。 The receiving apparatus of the present invention is a receiving apparatus that receives one optical signal obtained by multiplexing two signals having different speeds, and performs phase modulation with a phase shift amount π according to the first signal. From an optical branching unit for branching an optical signal that has been phase-modulated or frequency-modulated based on a second signal that is slower than the first signal from a transmitter, and delay interference of the one branched optical signal A delay interference unit that outputs interference light, a light detection unit that converts the interference light into an electrical signal, a rectification unit that full-wave rectifies the electrical signal, and the first signal based on the full-wave rectified electrical signal. A low-speed signal acquisition unit that acquires the second signal and a high-speed signal acquisition unit that acquires the first signal based on the other branched optical signal.
The optical transmission system of the present invention includes the transmitting apparatus of the present invention and the receiving apparatus of the present invention.
また、本発明の光伝送方法は、速度が異なる2つの信号を1つの光信号に多重して送信する光伝送方法であって、第1の信号を出力し、前記第1の信号に応じて、位相シフト量をπとした位相変調を行って位相変調された光信号を出力し、前記第1の信号よりも低速な第2の信号を出力し、前記第2の信号に基づいて、前記位相変調された光信号の位相変調または周波数変調を行って受信装置に送信する。
The optical transmission method of the present invention is an optical transmission method in which two signals having different speeds are multiplexed and transmitted in one optical signal, and the first signal is output in accordance with the first signal. , Output a phase-modulated optical signal by performing phase modulation with a phase shift amount of π, output a second signal slower than the first signal, and based on the second signal, Phase modulation or frequency modulation of the phase-modulated optical signal is performed and transmitted to the receiver.
また、本発明の光伝送方法は、速度が異なる2つの信号を多重した1つの光信号を受信する光伝送方法であって、第1の信号に応じて位相シフト量をπとした位相変調を行ってから前記第1の信号よりも低速な第2の信号に基づいて位相変調または周波数変調した光信号を送信装置から取得して分岐し、前記分岐した一方の光信号の遅延干渉を行い、干渉光を出力し、前記干渉光を電気信号に変換し、前記電気信号を全波整流し、前記全波整流した電気信号に基づいて前記第2の信号を取得し、前記分岐した他方の光信号に基づいて前記第1の信号を取得する。
The optical transmission method of the present invention is an optical transmission method for receiving one optical signal obtained by multiplexing two signals having different speeds, and performs phase modulation with a phase shift amount π according to the first signal. An optical signal that has been phase-modulated or frequency-modulated based on a second signal that is slower than the first signal and then branched from the transmitter, and performs delayed interference of the one of the branched optical signals, Outputting interference light, converting the interference light into an electrical signal, full-wave rectifying the electrical signal, obtaining the second signal based on the full-wave rectified electrical signal, and branching the other light The first signal is obtained based on the signal.
本発明によれば、送信装置は、第1の信号に応じて位相変調した光信号に第1の信号よりも低速な第2の信号を位相変調または周波数変調を用いて重畳する。受信装置は、送信装置からの光信号に対して遅延干渉を行い、干渉光を電気信号に変換して全波整流した電気信号に基づいて第2の信号を取得する。また、受信装置は、送信装置からの光信号に基づいて(例えば、送信装置からの光信号を受信することで、あるいは、取得した第2の信号に応じて送信装置からの光信号を位相変調または周波数変調してから受信することで)第1の信号を再現する。これにより、第1の信号、第2の信号を多重することができる。
また本発明によれば、送信装置は、同一の波長の光信号を用いて第1の信号と第2の信号とを重畳する。これにより、多重信号が単峰性のスペクトルとなり、複数の信号を単一の波長スロット内に収めることができる。
また本発明によれば、送信装置は、第1の信号に応じた位相変調を高速信号位相変調部で行い、第2の信号に基づいた位相変調または周波数変調を低速信号変調部で行う。これにより、必要なときに低速信号変調部を追加するなど、既存の光伝送システムに必要部位を追加することで簡単に実装することができる。
また本発明によれば、送信装置は、第2の信号の重畳を位相変調もしくは周波数変調で行うため、第1の信号に応じた位相変調信号の強度を失わない。また、受信装置で第2の信号を再現して重畳された信号から第2の信号を除去するため、光強度の情報を失わない。これにより、第1の信号に応じた位相変調信号の長距離伝送特性を大きく失うことなく第2の信号を多重することができる。 According to the present invention, the transmitting apparatus superimposes the second signal, which is slower than the first signal, on the optical signal phase-modulated according to the first signal by using phase modulation or frequency modulation. The receiving apparatus performs delayed interference on the optical signal from the transmitting apparatus, converts the interference light into an electrical signal, and acquires the second signal based on the electrical signal that has been full-wave rectified. Further, the receiving device performs phase modulation on the optical signal from the transmitting device based on the optical signal from the transmitting device (for example, by receiving the optical signal from the transmitting device or according to the acquired second signal). Alternatively, the first signal is reproduced (by receiving after frequency modulation). Thereby, the first signal and the second signal can be multiplexed.
According to the invention, the transmitting apparatus superimposes the first signal and the second signal using optical signals having the same wavelength. As a result, the multiplexed signal becomes a unimodal spectrum, and a plurality of signals can be stored in a single wavelength slot.
According to the present invention, the transmission device performs phase modulation according to the first signal by the high-speed signal phase modulation unit, and performs phase modulation or frequency modulation based on the second signal by the low-speed signal modulation unit. Accordingly, it is possible to easily implement by adding a necessary part to an existing optical transmission system, such as adding a low-speed signal modulation unit when necessary.
In addition, according to the present invention, since the transmission apparatus performs superimposition of the second signal by phase modulation or frequency modulation, the intensity of the phase modulation signal corresponding to the first signal is not lost. In addition, since the second signal is removed from the superimposed signal by reproducing the second signal by the receiving device, information on the light intensity is not lost. As a result, the second signal can be multiplexed without greatly losing the long-distance transmission characteristic of the phase-modulated signal corresponding to the first signal.
また本発明によれば、送信装置は、同一の波長の光信号を用いて第1の信号と第2の信号とを重畳する。これにより、多重信号が単峰性のスペクトルとなり、複数の信号を単一の波長スロット内に収めることができる。
また本発明によれば、送信装置は、第1の信号に応じた位相変調を高速信号位相変調部で行い、第2の信号に基づいた位相変調または周波数変調を低速信号変調部で行う。これにより、必要なときに低速信号変調部を追加するなど、既存の光伝送システムに必要部位を追加することで簡単に実装することができる。
また本発明によれば、送信装置は、第2の信号の重畳を位相変調もしくは周波数変調で行うため、第1の信号に応じた位相変調信号の強度を失わない。また、受信装置で第2の信号を再現して重畳された信号から第2の信号を除去するため、光強度の情報を失わない。これにより、第1の信号に応じた位相変調信号の長距離伝送特性を大きく失うことなく第2の信号を多重することができる。 According to the present invention, the transmitting apparatus superimposes the second signal, which is slower than the first signal, on the optical signal phase-modulated according to the first signal by using phase modulation or frequency modulation. The receiving apparatus performs delayed interference on the optical signal from the transmitting apparatus, converts the interference light into an electrical signal, and acquires the second signal based on the electrical signal that has been full-wave rectified. Further, the receiving device performs phase modulation on the optical signal from the transmitting device based on the optical signal from the transmitting device (for example, by receiving the optical signal from the transmitting device or according to the acquired second signal). Alternatively, the first signal is reproduced (by receiving after frequency modulation). Thereby, the first signal and the second signal can be multiplexed.
According to the invention, the transmitting apparatus superimposes the first signal and the second signal using optical signals having the same wavelength. As a result, the multiplexed signal becomes a unimodal spectrum, and a plurality of signals can be stored in a single wavelength slot.
According to the present invention, the transmission device performs phase modulation according to the first signal by the high-speed signal phase modulation unit, and performs phase modulation or frequency modulation based on the second signal by the low-speed signal modulation unit. Accordingly, it is possible to easily implement by adding a necessary part to an existing optical transmission system, such as adding a low-speed signal modulation unit when necessary.
In addition, according to the present invention, since the transmission apparatus performs superimposition of the second signal by phase modulation or frequency modulation, the intensity of the phase modulation signal corresponding to the first signal is not lost. In addition, since the second signal is removed from the superimposed signal by reproducing the second signal by the receiving device, information on the light intensity is not lost. As a result, the second signal can be multiplexed without greatly losing the long-distance transmission characteristic of the phase-modulated signal corresponding to the first signal.
以下、図面を参照しながら本発明の各実施形態について詳しく説明する。
(第1の実施形態)
まず、本発明の第1の実施形態について説明する。
図1は、本発明の第1の実施形態に従った光伝送システムの構成を示す概略ブロック図である。
光伝送システムは、送信装置100と受信装置200とを備える。
送信装置100は、光源部101と、高速信号出力部102と、低速信号出力部103と、高速信号位相変調部104と、低速信号位相変調部105と、送信部106とを備える。なお、低速信号位相変調部105は本発明の低速信号変調部に相当する。
光源部101は、CW(Continuous Wave:無変調連続波)光を発出する。光源部101には、例えばDFB(Distributed Feedback:分布帰還)レーザ等を用いる。
高速信号出力部102は、所定の周波数のデジタル信号(第1の信号:以下、高速信号とする)を出力する。高速信号出力部102は、例えば40Gbpsの信号を出力する。
低速信号出力部103は、高速信号より低い周波数のデジタル信号(第2の信号:以下、低速信号とする)を出力する。低速信号出力部103は、例えば10Gbpsの信号を出力する。
高速信号位相変調部104は、高速信号に応じてCW光の位相変調を行う。
低速信号位相変調部105は、低速信号に応じて、高速信号位相変調部104が位相変調した光信号の位相変調を行う。
送信部106は、高速信号位相変調部104および低速信号位相変調部105でそれぞれ位相変調を行った光信号を受信装置200に送信する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, a first embodiment of the present invention will be described.
FIG. 1 is a schematic block diagram showing a configuration of an optical transmission system according to the first embodiment of the present invention.
The optical transmission system includes atransmission device 100 and a reception device 200.
Thetransmission device 100 includes a light source unit 101, a high-speed signal output unit 102, a low-speed signal output unit 103, a high-speed signal phase modulation unit 104, a low-speed signal phase modulation unit 105, and a transmission unit 106. The low-speed signal phase modulation unit 105 corresponds to the low-speed signal modulation unit of the present invention.
Thelight source unit 101 emits CW (Continuous Wave) light. For the light source unit 101, for example, a DFB (Distributed Feedback) laser or the like is used.
The high-speedsignal output unit 102 outputs a digital signal having a predetermined frequency (first signal: hereinafter referred to as a high-speed signal). The high-speed signal output unit 102 outputs, for example, a 40 Gbps signal.
The low speedsignal output unit 103 outputs a digital signal having a frequency lower than that of the high speed signal (second signal: hereinafter referred to as a low speed signal). The low-speed signal output unit 103 outputs a signal of 10 Gbps, for example.
The high-speed signalphase modulation unit 104 performs phase modulation of CW light according to the high-speed signal.
The low-speed signalphase modulation unit 105 performs phase modulation of the optical signal phase-modulated by the high-speed signal phase modulation unit 104 according to the low-speed signal.
Thetransmission unit 106 transmits the optical signal subjected to phase modulation by the high-speed signal phase modulation unit 104 and the low-speed signal phase modulation unit 105 to the reception device 200.
(第1の実施形態)
まず、本発明の第1の実施形態について説明する。
図1は、本発明の第1の実施形態に従った光伝送システムの構成を示す概略ブロック図である。
光伝送システムは、送信装置100と受信装置200とを備える。
送信装置100は、光源部101と、高速信号出力部102と、低速信号出力部103と、高速信号位相変調部104と、低速信号位相変調部105と、送信部106とを備える。なお、低速信号位相変調部105は本発明の低速信号変調部に相当する。
光源部101は、CW(Continuous Wave:無変調連続波)光を発出する。光源部101には、例えばDFB(Distributed Feedback:分布帰還)レーザ等を用いる。
高速信号出力部102は、所定の周波数のデジタル信号(第1の信号:以下、高速信号とする)を出力する。高速信号出力部102は、例えば40Gbpsの信号を出力する。
低速信号出力部103は、高速信号より低い周波数のデジタル信号(第2の信号:以下、低速信号とする)を出力する。低速信号出力部103は、例えば10Gbpsの信号を出力する。
高速信号位相変調部104は、高速信号に応じてCW光の位相変調を行う。
低速信号位相変調部105は、低速信号に応じて、高速信号位相変調部104が位相変調した光信号の位相変調を行う。
送信部106は、高速信号位相変調部104および低速信号位相変調部105でそれぞれ位相変調を行った光信号を受信装置200に送信する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, a first embodiment of the present invention will be described.
FIG. 1 is a schematic block diagram showing a configuration of an optical transmission system according to the first embodiment of the present invention.
The optical transmission system includes a
The
The
The high-speed
The low speed
The high-speed signal
The low-speed signal
The
受信装置200は、光分岐部201と、遅延干渉部202と、光検出部203と、整流部204と、低速信号デコード部205と、位相変調部206と、高速光受信部207とを備える。なお、低速信号デコード部205は本発明の低速信号取得部に相当する。また、位相変調部206および高速光受信部207は本発明の高速信号取得部に相当する。
光分岐部201は、送信装置100から光信号を取得し、取得した光信号を分岐して遅延干渉部202と位相変調部206とに分配する。光分岐部201は、例えば光カプラ等を用いて光信号の分配を行う。
遅延干渉部202は、分配された光信号と、当該光信号を遅延させた光信号とを重ね合わせた干渉光を出力する。遅延干渉部202には、例えばマッハツェンダ型遅延干渉計等を用いる。
光検出部203は、遅延干渉部202が出力する光信号を電気信号に変換する。
整流部204は、光検出部203が変換した電気信号を全波整流する。
低速信号デコード部205は、全波整流した電気信号をデコードして低速信号を取得する。低速信号デコード部205は入力される電気信号のパルスの立ち下がりのエッジにおいて出力信号のパルスレベルを変化させることでデコードを行う。低速信号デコード部205には、例えばトグル型フリップフロップ等を用いる。
位相変調部206は、光分岐部201から分配された光信号を、低速信号デコード部205が取得した低速信号に応じて位相変調する。このとき、位相変調部206は送信装置100の低速信号位相変調部105と逆の論理で位相変調を行う。ここで、低速信号位相変調部105と逆の論理での位相変調とは、次に述べることを示している。例えば低速信号位相変調部105と位相変調部206とに同じ信号が入力された場合に、位相変調部206は、低速信号位相変調部105が出力する光信号と位相変調部206自身が出力する光信号との間の位相のずれの差がπとなるように位相変調を行う。
高速光受信部207は、位相変調部206が位相変調した光信号を受信し、高速信号を取得する。高速光受信部207には、例えば光検出回路と位相変調デコード回路とを組み合わせた回路等を用いる。 The receivingapparatus 200 includes an optical branching unit 201, a delay interference unit 202, a light detecting unit 203, a rectifying unit 204, a low-speed signal decoding unit 205, a phase modulating unit 206, and a high-speed optical receiving unit 207. The low speed signal decoding unit 205 corresponds to the low speed signal acquisition unit of the present invention. The phase modulation unit 206 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
The optical branchingunit 201 acquires an optical signal from the transmission apparatus 100, branches the acquired optical signal, and distributes the optical signal to the delay interference unit 202 and the phase modulation unit 206. The optical branching unit 201 distributes an optical signal using, for example, an optical coupler.
Thedelay interference unit 202 outputs interference light obtained by superimposing the distributed optical signal and the optical signal obtained by delaying the optical signal. For the delay interference unit 202, for example, a Mach-Zehnder delay interferometer or the like is used.
Thelight detection unit 203 converts the optical signal output from the delay interference unit 202 into an electrical signal.
Therectification unit 204 performs full-wave rectification on the electrical signal converted by the light detection unit 203.
The low-speedsignal decoding unit 205 decodes the full-wave rectified electrical signal to obtain a low-speed signal. The low-speed signal decoding unit 205 performs decoding by changing the pulse level of the output signal at the falling edge of the pulse of the input electric signal. For the low-speed signal decoding unit 205, for example, a toggle flip-flop is used.
Thephase modulation unit 206 performs phase modulation on the optical signal distributed from the optical branching unit 201 according to the low-speed signal acquired by the low-speed signal decoding unit 205. At this time, the phase modulation unit 206 performs phase modulation with a logic opposite to that of the low-speed signal phase modulation unit 105 of the transmission apparatus 100. Here, the phase modulation with the logic opposite to that of the low-speed signal phase modulation unit 105 indicates the following. For example, when the same signal is input to the low-speed signal phase modulation unit 105 and the phase modulation unit 206, the phase modulation unit 206 outputs the optical signal output from the low-speed signal phase modulation unit 105 and the light output from the phase modulation unit 206 itself. Phase modulation is performed so that the difference in phase shift from the signal is π.
The high-speedoptical receiver 207 receives the optical signal phase-modulated by the phase modulator 206 and acquires a high-speed signal. For the high-speed optical receiver 207, for example, a circuit combining a photodetection circuit and a phase modulation decoding circuit is used.
光分岐部201は、送信装置100から光信号を取得し、取得した光信号を分岐して遅延干渉部202と位相変調部206とに分配する。光分岐部201は、例えば光カプラ等を用いて光信号の分配を行う。
遅延干渉部202は、分配された光信号と、当該光信号を遅延させた光信号とを重ね合わせた干渉光を出力する。遅延干渉部202には、例えばマッハツェンダ型遅延干渉計等を用いる。
光検出部203は、遅延干渉部202が出力する光信号を電気信号に変換する。
整流部204は、光検出部203が変換した電気信号を全波整流する。
低速信号デコード部205は、全波整流した電気信号をデコードして低速信号を取得する。低速信号デコード部205は入力される電気信号のパルスの立ち下がりのエッジにおいて出力信号のパルスレベルを変化させることでデコードを行う。低速信号デコード部205には、例えばトグル型フリップフロップ等を用いる。
位相変調部206は、光分岐部201から分配された光信号を、低速信号デコード部205が取得した低速信号に応じて位相変調する。このとき、位相変調部206は送信装置100の低速信号位相変調部105と逆の論理で位相変調を行う。ここで、低速信号位相変調部105と逆の論理での位相変調とは、次に述べることを示している。例えば低速信号位相変調部105と位相変調部206とに同じ信号が入力された場合に、位相変調部206は、低速信号位相変調部105が出力する光信号と位相変調部206自身が出力する光信号との間の位相のずれの差がπとなるように位相変調を行う。
高速光受信部207は、位相変調部206が位相変調した光信号を受信し、高速信号を取得する。高速光受信部207には、例えば光検出回路と位相変調デコード回路とを組み合わせた回路等を用いる。 The receiving
The optical branching
The
The
The
The low-speed
The
The high-speed
上述した構成の光伝送システムにおいて、送信装置100の高速信号位相変調部104は、高速信号出力部102が出力する高速信号に応じて光源部101が出力するCW光を位相変調した光信号を出力する。低速信号位相変調部105は、高速信号位相変調部104が出力した光信号を低速信号出力部103が出力する低速信号に応じて位相変調する。送信部106は低速信号位相変調部105が出力する光信号を受信装置200に送信する。
受信装置200の遅延干渉部202は、光分岐部201が分岐した一方の光信号の遅延干渉を行い、干渉光を出力する。低速信号デコード部205は、光検出部203で干渉光から変換され、整流部204で全波整流された電気信号から低速信号を取得する。
位相変調部206は、光分岐部201が分岐した他方の光信号を、低速信号デコード部205が取得した低速信号に応じて位相変調する。高速光受信部207は、位相変調部206で位相変調した光信号を受信して高速信号を取得する。
これにより光伝送システムは、単一波長スロットに単峰的なスペクトル形状で速度の異なる複数の信号を多重する。 In the optical transmission system configured as described above, the high-speed signalphase modulation unit 104 of the transmission apparatus 100 outputs an optical signal obtained by phase-modulating the CW light output from the light source unit 101 in accordance with the high-speed signal output from the high-speed signal output unit 102. To do. The low-speed signal phase modulation unit 105 phase-modulates the optical signal output from the high-speed signal phase modulation unit 104 according to the low-speed signal output from the low-speed signal output unit 103. The transmission unit 106 transmits the optical signal output from the low-speed signal phase modulation unit 105 to the reception device 200.
Thedelay interference unit 202 of the receiving apparatus 200 performs delay interference of one optical signal branched by the optical branching unit 201 and outputs interference light. The low-speed signal decoding unit 205 acquires a low-speed signal from the electric signal converted from the interference light by the light detection unit 203 and full-wave rectified by the rectification unit 204.
Thephase modulation unit 206 phase-modulates the other optical signal branched by the optical branching unit 201 according to the low-speed signal acquired by the low-speed signal decoding unit 205. The high-speed optical receiver 207 receives the optical signal phase-modulated by the phase modulator 206 and acquires a high-speed signal.
Thus, the optical transmission system multiplexes a plurality of signals having different velocities with a unimodal spectrum shape in a single wavelength slot.
受信装置200の遅延干渉部202は、光分岐部201が分岐した一方の光信号の遅延干渉を行い、干渉光を出力する。低速信号デコード部205は、光検出部203で干渉光から変換され、整流部204で全波整流された電気信号から低速信号を取得する。
位相変調部206は、光分岐部201が分岐した他方の光信号を、低速信号デコード部205が取得した低速信号に応じて位相変調する。高速光受信部207は、位相変調部206で位相変調した光信号を受信して高速信号を取得する。
これにより光伝送システムは、単一波長スロットに単峰的なスペクトル形状で速度の異なる複数の信号を多重する。 In the optical transmission system configured as described above, the high-speed signal
The
The
Thus, the optical transmission system multiplexes a plurality of signals having different velocities with a unimodal spectrum shape in a single wavelength slot.
次に、光伝送システムの動作を説明する。
まず、送信装置100の高速信号位相変調部104は、光源部101が出力するCW光を、高速信号出力部102が出力する高速信号で位相変調する。このとき、位相シフト量はπとする。
図2は、高速信号位相変調部104の位相変調に伴う光信号の位相の遷移を示す位相図である。
図2の横軸は光信号の同相成分の大きさを示し、縦軸は光信号の直交成分の大きさを示している。高速信号位相変調部104が位相シフト量をπとして位相変調した光信号は、図2に示すように、その位相が0とπとの2点を遷移する信号となる。すなわち、位相が同相成分軸上を遷移する。 Next, the operation of the optical transmission system will be described.
First, the high-speed signalphase modulation unit 104 of the transmission apparatus 100 phase-modulates the CW light output from the light source unit 101 with the high-speed signal output from the high-speed signal output unit 102. At this time, the phase shift amount is π.
FIG. 2 is a phase diagram showing the transition of the phase of the optical signal accompanying the phase modulation of the high-speed signalphase modulation unit 104.
The horizontal axis in FIG. 2 indicates the magnitude of the in-phase component of the optical signal, and the vertical axis indicates the magnitude of the quadrature component of the optical signal. The optical signal phase-modulated by the high-speed signalphase modulation unit 104 with the phase shift amount being π becomes a signal whose phase transitions between two points of 0 and π, as shown in FIG. That is, the phase transitions on the in-phase component axis.
まず、送信装置100の高速信号位相変調部104は、光源部101が出力するCW光を、高速信号出力部102が出力する高速信号で位相変調する。このとき、位相シフト量はπとする。
図2は、高速信号位相変調部104の位相変調に伴う光信号の位相の遷移を示す位相図である。
図2の横軸は光信号の同相成分の大きさを示し、縦軸は光信号の直交成分の大きさを示している。高速信号位相変調部104が位相シフト量をπとして位相変調した光信号は、図2に示すように、その位相が0とπとの2点を遷移する信号となる。すなわち、位相が同相成分軸上を遷移する。 Next, the operation of the optical transmission system will be described.
First, the high-speed signal
FIG. 2 is a phase diagram showing the transition of the phase of the optical signal accompanying the phase modulation of the high-speed signal
The horizontal axis in FIG. 2 indicates the magnitude of the in-phase component of the optical signal, and the vertical axis indicates the magnitude of the quadrature component of the optical signal. The optical signal phase-modulated by the high-speed signal
次に、低速信号位相変調部105は、高速信号位相変調部104が出力する光信号を、低速信号出力部103が出力する低速信号で位相変調する。このとき、位相シフト量はπ/2とする。
図3は、低速信号位相変調部105の位相変調に伴う光信号の位相の遷移を示す位相図である。
図3の横軸は光信号の同相成分の大きさを示し、縦軸は光信号の直交成分の大きさを示している。低速信号位相変調部105が位相シフト量をπ/2として高速信号位相変調部104が出力する光信号をさらに位相変調すると、変調後の信号は、図3に示すように、その位相が0とπ/2とπと3π/2との4点を遷移する信号となる。このとき、低速信号の切り替わりに対応して、高速信号の位相遷移は、同相成分軸上の位相遷移と直交成分軸上の位相遷移とがスイッチングする形となる。
低速信号位相変調部105が光信号を出力すると、送信部106は、この光信号を受信装置200に送信する。 Next, the low-speed signalphase modulation unit 105 phase-modulates the optical signal output from the high-speed signal phase modulation unit 104 with the low-speed signal output from the low-speed signal output unit 103. At this time, the phase shift amount is π / 2.
FIG. 3 is a phase diagram showing transition of the phase of the optical signal accompanying the phase modulation of the low-speed signalphase modulation unit 105.
The horizontal axis in FIG. 3 indicates the magnitude of the in-phase component of the optical signal, and the vertical axis indicates the magnitude of the quadrature component of the optical signal. When the low-speed signalphase modulation unit 105 further phase-modulates the optical signal output from the high-speed signal phase modulation unit 104 with a phase shift amount of π / 2, the modulated signal has a phase of 0 as shown in FIG. It becomes a signal that transitions at four points of π / 2, π, and 3π / 2. At this time, the phase transition of the high-speed signal is switched between the phase transition on the in-phase component axis and the phase transition on the orthogonal component axis in response to the switching of the low-speed signal.
When the low-speed signalphase modulation unit 105 outputs an optical signal, the transmission unit 106 transmits the optical signal to the reception device 200.
図3は、低速信号位相変調部105の位相変調に伴う光信号の位相の遷移を示す位相図である。
図3の横軸は光信号の同相成分の大きさを示し、縦軸は光信号の直交成分の大きさを示している。低速信号位相変調部105が位相シフト量をπ/2として高速信号位相変調部104が出力する光信号をさらに位相変調すると、変調後の信号は、図3に示すように、その位相が0とπ/2とπと3π/2との4点を遷移する信号となる。このとき、低速信号の切り替わりに対応して、高速信号の位相遷移は、同相成分軸上の位相遷移と直交成分軸上の位相遷移とがスイッチングする形となる。
低速信号位相変調部105が光信号を出力すると、送信部106は、この光信号を受信装置200に送信する。 Next, the low-speed signal
FIG. 3 is a phase diagram showing transition of the phase of the optical signal accompanying the phase modulation of the low-speed signal
The horizontal axis in FIG. 3 indicates the magnitude of the in-phase component of the optical signal, and the vertical axis indicates the magnitude of the quadrature component of the optical signal. When the low-speed signal
When the low-speed signal
受信装置200の光分岐部201は、送信装置100から光信号を取得すると、取得した光信号を2つに分岐し、遅延干渉部202と位相変調部206とに出力する。遅延干渉部202は、分岐した一方の光信号の遅延干渉を行う。このとき、遅延量は高速信号の1シンボル時間とする。これにより、遅延干渉部202が出力する光信号は、位相差が0である場合の光強度と、位相差がπ/2または3π/2である場合の光強度と、位相差がπである場合の光強度の3種類の光強度を有する光信号となる。低速信号の値が切り替わった時のみ位相差はπ/2または3π/2となる。
遅延干渉部202が光信号を出力すると、光検出部203は、この光信号を電気信号に変換する。光検出部203は、光信号の強度が、位相差が0であるときの強度の場合に電気信号の電圧をVとし、位相差がπ/2または3π/2であるときの強度の場合に電気信号の電圧を0とし、位相差がπであるときの強度の場合に電気信号の電圧を-Vとする。
整流部204は、光検出部203が出力した電気信号を全波整流する。すなわち、光検出部203が出力した電気信号の絶対値となる電気信号を出力する。これにより、低速信号のシンボル論理の切り替わりがあるところで電圧が0となり、それ以外では電圧がVとなる。
整流部204が全波整流した電気信号を出力すると、低速信号デコード部205は、(後述するように、高速信号のビット変化に伴う高速の波形変動を除去した上で)全波整流した電気信号のパルスの立ち下がりのエッジにおいて出力信号のパルスレベルを変化させることでデコードを行う。これにより得られる出力信号は低速信号と同じ信号となる。 When the optical branchingunit 201 of the receiving device 200 acquires the optical signal from the transmitting device 100, the optical branching unit 201 branches the acquired optical signal into two, and outputs them to the delay interference unit 202 and the phase modulation unit 206. The delay interference unit 202 performs delay interference of one of the branched optical signals. At this time, the delay amount is one symbol time of the high-speed signal. Accordingly, the optical signal output from the delay interference unit 202 has a light intensity when the phase difference is 0, a light intensity when the phase difference is π / 2 or 3π / 2, and a phase difference of π. It becomes an optical signal having three kinds of light intensities. Only when the value of the low-speed signal is switched, the phase difference becomes π / 2 or 3π / 2.
When thedelay interference unit 202 outputs an optical signal, the light detection unit 203 converts the optical signal into an electrical signal. The light detection unit 203 sets the voltage of the electric signal to V when the intensity of the optical signal is the intensity when the phase difference is 0, and when the intensity is when the phase difference is π / 2 or 3π / 2. When the voltage of the electric signal is 0 and the intensity is when the phase difference is π, the voltage of the electric signal is −V.
Therectification unit 204 performs full-wave rectification on the electrical signal output from the light detection unit 203. That is, an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203 is output. As a result, the voltage becomes 0 when the symbol logic of the low-speed signal is switched, and the voltage becomes V otherwise.
When therectification unit 204 outputs the full-wave rectified electric signal, the low-speed signal decoding unit 205 performs the full-wave rectification of the electric signal (after removing high-speed waveform fluctuations associated with bit changes of the high-speed signal, as will be described later). Decoding is performed by changing the pulse level of the output signal at the falling edge of the pulse. The output signal thus obtained is the same signal as the low speed signal.
遅延干渉部202が光信号を出力すると、光検出部203は、この光信号を電気信号に変換する。光検出部203は、光信号の強度が、位相差が0であるときの強度の場合に電気信号の電圧をVとし、位相差がπ/2または3π/2であるときの強度の場合に電気信号の電圧を0とし、位相差がπであるときの強度の場合に電気信号の電圧を-Vとする。
整流部204は、光検出部203が出力した電気信号を全波整流する。すなわち、光検出部203が出力した電気信号の絶対値となる電気信号を出力する。これにより、低速信号のシンボル論理の切り替わりがあるところで電圧が0となり、それ以外では電圧がVとなる。
整流部204が全波整流した電気信号を出力すると、低速信号デコード部205は、(後述するように、高速信号のビット変化に伴う高速の波形変動を除去した上で)全波整流した電気信号のパルスの立ち下がりのエッジにおいて出力信号のパルスレベルを変化させることでデコードを行う。これにより得られる出力信号は低速信号と同じ信号となる。 When the optical branching
When the
The
When the
低速信号デコード部205が低速信号を再現すると、位相変調部206は低速信号位相変調部105と逆の論理で、光分岐部201が分岐した他方の光信号を、低速信号デコード部205で再現した低速信号に応じて位相変調する。このとき、位相シフト量は、送信装置100の低速信号位相変調部105と同じくπ/2とする。これにより、高速信号位相変調部104が高速信号に基づいて位相変調を行った信号と同じ信号を得ることができる。
位相変調部206が位相変調を行うと、高速光受信部207は、位相変調した信号に対して、高速信号位相変調部104が行う変調に対応する復調を行って電気信号に変換することで高速信号を取得する。
これにより、受信装置200は高速信号と低速信号を分離し、それぞれの信号を取得することができる。
以上が光伝送システムの動作である。 When the low-speedsignal decoding unit 205 reproduces the low-speed signal, the phase modulation unit 206 reproduces the other optical signal branched by the optical branching unit 201 by the low-speed signal decoding unit 205 with the reverse logic of the low-speed signal phase modulation unit 105. Phase modulation is performed according to a low-speed signal. At this time, the phase shift amount is set to π / 2 as in the low-speed signal phase modulation unit 105 of the transmission device 100. Thereby, the same signal as the signal which the high-speed signal phase modulation | alteration part 104 performed the phase modulation based on the high-speed signal can be obtained.
When thephase modulation unit 206 performs phase modulation, the high-speed optical reception unit 207 performs high-speed optical demodulation by performing demodulation corresponding to the modulation performed by the high-speed signal phase modulation unit 104 on the phase-modulated signal and converts it to an electrical signal. Get the signal.
Thereby, the receivingapparatus 200 can separate the high-speed signal and the low-speed signal and acquire each signal.
The above is the operation of the optical transmission system.
位相変調部206が位相変調を行うと、高速光受信部207は、位相変調した信号に対して、高速信号位相変調部104が行う変調に対応する復調を行って電気信号に変換することで高速信号を取得する。
これにより、受信装置200は高速信号と低速信号を分離し、それぞれの信号を取得することができる。
以上が光伝送システムの動作である。 When the low-speed
When the
Thereby, the receiving
The above is the operation of the optical transmission system.
以下に、具体的な信号の例を用いて光伝送システムの説明を行う。
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。
図4は、第1の実施形態における各処理部が出力する信号の波形を示す図である。なお、図4において、垂直方向に延びる点線で区分された各期間が低速信号の1シンボルビットに対応している。また、ここでは低速信号のビットが1,0,0,0,1,1,0,1,1,1と順次変化する場合についての例を示してある。
図4(a)は、高速信号位相変調部104が出力する光信号の位相の遷移を示す。
図4(a)の縦軸は位相を示し、横軸は時間を示す。高速信号位相変調部104が出力する光信号の位相は0とπとを遷移する。
図4(b)は、低速信号位相変調部105が出力する光信号の位相の遷移を示す。
図4(b)の縦軸は位相を示し、横軸は時間を示す。低速信号位相変調部105が出力する光信号の位相は0、π/2、π、3π/2を遷移する。また、低速信号のビットが1となる期間で位相がπ/2と3π/2とを遷移し、低速信号のビットが0となる期間で位相が0とπとを遷移する。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speedsignal output unit 102 outputs a high-speed signal of 40 Gbps and the low-speed signal output unit 103 outputs a low-speed signal of 10 Gbps will be described.
FIG. 4 is a diagram illustrating a waveform of a signal output from each processing unit according to the first embodiment. In FIG. 4, each period divided by a dotted line extending in the vertical direction corresponds to one symbol bit of the low-speed signal. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
FIG. 4A shows the phase transition of the optical signal output from the high-speedsignal phase modulator 104.
In FIG. 4A, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the high-speed signalphase modulation unit 104 transitions between 0 and π.
FIG. 4B shows the phase transition of the optical signal output from the low-speedsignal phase modulator 105.
In FIG. 4B, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the low-speedsignal phase modulator 105 transitions between 0, π / 2, π, and 3π / 2. Further, the phase transitions between π / 2 and 3π / 2 during the period when the bit of the low-speed signal is 1, and the phase transitions between 0 and π during the period when the bit of the low-speed signal is 0.
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。
図4は、第1の実施形態における各処理部が出力する信号の波形を示す図である。なお、図4において、垂直方向に延びる点線で区分された各期間が低速信号の1シンボルビットに対応している。また、ここでは低速信号のビットが1,0,0,0,1,1,0,1,1,1と順次変化する場合についての例を示してある。
図4(a)は、高速信号位相変調部104が出力する光信号の位相の遷移を示す。
図4(a)の縦軸は位相を示し、横軸は時間を示す。高速信号位相変調部104が出力する光信号の位相は0とπとを遷移する。
図4(b)は、低速信号位相変調部105が出力する光信号の位相の遷移を示す。
図4(b)の縦軸は位相を示し、横軸は時間を示す。低速信号位相変調部105が出力する光信号の位相は0、π/2、π、3π/2を遷移する。また、低速信号のビットが1となる期間で位相がπ/2と3π/2とを遷移し、低速信号のビットが0となる期間で位相が0とπとを遷移する。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speed
FIG. 4 is a diagram illustrating a waveform of a signal output from each processing unit according to the first embodiment. In FIG. 4, each period divided by a dotted line extending in the vertical direction corresponds to one symbol bit of the low-speed signal. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
FIG. 4A shows the phase transition of the optical signal output from the high-speed
In FIG. 4A, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the high-speed signal
FIG. 4B shows the phase transition of the optical signal output from the low-speed
In FIG. 4B, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the low-speed
図4(c)は、光検出部203が出力する電気信号の電圧の遷移を示す。
図4(c)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した光信号すなわち低速信号位相変調部105が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、光検出部203の出力信号は、低速信号位相変調部105が出力する光信号の隣接するシンボル間の位相差に応じて電圧がV、または、-Vとなり、低速信号のシンボルビットの切り替わり点においてのみ電圧が0となる。
図4(d)は、整流部204が出力する電気信号の電圧の遷移を示す。
図4(d)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、低速信号のシンボルビットの切り替わり点においてのみ電圧が0となり、それ以外の期間においては電圧がVとなる。 FIG. 4C shows the voltage transition of the electric signal output from thelight detection unit 203.
In FIG. 4C, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from thelight detection unit 203 transitions between V, 0, and −V. The electrical signal output from the light detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal. The delay interference unit 202 performs delay interference of the optical signal branched by the optical branching unit 201, that is, the optical signal output from the low-speed signal phase modulation unit 105. At this time, when the phase difference between adjacent symbols is 0, the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201. When the phase difference between adjacent symbols is π, the intensity of the optical signal output from the delay interference unit 202 is zero. When the phase difference between adjacent symbols is π / 2 or 3π / 2, the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to −V when the intensity of the input optical signal is 0. Therefore, the output signal of the light detection unit 203 has a voltage of V or −V according to the phase difference between adjacent symbols of the optical signal output from the low-speed signal phase modulation unit 105, and the symbol bits of the low-speed signal are switched. The voltage is zero only at the points.
FIG. 4D shows the transition of the voltage of the electric signal output from the rectifyingunit 204.
In FIG. 4D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifyingunit 204 transitions between V and 0. The rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Accordingly, the voltage is 0 only at the switching point of the symbol bit of the low-speed signal, and the voltage is V in the other periods.
図4(c)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した光信号すなわち低速信号位相変調部105が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、光検出部203の出力信号は、低速信号位相変調部105が出力する光信号の隣接するシンボル間の位相差に応じて電圧がV、または、-Vとなり、低速信号のシンボルビットの切り替わり点においてのみ電圧が0となる。
図4(d)は、整流部204が出力する電気信号の電圧の遷移を示す。
図4(d)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、低速信号のシンボルビットの切り替わり点においてのみ電圧が0となり、それ以外の期間においては電圧がVとなる。 FIG. 4C shows the voltage transition of the electric signal output from the
In FIG. 4C, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the
FIG. 4D shows the transition of the voltage of the electric signal output from the rectifying
In FIG. 4D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifying
そのため、低速信号デコード部205は整流部204が出力する電気信号のパルスの立ち下がりのエッジにおいて出力信号のパルスレベルを変化させる、すなわち電圧が0となる点で出力信号のパルスレベルを変化させることで、光分岐部201が分岐した光信号から低速信号を取り出すことができる。なお、整流部204が出力する電気信号には、高速信号のビット変化に伴う高速の波形変動の影響がノイズとなって現れる。これにより低速信号デコード部205がノイズを誤って認識してしまう可能性がある。そのため、整流部204が出力する電気信号の帯域を例えばローパスフィルタで低速信号レベルの帯域に制限することでノイズを除去するとよい。
Therefore, the low-speed signal decoding unit 205 changes the pulse level of the output signal at the falling edge of the pulse of the electric signal output from the rectifying unit 204, that is, changes the pulse level of the output signal at a point where the voltage becomes zero. Thus, a low-speed signal can be extracted from the optical signal branched by the optical branching unit 201. It should be noted that the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise. As a result, there is a possibility that the low-speed signal decoding unit 205 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
このように、本実施形態によれば、送信装置100は、高速信号に応じて位相変調した光信号に対して位相変調を用いて低速信号を重畳する。受信装置200は、遅延干渉を行い、干渉光を電気信号に変換して低速信号を取得する。受信装置200は、送信装置100から取得した光信号をこの光信号から取得した低速信号に応じて位相変調し、デコードすることで高速信号を再現する。これにより、高速信号、および、低速信号を多重することができる。
また本実施形態によれば、送信装置100は、同一の波長の光信号を用いて高速信号と低速信号とを重畳する。これにより、多重信号が単峰性のスペクトルとなるため、複数の信号を単一の波長スロット内に収めることができる。
また本実施形態によれば、送信装置100は、高速信号の位相変調を高速信号位相変調部104で行い、低速信号の位相変調を低速信号位相変調部105で行う。これにより、必要なときに低速信号位相変調部105を追加するなど、既存の光伝送システムに必要部位を追加することで簡単に実装することができる。
また本実施形態によれば、送信装置100は、低速信号の重畳を位相変調で行うため、高速信号位相変調部104が出力する光信号の強度を失わない。また、受信装置200で低速信号を再現して重畳された信号から低速信号部分を除去するため、光強度の情報を失わない。これにより、高速信号に応じて変調した光信号の長距離伝送特性を大きく失うことなく低速信号を多重することができる。 As described above, according to the present embodiment, thetransmission device 100 superimposes the low-speed signal on the optical signal phase-modulated according to the high-speed signal using the phase modulation. The receiving apparatus 200 performs delayed interference, converts the interference light into an electrical signal, and acquires a low-speed signal. The receiving device 200 reproduces a high-speed signal by phase-modulating and decoding the optical signal acquired from the transmitting device 100 according to the low-speed signal acquired from the optical signal. Thereby, a high speed signal and a low speed signal can be multiplexed.
Further, according to the present embodiment, thetransmission device 100 superimposes a high-speed signal and a low-speed signal using optical signals having the same wavelength. Thereby, since the multiplexed signal has a unimodal spectrum, a plurality of signals can be accommodated in a single wavelength slot.
Further, according to the present embodiment, thetransmission apparatus 100 performs the phase modulation of the high speed signal by the high speed signal phase modulation unit 104 and performs the phase modulation of the low speed signal by the low speed signal phase modulation unit 105. Accordingly, it is possible to easily implement by adding a necessary part to an existing optical transmission system, such as adding a low-speed signal phase modulation unit 105 when necessary.
Further, according to the present embodiment, thetransmission device 100 performs superimposition of the low-speed signals by phase modulation, so that the intensity of the optical signal output from the high-speed signal phase modulation unit 104 is not lost. In addition, since the low-speed signal portion is removed from the superimposed signal by reproducing the low-speed signal by the receiving apparatus 200, the information on the light intensity is not lost. As a result, it is possible to multiplex a low-speed signal without greatly losing the long-distance transmission characteristic of the optical signal modulated according to the high-speed signal.
また本実施形態によれば、送信装置100は、同一の波長の光信号を用いて高速信号と低速信号とを重畳する。これにより、多重信号が単峰性のスペクトルとなるため、複数の信号を単一の波長スロット内に収めることができる。
また本実施形態によれば、送信装置100は、高速信号の位相変調を高速信号位相変調部104で行い、低速信号の位相変調を低速信号位相変調部105で行う。これにより、必要なときに低速信号位相変調部105を追加するなど、既存の光伝送システムに必要部位を追加することで簡単に実装することができる。
また本実施形態によれば、送信装置100は、低速信号の重畳を位相変調で行うため、高速信号位相変調部104が出力する光信号の強度を失わない。また、受信装置200で低速信号を再現して重畳された信号から低速信号部分を除去するため、光強度の情報を失わない。これにより、高速信号に応じて変調した光信号の長距離伝送特性を大きく失うことなく低速信号を多重することができる。 As described above, according to the present embodiment, the
Further, according to the present embodiment, the
Further, according to the present embodiment, the
Further, according to the present embodiment, the
以上、図面を参照してこの発明の第1の実施形態について詳しく説明したが、具体的な構成は上述のものに限られることはなく、この発明の要旨を逸脱しない範囲内において様々な設計変更等をすることが可能である。
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 The first embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 The first embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
なお、本実施形態では、遅延干渉部202の遅延量が高速信号の1シンボル時間に相当する場合を説明したが、これに限られない。例えば遅延量を低速信号の1シンボル時間とすることで、低速信号デコード部205に入力される電気信号の電圧が0となる時間を長くし、低速信号デコード部205の識別の余裕を広げ、識別誤りの可能性を低下させても良い。
In the present embodiment, the case where the delay amount of the delay interference unit 202 corresponds to one symbol time of a high-speed signal has been described, but the present invention is not limited to this. For example, by setting the delay amount to one symbol time of the low-speed signal, the time for the voltage of the electric signal input to the low-speed signal decoding unit 205 to become zero is lengthened, and the identification margin of the low-speed signal decoding unit 205 is widened. The possibility of error may be reduced.
また、本実施形態では、高速信号位相変調部104が位相変調を行う場合を説明したが、これに限られず、高速信号位相変調部104は差動位相偏移変調を行っても良い。この場合、高速信号位相変調部104に、例えばLiNbO3マッハツェンダ変調器等を用い、高速光受信部207に、例えばマッハツェンダ型遅延干渉計と光検出回路と位相変調デコード回路とを組み合わせた回路や、コヒーレント光受信方式に基づく受信回路等を用いることで、送信装置100および受信装置200を実装することができる。
In this embodiment, the case where the high-speed signal phase modulation unit 104 performs phase modulation has been described. However, the present invention is not limited to this, and the high-speed signal phase modulation unit 104 may perform differential phase shift keying. In this case, for example, a LiNbO 3 Mach-Zehnder modulator or the like is used as the high-speed signal phase modulation unit 104, and a high-speed optical reception unit 207 is combined with, for example, a Mach-Zehnder type delay interferometer, a photodetector circuit, and a phase modulation decoding circuit, By using a receiving circuit or the like based on the coherent light receiving method, the transmitting device 100 and the receiving device 200 can be mounted.
(第2の実施形態)
次に、本発明の第2の実施形態について説明する。第2の実施形態は、送信装置100で低速信号のプリコードを行うことで、受信装置200で低速信号のデコードを行わずに低速信号を取得する光伝送システムの例である。
第1の実施形態で説明した受信装置200の低速信号デコード部205は、入力信号のパルスの立ち下がりに応答して出力信号のレベルを変化させる。したがって、ビット誤りが存在すると、誤ったビット以降のビットが反転した信号が出力されてしまう。そのため、受信した光信号に雑音が入ってしまう受信装置200において低速信号のデコードを行うと、バースト的に誤りが生じる。これにより、低速信号の誤り率が高くなるだけでなく、位相変調部206の出力結果も誤ってしまうため、高速信号の誤り率も高くなってしまう。そこで、受信装置200においてデコード処理を行わずに低速信号を取得することができれば、低速信号、高速信号ともに誤り率を低減させることができる。 (Second Embodiment)
Next, a second embodiment of the present invention will be described. The second embodiment is an example of an optical transmission system in which a low-speed signal is pre-coded by thetransmission device 100 and the low-speed signal is acquired without the reception device 200 decoding the low-speed signal.
The low-speedsignal decoding unit 205 of the receiving apparatus 200 described in the first embodiment changes the level of the output signal in response to the falling edge of the pulse of the input signal. Therefore, if a bit error exists, a signal in which the bits after the erroneous bit are inverted is output. For this reason, when a low-speed signal is decoded in the receiving apparatus 200 in which noise is included in the received optical signal, an error occurs in a burst manner. As a result, not only the error rate of the low-speed signal is increased, but also the output result of the phase modulation unit 206 is erroneous, so that the error rate of the high-speed signal is also increased. Therefore, if the low-speed signal can be acquired without performing decoding processing in the receiving apparatus 200, the error rate can be reduced for both the low-speed signal and the high-speed signal.
次に、本発明の第2の実施形態について説明する。第2の実施形態は、送信装置100で低速信号のプリコードを行うことで、受信装置200で低速信号のデコードを行わずに低速信号を取得する光伝送システムの例である。
第1の実施形態で説明した受信装置200の低速信号デコード部205は、入力信号のパルスの立ち下がりに応答して出力信号のレベルを変化させる。したがって、ビット誤りが存在すると、誤ったビット以降のビットが反転した信号が出力されてしまう。そのため、受信した光信号に雑音が入ってしまう受信装置200において低速信号のデコードを行うと、バースト的に誤りが生じる。これにより、低速信号の誤り率が高くなるだけでなく、位相変調部206の出力結果も誤ってしまうため、高速信号の誤り率も高くなってしまう。そこで、受信装置200においてデコード処理を行わずに低速信号を取得することができれば、低速信号、高速信号ともに誤り率を低減させることができる。 (Second Embodiment)
Next, a second embodiment of the present invention will be described. The second embodiment is an example of an optical transmission system in which a low-speed signal is pre-coded by the
The low-speed
図5は、本発明の第2の実施形態に従った光伝送システムの構成を示す概略ブロック図である。
第2の実施形態に従った光伝送システムの構成は、第1の実施形態に加えて送信装置100にさらにプリコード部111を備え、受信装置200の低速信号デコード部205の代わりに低速信号検波部211を備える構成である。なお、その他の処理部は第1の実施形態の光伝送システムの構成と同じであるため、同一の符号を用いて説明する。プリコード部111および低速信号位相変調部105は本発明の低速信号変調部に相当する。また、低速信号検波部211は本発明の低速信号取得部に相当する。また、位相変調部206および高速光受信部207は本発明の高速信号取得部に相当する。
本実施形態において、送信装置100のプリコード部111は低速信号のプリコードを行う。プリコード部111は入力される電気信号のビットが1である場合(所定のレベルであるとき)に出力信号のパルスレベルを変化させることでプリコードを行う。低速信号位相変調部105はプリコードを行った低速信号に応じて高速信号位相変調部104が位相変調した光信号の位相変調を行う。また、受信装置200の低速信号検波部211はデコード処理を行わずに、整流部204が全波整流した電気信号を検波して低速信号を取得する。 FIG. 5 is a schematic block diagram showing the configuration of the optical transmission system according to the second embodiment of the present invention.
The configuration of the optical transmission system according to the second embodiment includes aprecoding unit 111 in addition to the transmission device 100 in addition to the first embodiment, and low-speed signal detection instead of the low-speed signal decoding unit 205 of the reception device 200. It is the structure provided with the part 211. The other processing units are the same as those of the optical transmission system according to the first embodiment, and therefore will be described using the same reference numerals. The precoding unit 111 and the low-speed signal phase modulation unit 105 correspond to the low-speed signal modulation unit of the present invention. The low speed signal detection unit 211 corresponds to the low speed signal acquisition unit of the present invention. The phase modulation unit 206 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
In the present embodiment, theprecoding unit 111 of the transmission device 100 performs low-code signal precoding. The precoding unit 111 performs precoding by changing the pulse level of the output signal when the bit of the input electric signal is 1 (when it is at a predetermined level). The low-speed signal phase modulation unit 105 performs phase modulation of the optical signal phase-modulated by the high-speed signal phase modulation unit 104 according to the low-speed signal subjected to precoding. Further, the low-speed signal detection unit 211 of the reception device 200 detects the electric signal that has been full-wave rectified by the rectification unit 204 without performing decoding processing, and acquires a low-speed signal.
第2の実施形態に従った光伝送システムの構成は、第1の実施形態に加えて送信装置100にさらにプリコード部111を備え、受信装置200の低速信号デコード部205の代わりに低速信号検波部211を備える構成である。なお、その他の処理部は第1の実施形態の光伝送システムの構成と同じであるため、同一の符号を用いて説明する。プリコード部111および低速信号位相変調部105は本発明の低速信号変調部に相当する。また、低速信号検波部211は本発明の低速信号取得部に相当する。また、位相変調部206および高速光受信部207は本発明の高速信号取得部に相当する。
本実施形態において、送信装置100のプリコード部111は低速信号のプリコードを行う。プリコード部111は入力される電気信号のビットが1である場合(所定のレベルであるとき)に出力信号のパルスレベルを変化させることでプリコードを行う。低速信号位相変調部105はプリコードを行った低速信号に応じて高速信号位相変調部104が位相変調した光信号の位相変調を行う。また、受信装置200の低速信号検波部211はデコード処理を行わずに、整流部204が全波整流した電気信号を検波して低速信号を取得する。 FIG. 5 is a schematic block diagram showing the configuration of the optical transmission system according to the second embodiment of the present invention.
The configuration of the optical transmission system according to the second embodiment includes a
In the present embodiment, the
以下に、具体的な信号の例を用いて光伝送システムの説明を行う。
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。
図6は、第2の実施形態における各処理部が出力する信号の波形を示す図である。なお、ここでは低速信号のビットが0,1,0,0,1,0,1,1,0,0と順次変化する場合についての例を示してある。
図6(a)は、低速信号出力部103が出力する信号のビットの遷移を示す。
図6(a)の縦軸はビット値を示し、横軸は時間を示す。低速信号は1と0とを遷移する。
図6(b)は、プリコード部111が出力する信号のビットの遷移を示す。
図6(b)の縦軸はビット値を示し、横軸は時間を示す。プリコード部111の出力信号は1と0とを遷移する。プリコード部111は、低速信号のビットが1となる点で出力信号のビット値を反転させる。
図6(c)は、低速信号位相変調部105が出力する光信号の位相の遷移を示す。
図6(c)の縦軸は位相を示し、横軸は時間を示す。低速信号位相変調部105が出力する光信号の位相は0、π/2、π、3π/2を遷移する。また、プリコード部111の出力信号のビットが1となる期間で位相がπ/2と3π/2とを遷移し、プリコード部111の出力信号のビットが0となる期間で位相が0とπとを遷移する。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speedsignal output unit 102 outputs a high-speed signal of 40 Gbps and the low-speed signal output unit 103 outputs a low-speed signal of 10 Gbps will be described.
FIG. 6 is a diagram illustrating a waveform of a signal output from each processing unit according to the second embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 0, 1, 0, 0, 1, 0, 1, 1, 0, 0.
FIG. 6A shows bit transition of a signal output from the low-speedsignal output unit 103.
In FIG. 6A, the vertical axis indicates a bit value, and the horizontal axis indicates time. The low speed signal transitions between 1 and 0.
FIG. 6B shows bit transition of a signal output from theprecoding unit 111.
In FIG. 6B, the vertical axis indicates a bit value, and the horizontal axis indicates time. The output signal of theprecoding unit 111 transitions between 1 and 0. The precoding unit 111 inverts the bit value of the output signal when the bit of the low-speed signal becomes 1.
FIG. 6C shows the phase transition of the optical signal output from the low-speed signalphase modulation unit 105.
In FIG. 6C, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the low-speedsignal phase modulator 105 transitions between 0, π / 2, π, and 3π / 2. Also, the phase transitions between π / 2 and 3π / 2 during the period when the bit of the output signal of the precoding unit 111 is 1, and the phase is 0 during the period when the bit of the output signal of the precoding unit 111 is 0. Transition to π.
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。
図6は、第2の実施形態における各処理部が出力する信号の波形を示す図である。なお、ここでは低速信号のビットが0,1,0,0,1,0,1,1,0,0と順次変化する場合についての例を示してある。
図6(a)は、低速信号出力部103が出力する信号のビットの遷移を示す。
図6(a)の縦軸はビット値を示し、横軸は時間を示す。低速信号は1と0とを遷移する。
図6(b)は、プリコード部111が出力する信号のビットの遷移を示す。
図6(b)の縦軸はビット値を示し、横軸は時間を示す。プリコード部111の出力信号は1と0とを遷移する。プリコード部111は、低速信号のビットが1となる点で出力信号のビット値を反転させる。
図6(c)は、低速信号位相変調部105が出力する光信号の位相の遷移を示す。
図6(c)の縦軸は位相を示し、横軸は時間を示す。低速信号位相変調部105が出力する光信号の位相は0、π/2、π、3π/2を遷移する。また、プリコード部111の出力信号のビットが1となる期間で位相がπ/2と3π/2とを遷移し、プリコード部111の出力信号のビットが0となる期間で位相が0とπとを遷移する。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speed
FIG. 6 is a diagram illustrating a waveform of a signal output from each processing unit according to the second embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 0, 1, 0, 0, 1, 0, 1, 1, 0, 0.
FIG. 6A shows bit transition of a signal output from the low-speed
In FIG. 6A, the vertical axis indicates a bit value, and the horizontal axis indicates time. The low speed signal transitions between 1 and 0.
FIG. 6B shows bit transition of a signal output from the
In FIG. 6B, the vertical axis indicates a bit value, and the horizontal axis indicates time. The output signal of the
FIG. 6C shows the phase transition of the optical signal output from the low-speed signal
In FIG. 6C, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the low-speed
図6(d)は、光検出部203が出力する電気信号の電圧の遷移を示す。
図6(d)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した一方の光信号すなわち低速信号位相変調部105が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、光検出部203の出力信号は、低速信号のビットが1となった時点において電圧が0となり、その他では電圧はVまたは-Vとなる。
図6(e)は、整流部204が出力する電気信号の電圧の遷移を示す。
図6(e)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、整流部204が出力する電気信号は、低速信号のビットが1となった時点でその電圧が0となり、低速信号のビットが0の場合に電圧がVとなる。 FIG. 6D shows the voltage transition of the electrical signal output from thelight detection unit 203.
In FIG. 6D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from thelight detection unit 203 transitions between V, 0, and −V. The electrical signal output from the light detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal. The delay interference unit 202 performs delay interference of one optical signal branched by the optical branching unit 201, that is, the optical signal output from the low-speed signal phase modulation unit 105. At this time, when the phase difference between adjacent symbols is 0, the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201. When the phase difference between adjacent symbols is π, the intensity of the optical signal output from the delay interference unit 202 is zero. When the phase difference between adjacent symbols is π / 2 or 3π / 2, the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to −V when the intensity of the input optical signal is 0. Accordingly, the output signal of the light detection unit 203 has a voltage of 0 when the bit of the low-speed signal becomes 1, and the voltage is V or −V otherwise.
FIG. 6E shows the transition of the voltage of the electric signal output from the rectifyingunit 204.
In FIG. 6E, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifyingunit 204 transitions between V and 0. The rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Therefore, the voltage of the electrical signal output from the rectifying unit 204 is 0 when the bit of the low-speed signal becomes 1, and the voltage is V when the bit of the low-speed signal is 0.
図6(d)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した一方の光信号すなわち低速信号位相変調部105が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、光検出部203の出力信号は、低速信号のビットが1となった時点において電圧が0となり、その他では電圧はVまたは-Vとなる。
図6(e)は、整流部204が出力する電気信号の電圧の遷移を示す。
図6(e)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、整流部204が出力する電気信号は、低速信号のビットが1となった時点でその電圧が0となり、低速信号のビットが0の場合に電圧がVとなる。 FIG. 6D shows the voltage transition of the electrical signal output from the
In FIG. 6D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the
FIG. 6E shows the transition of the voltage of the electric signal output from the rectifying
In FIG. 6E, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifying
そのため、低速信号検波部211は整流部204が出力する電気信号の電圧が0となった時点で1を出力し、電圧がVの場合に0を出力することで、低速信号を取得することができる。なお、整流部204が出力する電気信号には、高速信号のビット変化に伴う高速の波形変動の影響がノイズとなって現れる。これにより低速信号検波部211がノイズを誤って認識してしまう可能性がある。そのため、整流部204が出力する電気信号の帯域を例えばローパスフィルタで低速信号レベルの帯域に制限することでノイズを除去するとよい。
Therefore, the low-speed signal detection unit 211 outputs 1 when the voltage of the electrical signal output from the rectification unit 204 becomes 0, and outputs 0 when the voltage is V, thereby acquiring a low-speed signal. it can. It should be noted that the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise. As a result, there is a possibility that the low-speed signal detection unit 211 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
このように、本実施形態によれば、送信装置100で低速信号をプリコードし、プリコードした低速信号に応じ、高速信号に応じて位相変調した光信号の位相変調を行う。これにより、受信装置200は低速信号のデコードを行わずに低速信号を取得することができるため、デコードに起因した誤りの伝搬を抑制することができる。
As described above, according to the present embodiment, the transmission apparatus 100 pre-codes the low-speed signal, and performs phase modulation of the optical signal phase-modulated according to the high-speed signal in accordance with the pre-coded low-speed signal. As a result, the receiving apparatus 200 can acquire a low-speed signal without decoding the low-speed signal, and thus can suppress the propagation of errors due to the decoding.
以上、図面を参照してこの発明の第2の実施形態について詳しく説明したが、具体的な構成は上述のものに限られることはなく、この発明の要旨を逸脱しない範囲内において様々な設計変更等をすることが可能である。
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 The second embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 The second embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
なお、本実施形態では、遅延干渉部202の遅延量が高速信号の1シンボル時間に相当する場合を説明したが、これに限られない。例えば遅延量を低速信号の1シンボル時間とすることで、低速信号検波部211に入力される電気信号の電圧が0となる時間を長くし、低速信号検波部211の識別の余裕を広げ、識別誤りの可能性を低下させても良い。
In the present embodiment, the case where the delay amount of the delay interference unit 202 corresponds to one symbol time of a high-speed signal has been described, but the present invention is not limited to this. For example, by setting the delay amount to one symbol time of the low-speed signal, the time during which the voltage of the electric signal input to the low-speed signal detection unit 211 becomes 0 is lengthened, and the identification margin of the low-speed signal detection unit 211 is widened. The possibility of error may be reduced.
(第3の実施形態)
次に、本発明の第3の実施形態について説明する。第3の実施形態は、送信装置100で高速信号の周波数を2分周したクロック信号と低速信号との論理積となる信号に応じ、高速信号に応じて位相変調した光信号の位相変調を行う光伝送システムの例である。これにより、受信装置200で低速信号のデコードを行わずに低速信号を取得する。 (Third embodiment)
Next, a third embodiment of the present invention will be described. The third embodiment performs phase modulation of an optical signal that is phase-modulated in accordance with a high-speed signal in accordance with a signal that is a logical product of a clock signal obtained by dividing the frequency of the high-speed signal by 2 and a low-speed signal. It is an example of an optical transmission system. As a result, the low-speed signal is acquired without decoding the low-speed signal by the receivingapparatus 200.
次に、本発明の第3の実施形態について説明する。第3の実施形態は、送信装置100で高速信号の周波数を2分周したクロック信号と低速信号との論理積となる信号に応じ、高速信号に応じて位相変調した光信号の位相変調を行う光伝送システムの例である。これにより、受信装置200で低速信号のデコードを行わずに低速信号を取得する。 (Third embodiment)
Next, a third embodiment of the present invention will be described. The third embodiment performs phase modulation of an optical signal that is phase-modulated in accordance with a high-speed signal in accordance with a signal that is a logical product of a clock signal obtained by dividing the frequency of the high-speed signal by 2 and a low-speed signal. It is an example of an optical transmission system. As a result, the low-speed signal is acquired without decoding the low-speed signal by the receiving
図7は、本発明の第3の実施形態に従った光伝送システムの構成を示す概略ブロック図である。
第3の実施形態に従った光伝送システムの構成は、第1の実施形態に加えて送信装置100にさらにクロック出力部121と論理積演算部122とを備え、受信装置200の低速信号デコード部205の代わりに低速信号検波部211を備える構成である。なお、その他の処理部は第1の実施形態の光伝送システムの構成と同じであるため、同一の符号を用いて説明する。クロック出力部121、論理積演算部122および低速信号位相変調部105は本発明の低速信号変調部に相当する。また、低速信号検波部211は本発明の低速信号取得部に相当する。また、位相変調部206および高速光受信部207は本発明の高速信号取得部に相当する。
本実施形態において、送信装置100のクロック出力部121は高速信号の周波数を2分周した周波数のクロック信号(すなわち、その周波数が高速信号のシンボルレートの半分であるクロック信号)を出力する。論理積演算部122は、低速信号出力部103が出力する低速信号とクロック出力部121が出力するクロック信号の論理積を出力する。すなわち、低速信号のビットが0の場合は出力が0となり、低速信号のビットが1の場合は高速信号の1シンボル時間を周期に光位相振幅がπ/2で切り替わる信号となる。論理積演算部122には、例えばAND回路を用いる。低速信号位相変調部105は論理積演算部122が出力する信号に応じて高速信号位相変調部104が位相変調した光信号の位相変調を行う。また、受信装置200の低速信号検波部211はデコード処理を行わずに、整流部204が全波整流した電気信号を検波して低速信号を取得する。 FIG. 7 is a schematic block diagram showing a configuration of an optical transmission system according to the third embodiment of the present invention.
The configuration of the optical transmission system according to the third embodiment includes aclock output unit 121 and an AND operation unit 122 in addition to the transmission device 100 in addition to the first embodiment, and a low-speed signal decoding unit of the reception device 200. Instead of 205, a low-speed signal detection unit 211 is provided. The other processing units are the same as those of the optical transmission system according to the first embodiment, and therefore will be described using the same reference numerals. The clock output unit 121, the AND operation unit 122, and the low-speed signal phase modulation unit 105 correspond to the low-speed signal modulation unit of the present invention. The low speed signal detection unit 211 corresponds to the low speed signal acquisition unit of the present invention. The phase modulation unit 206 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
In this embodiment, theclock output unit 121 of the transmission apparatus 100 outputs a clock signal having a frequency obtained by dividing the frequency of the high-speed signal by two (that is, a clock signal whose frequency is half the symbol rate of the high-speed signal). The logical product operation unit 122 outputs a logical product of the low-speed signal output from the low-speed signal output unit 103 and the clock signal output from the clock output unit 121. That is, when the bit of the low-speed signal is 0, the output is 0, and when the bit of the low-speed signal is 1, the optical phase amplitude is switched by π / 2 with one symbol time of the high-speed signal as a cycle. For the AND operation unit 122, for example, an AND circuit is used. The low-speed signal phase modulation unit 105 performs phase modulation of the optical signal phase-modulated by the high-speed signal phase modulation unit 104 in accordance with the signal output from the AND operation unit 122. Further, the low-speed signal detection unit 211 of the reception device 200 detects the electric signal that has been full-wave rectified by the rectification unit 204 without performing decoding processing, and acquires a low-speed signal.
第3の実施形態に従った光伝送システムの構成は、第1の実施形態に加えて送信装置100にさらにクロック出力部121と論理積演算部122とを備え、受信装置200の低速信号デコード部205の代わりに低速信号検波部211を備える構成である。なお、その他の処理部は第1の実施形態の光伝送システムの構成と同じであるため、同一の符号を用いて説明する。クロック出力部121、論理積演算部122および低速信号位相変調部105は本発明の低速信号変調部に相当する。また、低速信号検波部211は本発明の低速信号取得部に相当する。また、位相変調部206および高速光受信部207は本発明の高速信号取得部に相当する。
本実施形態において、送信装置100のクロック出力部121は高速信号の周波数を2分周した周波数のクロック信号(すなわち、その周波数が高速信号のシンボルレートの半分であるクロック信号)を出力する。論理積演算部122は、低速信号出力部103が出力する低速信号とクロック出力部121が出力するクロック信号の論理積を出力する。すなわち、低速信号のビットが0の場合は出力が0となり、低速信号のビットが1の場合は高速信号の1シンボル時間を周期に光位相振幅がπ/2で切り替わる信号となる。論理積演算部122には、例えばAND回路を用いる。低速信号位相変調部105は論理積演算部122が出力する信号に応じて高速信号位相変調部104が位相変調した光信号の位相変調を行う。また、受信装置200の低速信号検波部211はデコード処理を行わずに、整流部204が全波整流した電気信号を検波して低速信号を取得する。 FIG. 7 is a schematic block diagram showing a configuration of an optical transmission system according to the third embodiment of the present invention.
The configuration of the optical transmission system according to the third embodiment includes a
In this embodiment, the
以下に、具体的な信号の例を用いて光伝送システムの説明を行う。
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。
図8は、第3の実施形態における各処理部が出力する信号の波形を示す図である。なお、ここでは低速信号のビットが1,0,0,0,1,1,0,1,1,1と順次変化する場合についての例を示してある。
図8(a)は、高速信号位相変調部104が出力する光信号の位相の遷移を示す。
図8(a)の縦軸は位相を示し、横軸は時間を示す。高速信号位相変調部104が出力する光信号の位相は0とπとを遷移する。
図8(b)は、低速信号位相変調部105が出力する光信号の位相の遷移を示す。
図8(b)の縦軸は位相を示し、横軸は時間を示す。低速信号位相変調部105が出力する光信号の位相は0、π/2、π、3π/2を遷移する。このとき、低速信号のビットが0となる期間では位相が0またはπとなる。また、低速信号のビットが1となる期間では、位相がπ/2または3π/2となる信号と、位相が0またはπとなる信号とが25p(=1/40G)s(pico second:ピコ秒)毎に切り替わる。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speedsignal output unit 102 outputs a high-speed signal of 40 Gbps and the low-speed signal output unit 103 outputs a low-speed signal of 10 Gbps will be described.
FIG. 8 is a diagram illustrating a waveform of a signal output from each processing unit according to the third embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
FIG. 8A shows the phase transition of the optical signal output from the high-speed signalphase modulation unit 104.
In FIG. 8A, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the high-speed signalphase modulation unit 104 transitions between 0 and π.
FIG. 8B shows the phase transition of the optical signal output from the low-speedsignal phase modulator 105.
In FIG. 8B, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the low-speedsignal phase modulator 105 transitions between 0, π / 2, π, and 3π / 2. At this time, the phase is 0 or π during the period when the bit of the low-speed signal is 0. In the period when the bit of the low-speed signal is 1, the signal whose phase is π / 2 or 3π / 2 and the signal whose phase is 0 or π are 25p (= 1 / 40G) s (pico second: pico second: Every second).
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。
図8は、第3の実施形態における各処理部が出力する信号の波形を示す図である。なお、ここでは低速信号のビットが1,0,0,0,1,1,0,1,1,1と順次変化する場合についての例を示してある。
図8(a)は、高速信号位相変調部104が出力する光信号の位相の遷移を示す。
図8(a)の縦軸は位相を示し、横軸は時間を示す。高速信号位相変調部104が出力する光信号の位相は0とπとを遷移する。
図8(b)は、低速信号位相変調部105が出力する光信号の位相の遷移を示す。
図8(b)の縦軸は位相を示し、横軸は時間を示す。低速信号位相変調部105が出力する光信号の位相は0、π/2、π、3π/2を遷移する。このとき、低速信号のビットが0となる期間では位相が0またはπとなる。また、低速信号のビットが1となる期間では、位相がπ/2または3π/2となる信号と、位相が0またはπとなる信号とが25p(=1/40G)s(pico second:ピコ秒)毎に切り替わる。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speed
FIG. 8 is a diagram illustrating a waveform of a signal output from each processing unit according to the third embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
FIG. 8A shows the phase transition of the optical signal output from the high-speed signal
In FIG. 8A, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the high-speed signal
FIG. 8B shows the phase transition of the optical signal output from the low-speed
In FIG. 8B, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the low-speed
図8(c)は、光検出部203が出力する電気信号の電圧の遷移を示す。
図8(c)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した一方の光信号すなわち低速信号位相変調部105が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、光検出部203の出力信号は、低速信号位相変調部105が出力する光信号の隣接するシンボル間の位相差に応じて電圧がV、または、-Vとなる。また、低速信号のビットが1の場合に電圧は0となる。その理由は、低速信号のビットが1となる期間では、低速信号位相変調部105から出力される光信号は、位相がπ/2または3π/2となる信号と、位相が0またはπとなる信号とが25ps毎に切り替わるため、低速信号のビットが1となる期間ではシンボル間の位相差は常にπ/2または3π/2となることによるものである。
図8(d)は、整流部204が出力する電気信号の電圧の遷移を示す。
図8(d)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、低速信号のビットが1の場合に電圧が0となり、低速信号のビットが0の場合に電圧がVとなる。 FIG. 8C shows the transition of the voltage of the electric signal output from thelight detection unit 203.
In FIG. 8C, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from thelight detection unit 203 transitions between V, 0, and −V. The electrical signal output from the light detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal. The delay interference unit 202 performs delay interference of one optical signal branched by the optical branching unit 201, that is, the optical signal output from the low-speed signal phase modulation unit 105. At this time, when the phase difference between adjacent symbols is 0, the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201. When the phase difference between adjacent symbols is π, the intensity of the optical signal output from the delay interference unit 202 is zero. When the phase difference between adjacent symbols is π / 2 or 3π / 2, the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to −V when the intensity of the input optical signal is 0. Therefore, the output signal of the light detection unit 203 has a voltage of V or −V according to the phase difference between adjacent symbols of the optical signal output from the low-speed signal phase modulation unit 105. When the bit of the low speed signal is 1, the voltage is 0. The reason is that during the period when the bit of the low-speed signal is 1, the optical signal output from the low-speed signal phase modulation unit 105 is 0 or π in phase with the signal having a phase of π / 2 or 3π / 2. This is because the phase difference between symbols is always π / 2 or 3π / 2 during the period when the bit of the low-speed signal is 1, since the signal is switched every 25 ps.
FIG. 8D shows the transition of the voltage of the electric signal output from the rectifyingunit 204.
In FIG. 8D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifyingunit 204 transitions between V and 0. The rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Therefore, the voltage is 0 when the bit of the low-speed signal is 1, and the voltage is V when the bit of the low-speed signal is 0.
図8(c)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した一方の光信号すなわち低速信号位相変調部105が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、光検出部203の出力信号は、低速信号位相変調部105が出力する光信号の隣接するシンボル間の位相差に応じて電圧がV、または、-Vとなる。また、低速信号のビットが1の場合に電圧は0となる。その理由は、低速信号のビットが1となる期間では、低速信号位相変調部105から出力される光信号は、位相がπ/2または3π/2となる信号と、位相が0またはπとなる信号とが25ps毎に切り替わるため、低速信号のビットが1となる期間ではシンボル間の位相差は常にπ/2または3π/2となることによるものである。
図8(d)は、整流部204が出力する電気信号の電圧の遷移を示す。
図8(d)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、低速信号のビットが1の場合に電圧が0となり、低速信号のビットが0の場合に電圧がVとなる。 FIG. 8C shows the transition of the voltage of the electric signal output from the
In FIG. 8C, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the
FIG. 8D shows the transition of the voltage of the electric signal output from the rectifying
In FIG. 8D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifying
そのため、低速信号検波部211は整流部204が出力する電気信号の電圧が0の場合に1を出力し、電圧がVの場合に0を出力することで、低速信号を取得することができる。なお、整流部204が出力する電気信号には、高速信号のビット変化に伴う高速の波形変動の影響がノイズとなって現れる。これにより低速信号検波部211がノイズを誤って認識してしまう可能性がある。そのため、整流部204が出力する電気信号の帯域を例えばローパスフィルタで低速信号レベルの帯域に制限することでノイズを除去するとよい。
Therefore, the low-speed signal detector 211 can acquire a low-speed signal by outputting 1 when the voltage of the electrical signal output from the rectifier 204 is 0 and outputting 0 when the voltage is V. It should be noted that the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise. As a result, there is a possibility that the low-speed signal detection unit 211 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
このように、本実施形態によれば、送信装置100で高速信号の周波数を2分周したクロック信号と低速信号との論理積となる信号に応じ、高速信号に応じて位相変調した光信号の位相変調を行う。これにより、受信装置200は低速信号のデコードを行わずに低速信号を取得することができるため、デコードに起因した誤りの伝搬を抑制することができる。
As described above, according to the present embodiment, in accordance with the signal that is the logical product of the clock signal obtained by dividing the frequency of the high-speed signal by 2 and the low-speed signal in the transmission apparatus 100, Perform phase modulation. As a result, the receiving apparatus 200 can acquire a low-speed signal without decoding the low-speed signal, and thus can suppress the propagation of errors due to the decoding.
以上、図面を参照してこの発明の第3の実施形態について詳しく説明したが、具体的な構成は上述のものに限られることはなく、この発明の要旨を逸脱しない範囲内において様々な設計変更等をすることが可能である。
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 Although the third embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 Although the third embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
(第4の実施形態)
次に、本発明の第4の実施形態について説明する。第4の実施形態は、送信装置100で低速信号に応じ、高速信号に応じて位相変調した光信号の周波数変調を行い、受信装置200で低速信号のデコードを行わずに低速信号を取得する光伝送システムの例である。 (Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, thetransmitter 100 performs frequency modulation of an optical signal phase-modulated according to a high-speed signal in response to a low-speed signal, and the receiver 200 acquires the low-speed signal without decoding the low-speed signal. It is an example of a transmission system.
次に、本発明の第4の実施形態について説明する。第4の実施形態は、送信装置100で低速信号に応じ、高速信号に応じて位相変調した光信号の周波数変調を行い、受信装置200で低速信号のデコードを行わずに低速信号を取得する光伝送システムの例である。 (Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the
図9は、本発明の第4の実施形態に従った光伝送システムの構成を示す概略ブロック図である。
第4の実施形態に従った光伝送システムの構成は、第1の実施形態の送信装置100の低速信号位相変調部105の代わりに周波数変調部131を備え、受信装置200の低速信号デコード部205の代わりに低速信号検波部211を備え、受信装置200の位相変調部206の代わりに周波数変調部231を備える構成である。なお、その他の処理部は第1の実施形態の光伝送システムの構成と同じであるため、同一の符号を用いて説明する。周波数変調部131は本発明の低速信号変調部に相当する。また、低速信号検波部211は本発明の低速信号取得部に相当する。また、周波数変調部231および高速光受信部207は本発明の高速信号取得部に相当する。 FIG. 9 is a schematic block diagram showing a configuration of an optical transmission system according to the fourth embodiment of the present invention.
The configuration of the optical transmission system according to the fourth embodiment includes afrequency modulation unit 131 instead of the low-speed signal phase modulation unit 105 of the transmission device 100 of the first embodiment, and the low-speed signal decoding unit 205 of the reception device 200. In this configuration, a low-speed signal detection unit 211 is provided instead of the frequency modulation unit 231, and a frequency modulation unit 231 is provided instead of the phase modulation unit 206 of the reception device 200. The other processing units are the same as those of the optical transmission system according to the first embodiment, and therefore will be described using the same reference numerals. The frequency modulation unit 131 corresponds to the low-speed signal modulation unit of the present invention. The low speed signal detection unit 211 corresponds to the low speed signal acquisition unit of the present invention. Further, the frequency modulation unit 231 and the high-speed optical reception unit 207 correspond to a high-speed signal acquisition unit of the present invention.
第4の実施形態に従った光伝送システムの構成は、第1の実施形態の送信装置100の低速信号位相変調部105の代わりに周波数変調部131を備え、受信装置200の低速信号デコード部205の代わりに低速信号検波部211を備え、受信装置200の位相変調部206の代わりに周波数変調部231を備える構成である。なお、その他の処理部は第1の実施形態の光伝送システムの構成と同じであるため、同一の符号を用いて説明する。周波数変調部131は本発明の低速信号変調部に相当する。また、低速信号検波部211は本発明の低速信号取得部に相当する。また、周波数変調部231および高速光受信部207は本発明の高速信号取得部に相当する。 FIG. 9 is a schematic block diagram showing a configuration of an optical transmission system according to the fourth embodiment of the present invention.
The configuration of the optical transmission system according to the fourth embodiment includes a
本実施形態において、送信装置100の周波数変調部131は、低速信号出力部103が出力する低速信号に応じて、高速信号位相変調部104が位相変調した光信号の周波数変調を行う。また、周波数変調部131は、遅延干渉部202の遅延量の逆数の1/4に相当する周波数を周波数シフト量とする。例えば、遅延干渉部202の遅延量が25ps(pico second:ピコ秒)である場合、1/(25×10-12)×1/4=1010となるため、周波数シフト量は、10Gbpsとする。
受信装置200の低速信号検波部211はデコード処理を行わずに、整流部204が全波整流した電気信号を検波して低速信号を取得する。
受信装置200の周波数変調部231は、低速信号検波部211が出力した信号に応じて、光分岐部201が分岐した他方の光信号の周波数変調を行う。周波数変調部231も周波数変調部131と同様に、遅延干渉部202の遅延量の逆数の1/4に相当する周波数を周波数シフト量とする。 In the present embodiment, thefrequency modulation unit 131 of the transmission apparatus 100 performs frequency modulation of the optical signal phase-modulated by the high-speed signal phase modulation unit 104 according to the low-speed signal output from the low-speed signal output unit 103. Further, the frequency modulation unit 131 sets a frequency corresponding to ¼ of the reciprocal of the delay amount of the delay interference unit 202 as the frequency shift amount. For example, when the delay amount of the delay interference unit 202 is 25 ps (pico second), 1 / (25 × 10 −12 ) × 1/4 = 10 10 , so the frequency shift amount is 10 Gbps. .
The low-speedsignal detection unit 211 of the reception device 200 detects the electric signal that has been full-wave rectified by the rectification unit 204 without performing a decoding process, and acquires a low-speed signal.
Thefrequency modulation unit 231 of the reception device 200 performs frequency modulation of the other optical signal branched by the optical branching unit 201 in accordance with the signal output from the low-speed signal detection unit 211. Similarly to the frequency modulation unit 131, the frequency modulation unit 231 uses a frequency corresponding to ¼ of the reciprocal of the delay amount of the delay interference unit 202 as the frequency shift amount.
受信装置200の低速信号検波部211はデコード処理を行わずに、整流部204が全波整流した電気信号を検波して低速信号を取得する。
受信装置200の周波数変調部231は、低速信号検波部211が出力した信号に応じて、光分岐部201が分岐した他方の光信号の周波数変調を行う。周波数変調部231も周波数変調部131と同様に、遅延干渉部202の遅延量の逆数の1/4に相当する周波数を周波数シフト量とする。 In the present embodiment, the
The low-speed
The
以下に、具体的な信号の例を用いて光伝送システムの説明を行う。
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。したがって、遅延干渉部202の遅延量は25psとなり、周波数変調部131、231の周波数シフト量は10Gbpsとなる。
図10は、第4の実施形態における各処理部が出力する信号の波形を示す図である。なお、ここでは低速信号のビットが1,0,0,0,1,1,0,1,1,1と順次変化する場合についての例を示してある。
図10(a)は、低速信号出力部103が出力する信号のビットの遷移を示す。
図10(a)の縦軸はビットを示し、横軸は時間を示す。低速信号出力部103が出力する信号は0と1とを遷移する。
図10(b)は、周波数変調部131が出力する光信号の位相の遷移を示す。
図10(b)の縦軸は位相を示し、横軸は時間を示す。周波数変調部131が出力する光信号は、低速信号のビットが0となる期間で位相が0またはπとなり、低速信号のビットが1となる期間で25psあたりに位相がπ/2だけ遷移し続ける。これは、周波数シフト量10Gbpsで周波数変調を行っているために、25psで位相がπ/2回転するためである。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speedsignal output unit 102 outputs a high-speed signal of 40 Gbps and the low-speed signal output unit 103 outputs a low-speed signal of 10 Gbps will be described. Therefore, the delay amount of the delay interference unit 202 is 25 ps, and the frequency shift amount of the frequency modulation units 131 and 231 is 10 Gbps.
FIG. 10 is a diagram illustrating a waveform of a signal output from each processing unit according to the fourth embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
FIG. 10A shows bit transition of the signal output from the low-speedsignal output unit 103.
In FIG. 10A, the vertical axis represents bits and the horizontal axis represents time. The signal output from the low-speedsignal output unit 103 transitions between 0 and 1.
FIG. 10B shows the phase transition of the optical signal output from thefrequency modulation unit 131.
In FIG. 10B, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from thefrequency modulation unit 131 is 0 or π during the period when the bit of the low-speed signal is 0, and the phase continues to shift by π / 2 per 25 ps during the period when the bit of the low-speed signal is 1. . This is because the phase is rotated by π / 2 at 25 ps because frequency modulation is performed with a frequency shift amount of 10 Gbps.
ここで、高速信号出力部102が40Gbpsの高速信号を出力し、低速信号出力部103が10Gbpsの低速信号を出力した場合の例を用いて説明する。したがって、遅延干渉部202の遅延量は25psとなり、周波数変調部131、231の周波数シフト量は10Gbpsとなる。
図10は、第4の実施形態における各処理部が出力する信号の波形を示す図である。なお、ここでは低速信号のビットが1,0,0,0,1,1,0,1,1,1と順次変化する場合についての例を示してある。
図10(a)は、低速信号出力部103が出力する信号のビットの遷移を示す。
図10(a)の縦軸はビットを示し、横軸は時間を示す。低速信号出力部103が出力する信号は0と1とを遷移する。
図10(b)は、周波数変調部131が出力する光信号の位相の遷移を示す。
図10(b)の縦軸は位相を示し、横軸は時間を示す。周波数変調部131が出力する光信号は、低速信号のビットが0となる期間で位相が0またはπとなり、低速信号のビットが1となる期間で25psあたりに位相がπ/2だけ遷移し続ける。これは、周波数シフト量10Gbpsで周波数変調を行っているために、25psで位相がπ/2回転するためである。 The optical transmission system will be described below using specific signal examples.
Here, an example in which the high-speed
FIG. 10 is a diagram illustrating a waveform of a signal output from each processing unit according to the fourth embodiment. Here, an example is shown in which the bits of the low-speed signal are sequentially changed to 1, 0, 0, 0, 1, 1, 0, 1, 1, 1.
FIG. 10A shows bit transition of the signal output from the low-speed
In FIG. 10A, the vertical axis represents bits and the horizontal axis represents time. The signal output from the low-speed
FIG. 10B shows the phase transition of the optical signal output from the
In FIG. 10B, the vertical axis indicates the phase, and the horizontal axis indicates time. The phase of the optical signal output from the
図10(c)は、光検出部203が出力する電気信号の電圧の遷移を示す。
図10(c)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。このとき、低速信号のビットが1の場合に電圧が0となり、低速信号のビットが0の場合に電圧がVまたは-Vとなる。また、低速信号のビットの切り替わり点の直後の25psは、電圧が0からVもしくは-Vに、またはVもしくは-Vから0に滑らかに遷移する。
光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した光信号すなわち周波数変調部131が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、遅延干渉部202から出力される電圧は、周波数変調部131が出力する光信号の隣接するシンボル間の位相差に応じて電圧がV、または、-Vとなり、低速信号のビットが1の場合に電圧は0となる。その理由は、低速信号のビットが1となる期間では、周波数変調部131が出力する光信号はその位相が25psあたりにπ/2だけ遷移し続けるため、低速信号のビットが1となる期間では隣接するシンボル間の位相差は常にπ/2または3π/2となるためである。
図10(d)は、整流部204が出力する電気信号の電圧の遷移を示す。
図10(d)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、低速信号のビットが1の場合に電圧が0となり、低速信号のビットが0の場合に電圧がVとなる。 FIG. 10C shows the transition of the voltage of the electric signal output from thelight detection unit 203.
In FIG. 10C, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from thelight detection unit 203 transitions between V, 0, and −V. At this time, when the bit of the low-speed signal is 1, the voltage is 0, and when the bit of the low-speed signal is 0, the voltage is V or -V. Also, at 25 ps immediately after the bit switching point of the low-speed signal, the voltage smoothly transitions from 0 to V or −V, or from V or −V to 0.
The electrical signal output from thelight detection unit 203 is obtained by converting the optical signal output from the delay interference unit 202 into an electrical signal. The delay interference unit 202 performs delay interference of the optical signal branched by the optical branching unit 201, that is, the optical signal output from the frequency modulation unit 131. At this time, when the phase difference between adjacent symbols is 0, the intensity of the optical signal output from the delay interference unit 202 is twice the intensity of the optical signal branched by the optical branching unit 201. When the phase difference between adjacent symbols is π, the intensity of the optical signal output from the delay interference unit 202 is zero. When the phase difference between adjacent symbols is π / 2 or 3π / 2, the intensity of the optical signal output from the delay interference unit 202 is the same as the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to V when the intensity of the input optical signal is twice the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to 0 when the intensity of the input optical signal is equal to the intensity of the optical signal branched by the optical branching unit 201. The light detection unit 203 sets the voltage of the output signal to −V when the intensity of the input optical signal is 0. Therefore, the voltage output from the delay interference unit 202 is V or −V depending on the phase difference between adjacent symbols of the optical signal output from the frequency modulation unit 131, and the bit of the low-speed signal is 1. In this case, the voltage becomes zero. The reason is that in the period when the bit of the low-speed signal is 1, the phase of the optical signal output from the frequency modulator 131 continues to transition by π / 2 per 25 ps. This is because the phase difference between adjacent symbols is always π / 2 or 3π / 2.
FIG. 10D shows the transition of the voltage of the electric signal output from the rectifyingunit 204.
In FIG. 10D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifyingunit 204 transitions between V and 0. The rectification unit 204 outputs an electrical signal that is an absolute value of the electrical signal output by the light detection unit 203. Therefore, the voltage is 0 when the bit of the low-speed signal is 1, and the voltage is V when the bit of the low-speed signal is 0.
図10(c)の縦軸は電圧を示し、横軸は時間を示す。光検出部203が出力する電気信号はV、0、-Vを遷移する。このとき、低速信号のビットが1の場合に電圧が0となり、低速信号のビットが0の場合に電圧がVまたは-Vとなる。また、低速信号のビットの切り替わり点の直後の25psは、電圧が0からVもしくは-Vに、またはVもしくは-Vから0に滑らかに遷移する。
光検出部203が出力する電気信号は、遅延干渉部202が出力する光信号を電気信号に変換したものである。遅延干渉部202は、光分岐部201が分岐した光信号すなわち周波数変調部131が出力する光信号の遅延干渉を行う。このとき、隣接するシンボル間の位相差が0の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度の2倍になる。また、隣接するシンボル間の位相差がπの場合、遅延干渉部202が出力する光信号の強度は0になる。隣接するシンボル間の位相差がπ/2または3π/2の場合、遅延干渉部202が出力する光信号の強度は光分岐部201が分岐した光信号の強度と同じになる。光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度の2倍のとき、出力信号の電圧をVとする。また、光検出部203は、入力された光信号の強度が、光分岐部201が分岐した光信号の強度と等しいとき、出力信号の電圧を0とする。また、光検出部203は、入力された光信号の強度が0のとき、出力信号の電圧を-Vとする。したがって、遅延干渉部202から出力される電圧は、周波数変調部131が出力する光信号の隣接するシンボル間の位相差に応じて電圧がV、または、-Vとなり、低速信号のビットが1の場合に電圧は0となる。その理由は、低速信号のビットが1となる期間では、周波数変調部131が出力する光信号はその位相が25psあたりにπ/2だけ遷移し続けるため、低速信号のビットが1となる期間では隣接するシンボル間の位相差は常にπ/2または3π/2となるためである。
図10(d)は、整流部204が出力する電気信号の電圧の遷移を示す。
図10(d)の縦軸は電圧を示し、横軸は時間を示す。整流部204が出力する電気信号はVと0とを遷移する。整流部204は、光検出部203が出力する電気信号の絶対値となる電気信号を出力する。したがって、低速信号のビットが1の場合に電圧が0となり、低速信号のビットが0の場合に電圧がVとなる。 FIG. 10C shows the transition of the voltage of the electric signal output from the
In FIG. 10C, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the
The electrical signal output from the
FIG. 10D shows the transition of the voltage of the electric signal output from the rectifying
In FIG. 10D, the vertical axis represents voltage, and the horizontal axis represents time. The electrical signal output from the rectifying
そのため、低速信号検波部211は整流部204が出力する電気信号の電圧が0の場合に1を出力し、電圧がVの場合に0を出力することで、低速信号を取得することができる。ただし、整流部204が出力する電気信号は、電圧の立ち上がりと立ち下がりが滑らかになっているため、低速信号検波部211は電圧の立ち上がりまたは立ち下がりが安定したタイミングで検波を行う必要がある。なお、整流部204が出力する電気信号には、高速信号のビット変化に伴う高速の波形変動の影響がノイズとなって現れる。これにより低速信号検波部211がノイズを誤って認識してしまう可能性がある。そのため、整流部204が出力する電気信号の帯域を例えばローパスフィルタで低速信号レベルの帯域に制限することでノイズを除去するとよい。
Therefore, the low-speed signal detection unit 211 can obtain a low-speed signal by outputting 1 when the voltage of the electrical signal output from the rectification unit 204 is 0 and outputting 0 when the voltage is V. However, since the electrical signal output from the rectifying unit 204 has a smooth rise and fall of the voltage, the low-speed signal detection unit 211 needs to detect at a timing when the rise or fall of the voltage is stable. It should be noted that the electrical signal output from the rectifying unit 204 is affected by high-speed waveform fluctuations caused by bit changes of the high-speed signal as noise. As a result, there is a possibility that the low-speed signal detection unit 211 may erroneously recognize noise. Therefore, noise may be removed by limiting the band of the electrical signal output from the rectifying unit 204 to a band of a low-speed signal level using, for example, a low-pass filter.
このように、本実施形態によれば、送信装置100で低速信号に応じて、高速信号に応じて位相変調した光信号の周波数変調を行う。これにより、受信装置200は低速信号のデコードを行わずに低速信号を取得することができるため、デコードに起因した誤りの伝搬を抑制することができる。
As described above, according to the present embodiment, the transmission apparatus 100 performs frequency modulation of the optical signal phase-modulated according to the high-speed signal according to the low-speed signal. As a result, the receiving apparatus 200 can acquire a low-speed signal without decoding the low-speed signal, and thus can suppress the propagation of errors due to the decoding.
以上、図面を参照してこの発明の第4の実施形態について詳しく説明したが、具体的な構成は上述のものに限られることはなく、この発明の要旨を逸脱しない範囲内において様々な設計変更等をすることが可能である。
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 Although the fourth embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
例えば、本実施形態では高速信号が40Gbps、低速信号が10Gbpsである場合を説明した。しかし、これら2つの信号は必ずしも周波数逓倍の関係で同期している必要はなく、低速信号の切り替わりが検出でき、信号が再生できれば良いため、周波数逓倍でなくても良く、また非同期であっても良い。 Although the fourth embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
For example, in the present embodiment, the case where the high-speed signal is 40 Gbps and the low-speed signal is 10 Gbps has been described. However, these two signals do not necessarily have to be synchronized due to frequency multiplication, and it is only necessary to be able to detect switching of a low-speed signal and to reproduce the signal. good.
なお、本実施形態では、遅延干渉部202の遅延量が高速信号の1シンボル時間に相当する場合を説明したが、これに限られない。例えば遅延量を低速信号の1シンボル時間とし、周波数変調部131の周波数シフト量を2.5GHzとすることで、送信部106から送信される光信号のスペクトル広がりを小さくしてもよい。
In the present embodiment, the case where the delay amount of the delay interference unit 202 corresponds to one symbol time of a high-speed signal has been described, but the present invention is not limited to this. For example, the spectral spread of the optical signal transmitted from the transmission unit 106 may be reduced by setting the delay amount to one symbol time of the low-speed signal and the frequency shift amount of the frequency modulation unit 131 to 2.5 GHz.
また、本実施形態では、受信装置200に周波数変調部231を備え、低速信号成分を除去して高速信号を取り出す場合を説明したが、これに限られない。例えば、周波数変調部131で与える周波数シフト量が小さく、高速信号の復調において周波数変調部231を用いて低速信号成分を除去せずに高速信号をデコードすることができる場合、周波数変調部231を備えず、光分岐部201が分岐した光信号を直接高速光受信部207でデコードすることで、受信装置200の構造を簡易化してもよい。
In the present embodiment, the case has been described in which the receiving apparatus 200 includes the frequency modulation unit 231 and removes the low-speed signal component to extract the high-speed signal. However, the present invention is not limited to this. For example, when the frequency shift amount given by the frequency modulation unit 131 is small and the high-speed signal can be decoded without removing the low-speed signal component using the frequency modulation unit 231 in the demodulation of the high-speed signal, the frequency modulation unit 231 is provided. Instead, the structure of the receiving apparatus 200 may be simplified by directly decoding the optical signal branched by the optical branching unit 201 by the high-speed optical receiving unit 207.
(第5の実施形態)
次に、本発明の第5の実施形態について説明する。第5の実施形態は、第1の実施形態から第4の実施形態において、整流部204として高速の全波整流回路を用いる場合、オペアンプなどの集積回路で生じる時間遅れに起因して、信号の周波数が高い場合に波形歪みが生じてしまうという問題を解決するものである。 (Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, when a high-speed full-wave rectifier circuit is used as therectifier 204 in the first to fourth embodiments, a signal delay occurs due to a time delay generated in an integrated circuit such as an operational amplifier. This solves the problem of waveform distortion occurring when the frequency is high.
次に、本発明の第5の実施形態について説明する。第5の実施形態は、第1の実施形態から第4の実施形態において、整流部204として高速の全波整流回路を用いる場合、オペアンプなどの集積回路で生じる時間遅れに起因して、信号の周波数が高い場合に波形歪みが生じてしまうという問題を解決するものである。 (Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, when a high-speed full-wave rectifier circuit is used as the
図11は、第5の実施形態に従った整流部の構成を示す概略ブロック図である。
整流部204は、光源部241と、マッハツェンダ変調部242と、光検出部243とを備える。
光源部241は、CW光を出力する。
マッハツェンダ変調部242は、光検出部203が出力する電気信号に基づいてCW光の強度を変調する。マッハツェンダ変調部242は、予め光検出部203が出力する電気信号の電圧が0のときに出力する光信号の強度が0となるようバイアス電圧を調整する。これにより、光検出部203が出力する電気信号の電圧が0のときに、マッハツェンダ変調部242の出力する光信号の強度が0となり、光検出部203が出力する電気信号の電圧がVまたは-Vのときに、マッハツェンダ変調部242の出力する光信号の強度が最大となる。
光検出部243は、マッハツェンダ変調部242が出力する光信号を電気信号に変換する。光検出部243は、光信号の強度が0のときに出力する電気信号の電圧を0とし、光信号の強度が最大のときに出力する電気信号の電圧をVとする。 FIG. 11 is a schematic block diagram showing the configuration of the rectifying unit according to the fifth embodiment.
Therectification unit 204 includes a light source unit 241, a Mach-Zehnder modulation unit 242, and a light detection unit 243.
Thelight source unit 241 outputs CW light.
The Mach-Zehnder modulation unit 242 modulates the intensity of the CW light based on the electric signal output from the light detection unit 203. The Mach-Zehnder modulation unit 242 previously adjusts the bias voltage so that the intensity of the optical signal output when the voltage of the electrical signal output by the light detection unit 203 is 0 is 0. Thus, when the voltage of the electrical signal output from the light detection unit 203 is 0, the intensity of the optical signal output from the Mach-Zehnder modulation unit 242 becomes 0, and the voltage of the electrical signal output from the light detection unit 203 is V or − At V, the intensity of the optical signal output from the Mach-Zehnder modulator 242 is maximized.
Thelight detection unit 243 converts the optical signal output from the Mach-Zehnder modulation unit 242 into an electrical signal. The light detection unit 243 sets the voltage of the electrical signal output when the intensity of the optical signal is 0 to 0, and sets the voltage of the electrical signal output when the intensity of the optical signal is maximum to V.
整流部204は、光源部241と、マッハツェンダ変調部242と、光検出部243とを備える。
光源部241は、CW光を出力する。
マッハツェンダ変調部242は、光検出部203が出力する電気信号に基づいてCW光の強度を変調する。マッハツェンダ変調部242は、予め光検出部203が出力する電気信号の電圧が0のときに出力する光信号の強度が0となるようバイアス電圧を調整する。これにより、光検出部203が出力する電気信号の電圧が0のときに、マッハツェンダ変調部242の出力する光信号の強度が0となり、光検出部203が出力する電気信号の電圧がVまたは-Vのときに、マッハツェンダ変調部242の出力する光信号の強度が最大となる。
光検出部243は、マッハツェンダ変調部242が出力する光信号を電気信号に変換する。光検出部243は、光信号の強度が0のときに出力する電気信号の電圧を0とし、光信号の強度が最大のときに出力する電気信号の電圧をVとする。 FIG. 11 is a schematic block diagram showing the configuration of the rectifying unit according to the fifth embodiment.
The
The
The Mach-
The
このように、本実施形態によれば、整流部204は、全波整流回路と同等の電気信号を出力することができる。本実施形態に従った整流部204は、オペアンプなどの集積回路を用いず、またマッハツェンダ変調部242は、高速な動作をさせることが容易であることから、歪みの少ない全波整流波形を得ることができる。
Thus, according to the present embodiment, the rectifying unit 204 can output an electrical signal equivalent to the full-wave rectifying circuit. The rectifying unit 204 according to the present embodiment does not use an integrated circuit such as an operational amplifier, and the Mach-Zehnder modulating unit 242 can easily operate at high speed, and thus can obtain a full-wave rectified waveform with less distortion. Can do.
以上、図面を参照してこの発明の第5の実施形態について詳しく説明したが、具体的な構成は上述のものに限られることはなく、この発明の要旨を逸脱しない範囲内において様々な設計変更等をすることが可能である。
The fifth embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to the above-described one, and various design changes can be made without departing from the scope of the present invention. Etc. are possible.
また、実施形態を参照して本発明を説明したが、本発明は上述した実施形態に限定されるものではない。本発明の構成や詳細には、本発明の範囲内で当業者が理解し得る様々な変更を加えることができる。
Further, although the present invention has been described with reference to the embodiments, the present invention is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.
この出願は、2008年9月5日に出願された日本出願特願2008-228061号を基礎とする優先権を主張し、その開示の全てをここに取り込む。
This application claims priority based on Japanese Patent Application No. 2008-228061 filed on September 5, 2008, the entire disclosure of which is incorporated herein.
本発明によれば、第1の信号とこの第1の信号よりも低速な第2の信号との多重信号を単峰性のスペクトルとすることができ、複数の信号を単一の波長スロット内に収めることができる。また、本発明によれば、既存の光伝送システムに必要部位を追加することで簡単に実装することができる。さらに、本発明によれば、第1の信号に応じた位相変調信号の長距離伝送特性を大きく失うことなく第2の信号を多重することができる。
According to the present invention, a multiplexed signal of a first signal and a second signal that is slower than the first signal can be made a unimodal spectrum, and a plurality of signals can be placed in a single wavelength slot. Can fit in. In addition, according to the present invention, it is possible to easily implement by adding a necessary part to an existing optical transmission system. Furthermore, according to the present invention, it is possible to multiplex the second signal without greatly losing the long-distance transmission characteristics of the phase modulation signal corresponding to the first signal.
100…送信装置 101…光源部 102…高速信号出力部 103…低速信号出力部 104…高速信号位相変調部 105…低速信号位相変調部 106…送信部 200…受信装置 201…光分岐部 202…遅延干渉部 203…光検出部 204…整流部 205…低速信号デコード部 206…位相変調部 207…高速光受信部
DESCRIPTION OF SYMBOLS 100 ... Transmission apparatus 101 ... Light source part 102 ... High speed signal output part 103 ... Low speed signal output part 104 ... High speed signal phase modulation part 105 ... Low speed signal phase modulation part 106 ... Transmission part 200 ... Reception apparatus 201 ... Optical branching part 202 ... Delay Interference unit 203 ... optical detection unit 204 ... rectification unit 205 ... low-speed signal decoding unit 206 ... phase modulation unit 207 ... high-speed optical reception unit
Claims (19)
- 速度が異なる2つの信号を1つの光信号に多重して送信する送信装置であって、
第1の信号を出力する高速信号出力部と、
前記第1の信号に応じて、位相シフト量をπとした位相変調を行う高速信号位相変調部と、
前記第1の信号よりも低速な第2の信号を出力する低速信号出力部と、
前記第2の信号に基づいて、前記高速信号位相変調部が出力した光信号の位相変調または周波数変調を行う低速信号変調部と、
前記低速信号変調部が出力した光信号を受信装置に送信する送信部と
を備えた送信装置。 A transmission device that multiplexes and transmits two signals having different speeds into one optical signal,
A high-speed signal output unit for outputting a first signal;
A high-speed signal phase modulation unit that performs phase modulation with a phase shift amount of π in accordance with the first signal;
A low-speed signal output unit that outputs a second signal that is slower than the first signal;
A low-speed signal modulator that performs phase modulation or frequency modulation of the optical signal output from the high-speed signal phase modulator based on the second signal;
A transmission device comprising: a transmission unit that transmits an optical signal output from the low-speed signal modulation unit to a reception device. - 速度が異なる2つの信号を多重した1つの光信号を受信する受信装置であって、
第1の信号に応じて位相シフト量をπとした位相変調を行ってから前記第1の信号よりも低速な第2の信号に基づいて位相変調または周波数変調を行った光信号を送信装置から取得して分岐する光分岐部と、
前記分岐した一方の光信号の遅延干渉を行い、干渉光を出力する遅延干渉部と、
前記干渉光を電気信号に変換する光検出部と、
前記電気信号を全波整流する整流部と、
前記全波整流した電気信号に基づいて前記第2の信号を取得する低速信号取得部と、
前記分岐した他方の光信号に基づいて前記第1の信号を取得する高速信号取得部と
を備える受信装置。 A receiving device for receiving one optical signal obtained by multiplexing two signals having different speeds,
An optical signal obtained by performing phase modulation with a phase shift amount π according to the first signal and then performing phase modulation or frequency modulation based on a second signal slower than the first signal is transmitted from the transmission device. An optical branching unit that branches after being acquired; and
A delay interference unit that performs delayed interference of the branched optical signal and outputs interference light;
A light detection unit that converts the interference light into an electrical signal;
A rectifying unit for full-wave rectification of the electrical signal;
A low-speed signal acquisition unit that acquires the second signal based on the full-wave rectified electrical signal;
A high-speed signal acquisition unit that acquires the first signal based on the other branched optical signal. - 前記低速信号変調部は、前記高速信号位相変調部が出力した前記光信号を前記第2の信号に応じて位相変調する低速信号位相変調部を備える請求項1に記載の送信装置。 The transmission apparatus according to claim 1, wherein the low-speed signal modulation unit includes a low-speed signal phase modulation unit that phase-modulates the optical signal output from the high-speed signal phase modulation unit according to the second signal.
- 前記光分岐部は、前記第1の信号に応じて位相シフト量をπとした位相変調を行ってから前記第2の信号に応じて位相変調した光信号を前記送信装置から取得し、
前記低速信号取得部は、前記全波整流した前記電気信号をデコードして前記第2の信号を取得する低速信号デコード部を備え、
前記高速信号取得部は、前記分岐した前記他方の光信号を前記取得した第2の信号に応じて位相変調する位相変調部と、前記位相変調部で位相変調した光信号を受信して前記第1の信号を取得する高速光受信部とを備える請求項2に記載の受信装置。 The optical branching unit obtains, from the transmission device, an optical signal that is phase-modulated according to the second signal after performing phase modulation with a phase shift amount π according to the first signal,
The low-speed signal acquisition unit includes a low-speed signal decoding unit that acquires the second signal by decoding the electric signal subjected to full-wave rectification,
The high-speed signal acquisition unit receives the optical signal that has been phase-modulated by the phase modulation unit and the phase modulation unit that phase-modulates the other optical signal that has been branched in accordance with the acquired second signal. The receiving device according to claim 2, further comprising: a high-speed optical receiving unit that acquires one signal. - 前記低速信号変調部は、前記第2の信号が入力され、前記第2の信号が所定のレベルであるときに出力信号のパルスレベルを変化させるプリコード部と、前記高速信号位相変調部が出力した前記光信号を前記プリコード部の前記出力信号に応じて位相変調する低速信号位相変調部とを備える請求項1に記載の送信装置。 The low-speed signal modulation unit receives the second signal, and outputs a precoding unit that changes a pulse level of the output signal when the second signal is at a predetermined level, and the high-speed signal phase modulation unit outputs The transmission apparatus according to claim 1, further comprising: a low-speed signal phase modulation unit that phase-modulates the optical signal according to the output signal of the precoding unit.
- 前記光分岐部は、前記第1の信号に応じて位相シフト量をπとした位相変調を行った光信号を、前記第2の信号が所定のレベルであるときにパルスレベルを変化させた信号に応じて位相変調した光信号を前記送信装置から取得し、
前記低速信号取得部は、前記全波整流された前記電気信号を検波して前記第2の信号を取得する低速信号検波部を備え、
前記高速信号取得部は、前記分岐した前記他方の光信号を前記取得した第2の信号に応じて位相変調する位相変調部と、前記位相変調部で位相変調した光信号を受信して前記第1の信号を取得する高速光受信部とを備える請求項2に記載の受信装置。 The optical branching unit is a signal obtained by changing a pulse level of an optical signal that has been subjected to phase modulation with a phase shift amount of π according to the first signal when the second signal is at a predetermined level. To obtain an optical signal phase-modulated according to the transmitter,
The low-speed signal acquisition unit includes a low-speed signal detection unit that detects the full-wave rectified electrical signal and acquires the second signal,
The high-speed signal acquisition unit receives the optical signal that has been phase-modulated by the phase modulation unit and the phase modulation unit that phase-modulates the other optical signal that has been branched in accordance with the acquired second signal. The receiving device according to claim 2, further comprising: a high-speed optical receiving unit that acquires one signal. - 前記低速信号変調部は、周波数が前記第1の信号のシンボルレートの半分であるクロック信号を出力するクロック出力部と、前記第2の信号と前記クロック信号の論理積を出力する論理積演算部と、前記高速信号位相変調部が出力した前記光信号を前記論理積演算部が出力した信号に応じて位相変調する低速信号位相変調部とを備える請求項1に記載の送信装置。 The low-speed signal modulation unit includes a clock output unit that outputs a clock signal whose frequency is half the symbol rate of the first signal, and a logical product operation unit that outputs a logical product of the second signal and the clock signal. And a low-speed signal phase modulation unit that phase-modulates the optical signal output from the high-speed signal phase modulation unit according to a signal output from the AND operation unit.
- 前記光分岐部は、前記第1の信号に応じて位相シフト量をπとした位相変調を行った光信号を、周波数が前記第1の信号のシンボルレートの半分であるクロック信号と前記第2の信号との論理積に応じて位相変調した光信号を前記送信装置から取得し、
前記低速信号取得部は、前記全波整流された前記電気信号を検波して前記第2の信号を取得する低速信号検波部を備え、
前記高速信号取得部は、前記分岐した前記他方の光信号を前記取得した第2の信号に応じて位相変調する位相変調部と、前記位相変調部で位相変調した光信号を受信して前記第1の信号を取得する高速光受信部とを備える請求項2に記載の受信装置。 The optical branching unit converts an optical signal obtained by performing phase modulation with a phase shift amount π in accordance with the first signal, a clock signal having a frequency that is half the symbol rate of the first signal, and the second signal An optical signal phase-modulated according to the logical product with the signal of
The low-speed signal acquisition unit includes a low-speed signal detection unit that detects the full-wave rectified electrical signal and acquires the second signal,
The high-speed signal acquisition unit receives the optical signal that has been phase-modulated by the phase modulation unit and the phase modulation unit that phase-modulates the other optical signal that has been branched in accordance with the acquired second signal. The receiving device according to claim 2, further comprising: a high-speed optical receiving unit that acquires one signal. - 前記低速信号変調部は、前記高速信号位相変調部が出力した前記光信号を前記第2の信号に応じて周波数変調する周波数変調部を備える請求項1に記載の送信装置。 The transmission device according to claim 1, wherein the low-speed signal modulation unit includes a frequency modulation unit that frequency-modulates the optical signal output from the high-speed signal phase modulation unit according to the second signal.
- 前記光分岐部は、前記第1の信号に応じて位相シフト量をπとした位相変調を行ってから前記第2の信号に応じて周波数変調した光信号を前記送信装置から取得し、
前記低速信号取得部は、前記全波整流した前記電気信号を検波して前記第2の信号を取得する低速信号検波部を備え、
前記高速信号取得部は、前記分岐した前記他方の光信号を受信して前記第1の信号を取得する高速光受信部を備える請求項2に記載の受信装置。 The optical branching unit obtains, from the transmission device, an optical signal that has been subjected to phase modulation with a phase shift amount π according to the first signal and then frequency-modulated according to the second signal,
The low-speed signal acquisition unit includes a low-speed signal detection unit that detects the full-wave rectified electrical signal and acquires the second signal,
The receiving apparatus according to claim 2, wherein the high-speed signal acquisition unit includes a high-speed optical reception unit that receives the branched optical signal and acquires the first signal. - 前記高速信号取得部は、前記分岐した前記他方の光信号を前記取得した第2の信号に応じて周波数変調する周波数変調部をさらに備え、
前記高速光受信部は、前記周波数変調部で周波数変調した光信号を受信して前記第1の信号を取得する請求項10に記載の受信装置。 The high-speed signal acquisition unit further includes a frequency modulation unit that modulates the frequency of the branched optical signal according to the acquired second signal,
The receiving device according to claim 10, wherein the high-speed optical receiver receives the optical signal frequency-modulated by the frequency modulator and acquires the first signal. - 前記遅延干渉部は、前記第1の信号の1シンボル時間または前記第2の信号の1シンボル時間を遅延量として遅延干渉を行う請求項4、請求項6、請求項10、請求項11の何れかに記載の受信装置。 The delay interference unit performs delay interference using one symbol time of the first signal or one symbol time of the second signal as a delay amount. A receiving device according to claim 1.
- 前記低速信号位相変調部は、位相シフト量をπ/2として位相変調する請求項3、請求項5、請求項7の何れかに記載の送信装置。 The transmission device according to any one of claims 3, 5, and 7, wherein the low-speed signal phase modulation unit performs phase modulation with a phase shift amount of π / 2.
- 前記位相変調部は、位相シフト量をπ/2として位相変調する請求項4、請求項6、請求項8の何れかに記載の受信装置。 The receiving device according to any one of claims 4, 6, and 8, wherein the phase modulation unit performs phase modulation with a phase shift amount of π / 2.
- 前記周波数変調部は、前記送信部から送信される前記光信号を前記受信装置で遅延干渉させる際の遅延量の逆数の1/4に相当する周波数を周波数シフト量として周波数変調を行う請求項9に記載の送信装置。 The frequency modulation unit performs frequency modulation using a frequency corresponding to ¼ of a reciprocal of a delay amount when the optical signal transmitted from the transmission unit is subjected to delay interference by the receiver as a frequency shift amount. The transmitting device according to 1.
- 前記周波数変調部は、前記遅延干渉部の遅延量の逆数の1/4に相当する周波数を周波数シフト量として周波数変調を行う請求項11に記載の受信装置。 The receiving apparatus according to claim 11, wherein the frequency modulation unit performs frequency modulation using a frequency corresponding to ¼ of a reciprocal of the delay amount of the delay interference unit as a frequency shift amount.
- 請求項1に記載の送信装置および請求項2に記載の受信装置、または、
請求項3に記載の送信装置および請求項4に記載の受信装置、または、
請求項5に記載の送信装置および請求項6に記載の受信装置、または、
請求項7に記載の送信装置および請求項8に記載の受信装置、または、
請求項9または請求項15に記載の送信装置および請求項10、請求項11または請求項16のいずれかに記載の受信装置を備える光伝送システム。 The transmitting device according to claim 1 and the receiving device according to claim 2, or
The transmission device according to claim 3 and the reception device according to claim 4, or
The transmission device according to claim 5 and the reception device according to claim 6, or
The transmission device according to claim 7 and the reception device according to claim 8, or
An optical transmission system comprising: the transmission device according to claim 9 or claim 15; and the reception device according to claim 10, 11 or 16. - 速度が異なる2つの信号を1つの光信号に多重して送信する光伝送方法であって、
第1の信号を出力し、
前記第1の信号に応じて、位相シフト量をπとした位相変調を行って位相変調された光信号を出力し、
前記第1の信号よりも低速な第2の信号を出力し、
前記第2の信号に基づいて、前記位相変調された光信号の位相変調または周波数変調を行って受信装置に送信する光伝送方法。 An optical transmission method in which two signals having different speeds are multiplexed and transmitted in one optical signal,
Output a first signal;
In accordance with the first signal, a phase modulation with a phase shift amount of π is performed and a phase modulated optical signal is output,
Outputting a second signal that is slower than the first signal;
An optical transmission method for performing phase modulation or frequency modulation on the phase-modulated optical signal based on the second signal and transmitting the result to a receiving apparatus. - 速度が異なる2つの信号を多重した1つの光信号を受信する光伝送方法であって、
第1の信号に応じて位相シフト量をπとした位相変調を行ってから前記第1の信号よりも低速な第2の信号に基づいて位相変調または周波数変調した光信号を送信装置から取得して分岐し、
前記分岐した一方の光信号の遅延干渉を行い、干渉光を出力し、
前記干渉光を電気信号に変換し、
前記電気信号を全波整流し、
前記全波整流した電気信号に基づいて前記第2の信号を取得し、
前記分岐した他方の光信号に基づいて前記第1の信号を取得する光伝送方法。 An optical transmission method for receiving one optical signal obtained by multiplexing two signals having different speeds,
An optical signal obtained by performing phase modulation with a phase shift amount π according to the first signal and then phase-modulating or frequency-modulating based on the second signal that is slower than the first signal is acquired from the transmission device. Branch off
Perform delayed interference of the branched one optical signal, and output interference light,
Converting the interference light into an electrical signal;
Full-wave rectification of the electrical signal,
Obtaining the second signal based on the full-wave rectified electrical signal;
An optical transmission method for obtaining the first signal based on the other branched optical signal.
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