CN117768027A - Optical signal modulation and monitoring method and related device - Google Patents
Optical signal modulation and monitoring method and related device Download PDFInfo
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Abstract
The embodiment of the application discloses an optical signal modulation and monitoring method and a related device, which are used for reducing pilot crosstalk caused by SRS effect. The optical signal modulation method comprises the following steps: modulating a first pilot frequency and a second pilot frequency for a wavelength in an optical signal to obtain the first pilot frequency signal and the second pilot frequency signal of the wavelength, wherein the first pilot frequency is not equal to the second pilot frequency; the first pilot signal and the second pilot signal are output so that the optical signal monitoring device calculates the signal power of the wavelength from the power of the beat frequency of the first pilot signal and the second pilot signal. First, the first pilot frequency and the second pilot frequency are modulated for the wavelength in the optical signal by receiving the optical signal, and finally the power of the wavelength is reflected by calculating the power of the beat frequency, so that the SRS crosstalk power is reduced and the error of monitoring the optical power of the wavelength signal is reduced compared with the traditional scheme.
Description
Technical Field
The present disclosure relates to the field of optical transmission, and in particular, to an optical signal modulation and monitoring method and related device.
Background
To ensure reliable operation of a wavelength division multiplexing (wavelength division multiplexing, WDM) system, reducing disruption caused by network failure, it is critical to monitor the performance of each WDM wavelength channel using low cost methods. Optical tagging, i.e., pilot tone (pilot tone) is a very potential optical network monitoring technology. The optical tag monitoring technique allocates different pilot tones for each channel at the transmitting end, and the receiving end typically includes a low-speed photodiode and a digital signal processor (digital signal processor, DSP) to obtain the tag signals for all channels of the fiber. Because the frequencies of the tag signals on different channels are different, the tag signals can be simultaneously received by one receiver, thereby realizing the performance monitoring of all wavelength channels. The optical tag not only has unique wavelength channel connection state monitoring capability, but also has the advantages of low cost and rich monitoring functions. However, due to the effects of stimulated raman scattering (stimulated Raman scattering, SRS) in DWDM systems, the tag signal acts as a monitoring index in wavelength link monitoring schemes, with significant crosstalk between different wavelength channels, especially under long-range and multi-channel transmission conditions. The SRS effect causes the transfer of pilot signals with different wavelengths, so that the optical label cannot accurately monitor the power of the wavelength channel, which is the basis for monitoring other performances, so that the system generates obvious errors on the estimation of the optical power of each wavelength signal, which is unfavorable for the system transmission.
The scheme for suppressing the SRS effect based on the tunable optical filter is as follows: each wavelength is filtered out in turn by an adjustable optical filter, received using the same photodiode, each wavelength channel is detected in turn, and the corresponding optical power is calculated. The wavelength channels are separated in time, and crosstalk between the pilot signal and other wavelength channels is isolated, thus eliminating interference. The scheme for restraining SRS effect based on the band filter is as follows: because the larger the wavelength interval is, the more serious the SRS crosstalk is, the optical signals are divided into two long and short wavebands by utilizing the waveband filter, the optical signals with the most serious crosstalk and larger wavelength interval are spatially isolated, and the photoelectric conversion and pilot signal monitoring are respectively and independently carried out, so that the crosstalk is reduced. The tunable optical filter scheme requires the use of an expensive tunable optical filter, which is costly, while the band filter scheme requires the use of a plurality of photodiodes and pilot signal monitoring devices in parallel, which is complex in structure, and the better the SRS suppression effect, the higher the complexity.
Therefore, how to reduce pilot crosstalk caused by SRS effect is a main problem to be solved by this patent.
Disclosure of Invention
The embodiment of the application provides an optical signal modulation and monitoring method and a related device, which are used for reducing pilot crosstalk caused by SRS effect.
In a first aspect, the present application provides an optical signal modulation method, which is characterized by comprising:
and modulating the first pilot frequency and the second pilot frequency for the wavelength in the optical signal to obtain a first pilot frequency signal and a second pilot frequency signal of the wavelength, wherein the first pilot frequency is not equal to the second pilot frequency. In a WDM communication system, after optical signals of a plurality of wavelengths emitted by an optical source of a transmitter are multiplexed by a wavelength division multiplexer, a multiplexed signal including the optical signals of the plurality of wavelengths can be obtained, so that two different pilot signals can be modulated for each wavelength in an optical modulator of the transmitter or by an external modulation device.
The first pilot signal and the second pilot signal are output so that the optical signal monitoring device calculates the signal power of the wavelength from the power of the beat frequency of the first pilot signal and the second pilot signal. After modulating the wavelength in the optical signal, the modulated first pilot signal and the modulated second pilot signal are output. The first pilot signal and the second pilot signal can be sent out by a transmitter, after an optical signal monitoring device in the WDM communication system receives the first pilot signal and the second pilot signal, beat frequency of the two pilot signals is calculated first, then optical signal power of the beat frequency is calculated, and finally the power of the beat frequency is used for reflecting the power of the wavelength.
In this embodiment, by receiving the optical signal, the first pilot frequency and the second pilot frequency are modulated for the wavelength in the optical signal, and finally the power of the wavelength is reflected by calculating the power of the beat frequency. Compared with the traditional scheme, the SRS crosstalk power is reduced, and the error of the monitoring wavelength signal light power is reduced.
In one possible implementation, the modulating the first pilot and the second pilot for the wavelength in the optical signal specifically includes:
dividing the optical signal into two orthogonal polarization states;
when modulating signals in polarization state, the first pilot frequency and the second pilot frequency are modulated for signals corresponding to wavelengths.
It will be appreciated that in an optical communication process, after an optical source (e.g., a laser) emits an optical signal, the optical modulator of the transmitter splits the light into two orthogonal polarization states and modulates the signal for both polarization states, so that the first pilot and the second pilot can be modulated for the signal when modulating the amplitude for the wavelength.
In one possible implementation method, when modulating a signal in a polarization state, modulating a first pilot frequency and a second pilot frequency for a signal corresponding to a wavelength specifically includes:
Quadrature amplitude modulation is carried out on the polarization states to obtain a first polarization state real part signal, a first polarization state imaginary part signal, a second polarization state real part signal and a second polarization state imaginary part signal of the wavelength;
the first pilot and the second pilot are modulated for each of the first polarization real signal, the first polarization imaginary signal, the second polarization real signal, and the second polarization imaginary signal.
It will be appreciated that after the optical modulator will split the light into two orthogonal polarization states, the polarization states may also be quadrature amplitude modulated.
In one possible implementation method, the first and second modules,
the optical signal comprises N wavelengths, wherein N is an integer greater than 0;
the frequency interval between the first pilots of the N wavelengths is a first interval;
the frequency interval between the second pilots of the N wavelengths is a second interval;
the first interval is not equal to the second interval.
It will be appreciated that two pilot signals with different frequencies are modulated for each wavelength, for the sake of convenience of calculation, each first pilot forms an arithmetic series with a tolerance of a first interval, each second pilot forms an arithmetic series with a tolerance of a second interval, and since the first interval is not equal to the second interval, the pilot signal differences between the wavelengths are different, and the beat frequency between the pilots of the two wavelengths is not the same when the beat frequency is calculated.
In a second aspect, the present application provides an optical signal monitoring method, including:
acquiring a first pilot signal and a second pilot signal, wherein the first pilot signal and the second pilot signal are pilot signals with the same wavelength, and the frequencies of the first pilot signal and the second pilot signal are different;
calculating the beat frequency power of the first pilot signal and the second pilot signal;
and calculating the signal power of the wavelength according to the power of the beat frequency.
It can be appreciated that by obtaining two pilot signals of different frequencies for each wavelength, the beat power of the two pilot signals is calculated, and the signal power for each wavelength is calculated using the beat power, the SRS crosstalk power is reduced by 10log relative to the direct calculation of the pilot power 10 (K) dB, therefore, the optical signal monitoring method provided by the application achieves the aim of reducing SRS crosstalk under the conditions of not increasing cost and not introducing extra errors.
In one possible implementation method, calculating the power of the beat frequencies of the first pilot signal and the second pilot signal specifically includes:
and carrying out Fourier transformation on the beat frequency of the first pilot frequency signal and the second pilot frequency signal in the preset time to obtain the power of the beat frequency.
In a third aspect, the present application provides an optical signal modulation apparatus, including:
The modulation module is used for modulating the first pilot frequency and the second pilot frequency for the wavelength in the optical signal to obtain a first pilot frequency signal and a second pilot frequency signal of the wavelength, wherein the first pilot frequency is not equal to the second pilot frequency;
and the transmitting module is used for outputting the first pilot signal and the second pilot signal so that the optical signal monitoring device can obtain the signal power of the wavelength by calculating the beat frequency power of the first pilot signal and the second pilot signal.
In one possible implementation method, the first and second modules,
the modulation module is specifically used for dividing the optical signal into two orthogonal polarization states; when modulating signals in polarization state, the first pilot frequency and the second pilot frequency are modulated for signals corresponding to wavelengths.
In one possible implementation method, the first and second modules,
the modulation module is specifically used for carrying out quadrature amplitude modulation on the polarization states to obtain a first polarization state real part signal, a first polarization state imaginary part signal, a second polarization state real part signal and a second polarization state imaginary part signal of the wavelength; the first pilot and the second pilot are modulated for each of the first polarization real signal, the first polarization imaginary signal, the second polarization real signal, and the second polarization imaginary signal.
In one possible implementation method, the first and second modules,
the optical signal comprises N wavelengths, wherein N is an integer greater than 0;
The frequency interval between the first pilots of the N wavelengths is a first interval;
the frequency interval between the second pilots of the N wavelengths is a second interval;
the first interval is not equal to the second interval.
In one possible implementation, the apparatus is embodied as a bi-biased IQ modulator.
In a fourth aspect, the present application provides an optical signal monitoring device, including:
the receiving module is used for acquiring a first pilot signal and a second pilot signal, wherein the first pilot signal and the second pilot signal are pilot signals with the same wavelength, and the frequencies of the first pilot signal and the second pilot signal are different;
the processing module is used for calculating the beat frequency power of the first pilot signal and the second pilot signal;
and the processing module is also used for calculating the signal power of the wavelength according to the power of the beat frequency.
In one possible implementation method, the processing module is specifically configured to perform fourier transform on the beat frequencies of the first pilot signal and the second pilot signal in a preset time, so as to obtain the power of the beat frequency.
In one possible implementation, the receiving module, in particular the photodiode PD.
In one possible implementation, the processing module is in particular a digital signal processing device DSP.
In a fifth aspect, the present application provides an optical transmission system, including the optical signal modulation device according to the third aspect and the optical signal monitoring device according to the fourth aspect.
A sixth aspect of the present application provides a computer readable storage medium storing a computer program or instructions for, when executed by one or more computers, causing the one or more computers to carry out the method of any possible implementation of any of the aspects described above.
A seventh aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any of the aspects described above.
An eighth aspect of the present application provides a chip apparatus, comprising a processor, configured to be connected to a memory, and call a program stored in the memory, so that the processor performs any implementation manner of the first aspect.
Drawings
Fig. 1 is a flowchart of a method for modulating an optical signal according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of an optical transmission system according to an embodiment of the present application;
Fig. 3 is a schematic diagram of two pilot distributions of each wavelength in the embodiment of the present application;
fig. 4 is a beat frequency distribution diagram of two pilots of each wavelength in the embodiment of the present application;
fig. 5 is a graph of suppression effect on SRS in the embodiment of the present application;
fig. 6 is a schematic diagram of an optical modulation principle of a transmitter according to an embodiment of the present application;
fig. 7 is a method flowchart of an optical signal monitoring method according to an embodiment of the present application;
fig. 8 is a schematic structural diagram of an optical signal modulation device according to an embodiment of the present application;
fig. 9 is a schematic structural diagram of an optical signal monitoring device according to an embodiment of the present application;
fig. 10 is a schematic structural diagram of a pilot receiver according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. As a person of ordinary skill in the art can know, with the appearance of a new application scenario, the technical solution provided in the embodiment of the present application is applicable to similar technical problems.
The terms first, second and the like in the description and in the claims of the present application and in the above-described figures, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments described herein may be implemented in other sequences than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or modules is not necessarily limited to those steps or modules that are expressly listed or inherent to such process, method, article, or apparatus. The naming or numbering of the steps in the present application does not mean that the steps in the method flow must be executed according to the time/logic sequence indicated by the naming or numbering, and the execution sequence of the steps in the flow that are named or numbered may be changed according to the technical purpose to be achieved, so long as the same or similar technical effects can be achieved. The division of the units in the present application is a logic division, and may be implemented in another manner in practical application, for example, a plurality of units may be combined or integrated in another system, or some features may be omitted or not implemented, and in addition, coupling or direct coupling or communication connection between the units shown or discussed may be through some interfaces, and indirect coupling or communication connection between the units may be electrical or other similar manners, which are not limited in this application. The units or sub-units described as separate components may or may not be physically separate, may or may not be physical units, or may be distributed in a plurality of circuit units, and some or all of the units may be selected according to actual needs to achieve the purposes of the present application.
The pilot tone is a small and low frequency modulation applied to a high-speed optical channel, and can be modulated by performing additional low frequency intensity modulation on a modulated broadband optical signal envelope, wherein the modulation depth is defined as 0.01 to 0.2: (maximum power of optical signal-minimum power of optical signal)/average power of optical signal. Typically for a wavelength division multiplexed optical transmission system, there will be several communication wavelengths, such as lambda 1 ，λ 2 ，λ 3 …, etc. (typical values are those containing 80 wavelengths, i.e. lambda 1 To lambda 80 ). Each wavelength lambda k A high-speed optical signal, such as a PDM-QPSK signal of 50-100GBaud, may be modulated. In order to realize the monitoring function of the power of each wavelength, the power of each wavelength can be represented by lambda 1 Up-modulating a frequency of f 1 Is a sinusoidal intensity modulated signal at lambda 2 Up-modulating a frequency of f 2 Is a sinusoidal intensity modulated signal at lambda 3 Up-modulating a frequency of f 3 And so on.
When the optical fiber exists more serious stimulated Raman scatteringAt a wavelength lambda 1 A certain ratio of the power of (2) is transferred to lambda 2 ，λ 3 On … (assume here a wavelength lambda 1 ＜λ 2 ＜λ 3 …). Further result in a wavelength lambda 1 Pilot f on 1 Partial power transfer to lambda 2 ，λ 3 ….
When the wavelength lambda is 1 After a certain node of the transmission link, if the SRS does not exist, the photoelectric detector does not receive the frequency f 1 Is a power signal of (a); when SRS exists, the electric detector receives pilot signals of a plurality of wavelength channels at the same time, and crosstalk on other wavelength channels and the pilot signals on the wavelength channels are in the same frequency and cannot be distinguished. Therefore, crosstalk generated by SRS effects introduces errors in calculating the optical power of the present wavelength channel, and also introduces interference in determining the state of the present wavelength channel.
After modulating a pilot for the wavelength:
let the wavelength lambda 1 The signal after loading pilot can be expressed as:
s(t)·(1+m·cosωt) (1)
where s (t) is a signal and (1+m·cos ωt) is a pilot.
The detection by a Photodiode (PD) of the optical signal monitoring device can be expressed as follows (assuming a PD responsivity of 1):
I＝|s(t)| 2 |1+m·cosωt| 2 ＝|s(t)| 2 ·(1+2m·cosωt+m 2 cos 2 ωt) (2)
wherein 1 is a direct current term, m 2 ·cos 2 ωt is a high frequency term, 2m.cos ωt is a pilot term, and its power is 2m 2 ·P s Wherein P is s Is the power of the signal s (t).
SRS transition to lambda 2 The above signals are:
crosstalk signals are obtained after PD detection (assuming that the PD responsivity is 1):
crosstalk pilot termIts power is +.>Wherein K is Raman transfer efficiency, and K is more than 1.
At this time, the Raman crosstalk-pilot signal ratio is
In order to solve pilot crosstalk caused by SRS, two solutions are proposed in the related art, including an optical banded method and a high-frequency pilot method.
The optical striping method refers to striping an optical signal with a filter or a filter according to a certain rule before a PD of the optical signal monitoring device receives a pilot signal, for example: the optical signal of 1530-1560nm is divided into 1530-1538nm,1538-1545nm,1545-1552nm and 1552-1560nm by the filter plate, and the total wave bands are 4; optical signals of 1530-1560nm are divided into even channels and odd channels by analogy by comb filters according to 1530 + -0.5 nm,1532 + -0.5 nm,1534 + -0.5 nm …, and 1531 + -0.5 nm,1533 + -0.5 nm,1534 + -0.5 nm …. The principle is to attenuate pilot crosstalk caused by SRS transfer by filtering an optical signal. The rule of reducing crosstalk of the method is that SRS crosstalk can be reduced to 1/N of original crosstalk by dividing the SRS crosstalk into N optical bands, so that at least N PDs are needed to detect each optical band, and in addition, a plurality of filters or filters are needed to realize the zoning of optical signals, so that cost is greatly increased, and commercial application is not facilitated.
The high-frequency pilot method is to suppress pilot crosstalk caused by SRS by raising the pilot frequency. The pilot frequency is generally 30-60MHz, the method increases the pilot frequency to 120-150MHz, the principle is briefly that the high-frequency pilot has obvious walk-off effect in the transmission process, so that optical signals with different wavelengths cannot always be coherent and constructive in the SRS crosstalk superposition process, and coherent cancellation exists to a certain extent, thereby realizing SRS crosstalk suppression. However, when SRS crosstalk is significantly reduced, the high-frequency pilot frequency has serious frequency fading caused by chromatic dispersion, that is, the signal of the high-frequency pilot frequency has power drop due to the optical fiber itself, and the signal estimation error is increased to affect the system performance, so that the system performance is not easy to be improved, the influence of crosstalk is reduced, but obvious cost is paid.
In order to solve the above-mentioned problem, a first aspect of the present application provides an optical signal modulation method, which may be performed by an optical modulator of a transmitter in a WDM communication system or by an external modulation device, for modulating an optical signal in the WDM communication system.
Referring to fig. 1, fig. 1 is a flowchart of a method for modulating an optical signal according to an embodiment of the present application, including:
and 101, modulating the first pilot frequency and the second pilot frequency for the wavelength in the optical signal to obtain a first pilot frequency signal and a second pilot frequency signal of the wavelength, wherein the first pilot frequency is not equal to the second pilot frequency.
It will be appreciated that in a WDM communication system, a transmitter, a repeater amplification circuit, a receiver and optical signal monitoring means are included. Wherein the transmitter functions to convert the electrical signal into an optical signal and to efficiently transmit the optical signal into the transmission fiber. The transmitter is composed of a light source, an optical modulator, a wavelength division multiplexer and the like, wherein the light source commonly used in optical communication is a laser and a light emitting diode, and an optical signal emitted by the light source is modulated by the optical modulator and then is sent into a transmission optical fiber in a multiplexing signal mode through the wavelength division multiplexer.
In this embodiment, at least two pilots are modulated for each wavelength in the optical signal, and for ease of understanding, the two pilots are a first pilot and a second pilot, respectively. Since the transmitter includes an optical modulator, the step of modulating the pilot may be performed by the optical modulator, or may be performed by an external modulation device, which is not limited in this application.
Specifically, the wavelength lambda 1 The pilot-loaded signal on the pilot can be expressed as
s(t)·(1+m·cosω 1 t+m·cosω 2 t) (5)
Wherein s (t) is a signal, (1+m.cosω) 1 t+m·cosω 2 t) is an indication that two different pilots are modulated on the optical signal.
102, outputting the first pilot signal and the second pilot signal, so that the optical signal monitoring device calculates the signal power of the wavelength by the power of the beat frequency of the first pilot signal and the second pilot signal.
It will be appreciated that a number of optical signals are multiplexed by a wavelength division multiplexer, amplified by an optical amplifier and then transmitted over an optical fiber. Typically, the signal is amplified by an optical amplifier after transmission over 80 km. The amplified signal has 5-20% of its optical power entering the pilot receiver (e.g., a single PD) via the optical coupler. In general, if the transmission distance is 1200km, amplification can be performed once every 80km, and 5-20% of the optical signals can be separated for pilot frequency reception after each amplification.
Referring to fig. 2, fig. 2 is a schematic structural diagram of an optical transmission system according to an embodiment of the present application, including a wavelength division multiplexer, an optical amplifier, an optical fiber, a wavelength division demultiplexer and a pilot receiver as described above, where the wavelength division multiplexer is configured to convert a plurality of wavelengths of an input optical signal T X1 ～T XN Multiplexing, the wavelength division demultiplexer belongs to the receiver, is used for demultiplexing multiplexing signal back into several optical signals; the wavelength division demultiplexer is used for demultiplexing the optical multiplexing signal to obtain an output optical signal R X1 ～R XN The method comprises the steps of carrying out a first treatment on the surface of the The pilot frequency receiver belongs to an optical signal monitoring device, and after pilot frequency receiving is carried out by the pilot frequency receiver which is used by the optical signal monitoring device, the power value of each pilot frequency is analyzed, so that the real optical power of each wavelength optical signal can be known, and the purpose of monitoring the system performance is achieved.
In this embodiment, after the first pilot frequency and the second pilot frequency are modulated by the wavelength in the optical signal, the wavelength signal is transmitted in the optical fiber in the form of the first pilot frequency signal and the second pilot frequency signal, and is analyzed after being received by the pilot frequency receiver of the optical signal monitoring device. After receiving the first pilot frequency and the second pilot frequency of the wavelength, the pilot frequency receiver calculates the beat frequency power of the two pilot frequencies, thereby calculating the signal power of the wavelength. It will be appreciated that in order to avoid that a certain pilot frequency is the same or similar to the beat frequency, the beat frequency needs to be much smaller than the frequency of the pilot signal itself.
The pilot receiver of the optical signal monitoring device may be connected to the optical fiber anywhere or placed at various points of the optical fiber link, for example, before or after each amplifier, after a wavelength division multiplexer, before a wavelength division demultiplexer of the receiver, etc., to monitor and process the pilot signal everywhere.
Wavelength lambda in the above formula (5) 1 The signal after pilot loading can be expressed as follows (assuming PD responsivity is 1) after PD detection:
I＝|s(t)| 2 |1+m·cosω 1 t+m·cosω 2 t| 2
＝|s(t)| 2 ·[1+2m·cosω 1 t+2m·cosω 2 t+m 2 cos 2 ω 1 t+m 2 cos 2 ω 2 t+m 2 cos(ω 1 +ω 2 )t-m 2 cos(ω 1 -ω 2 )t](6)
wherein 1 is a direct current term, m 2 cos 2 ω 1 t，m 2 cos 2 ω 2 t，m 2 cos(ω 1 +ω 2 ) t is a high frequency term, m 2 cos(ω 1 -ω 2 ) t is the beat frequency term of pilot frequency, its power is
Due to SRS transfer to lambda 2 The above signals are:
the crosstalk signal is obtained after PD detection (assuming that the PD responsivity is 1):
the beat term of the crosstalk pilot is:the power is as follows: />
At this time, the Raman crosstalk-pilot signal ratio is
To facilitate understanding, the power spectrum may be converted to logarithmic form, with the lower amplitude components being pulled higher relative to the higher amplitude components, in order to observe periodic signals that are masked in low amplitude noise. Therefore, the SRS crosstalk power is reduced by 10log relative to the traditional scheme by adopting the scheme 10 (K)dB。
According to the optical signal modulation method provided by the embodiment of the application, two pilot signals with different frequencies are modulated for each wavelength respectively, after the optical signal monitoring device obtains the two pilot signals of each wavelength, the beat frequency power of the two pilot signals is calculated, the signal power of each wavelength is further calculated, the beat frequency power of the crosstalk pilot is calculated, and compared with the direct calculation pilot power, the SRS crosstalk power is reduced by 10log 10 (K) dB, therefore, the optical signal modulation method provided by the application achieves the aim of reducing SRS crosstalk under the conditions of not increasing cost and not introducing extra errors.
In one possible implementation, if the optical signal includes N wavelengths, where N is an integer greater than 0, the first pilot and the second pilot satisfy the following rule when the first pilot and the second pilot are modulated for the N wavelengths:
the frequency interval between the first pilots of the N wavelengths is a first interval;
the frequency interval between the second pilots of the N wavelengths is a second interval;
the first interval is not equal to the second interval.
It can be understood that, for the sake of convenience of calculation, each first pilot forms an equipotential array with a tolerance of a first interval, each second pilot forms an equipotential array with a tolerance of a second interval, and since the first interval is not equal to the second interval, the pilot signal differences between the wavelengths are different, and the beat frequency between the pilots of two wavelengths is not the same or similar when the beat frequency is calculated, which is as follows:
referring to fig. 3, fig. 3 is a schematic diagram of two pilot distributions of each wavelength in the embodiment of the present application.
The first set of pilots contains N frequencies with a frequency spacing Δf, expressed as:the second set of pilots also comprises N frequencies with a frequency spacing Δf 1 Expressed by the formula: />Where k is the wavelength number, i.e. the kth wavelength lambda k The two pilots are +.>Wavelength lambda 1 Wherein two pilots are f 1 ，f 2 。
The pilot receiver uses a low bandwidth PD to obtain the beat frequency between two pilot signals in each wavelength. Referring to fig. 4, fig. 4 is a schematic diagram of beat frequency distribution of two pilots of each wavelength according to an embodiment of the present application, expressed by a formula:
wherein k isFor wavelength numberRefers to wavelength lambda k Beat frequency of two pilots in (f) 0 Is of wavelength lambda 1 Beat frequency of two pilots in (f) 0 ＝f 2 -f 1 ，f 0 And Δf 1 Δf is much smaller than the frequency size of the pilot signal itself. Calculating the frequency to +.>The beat frequency power of the corresponding wavelength can be obtained.
It can be understood that the SRS inhibitory effect of the method provided in this embodiment is shown in fig. 5. Lambda (lambda) 1 Is f 1 The second pilot signal has a frequency f 2 ，f 1 And f 2 Is f 0 ＝f 2 -f 1 。λ 2 Is f 1 +Δf, the second pilot signal having a frequency f 2 +Δf 1 ，λ 2 The beat frequency of the first pilot signal and the second pilot signal is f 2 -f 1 +Δf 1 - Δf. Lambda through SRS transfer 1 Pilot transfer to lambda 2 The principle of the method can be briefly described as follows: similar to equation (2) above, assume a wavelength λ 1 Two pilots (f) 1 ，f 2 ) The power is m 2 ·P s Due to the Raman effect, f is similar to the above formula (4) 1 And f 2 Respectively transfer to lambda 2 Power of crosstalk pilot of (a) isWhere K > 1, so that the SRS crosstalk-signal power ratio is +.>Combining the above formula (6), f 1 And f 2 Of the beat frequency f of (2) 0 Power of +.>Due to the Raman effect, in combination with the above equation (8), the beat frequency shifts to lambda 2 The beat power of the crosstalk pilot of +.>The SRS crosstalk-signal power ratio is reduced to be
In one possible implementation, the modulating the first pilot and the second pilot for the wavelength in the optical signal specifically includes:
dividing the optical signal into two orthogonal polarization states;
when modulating signals in polarization state, the first pilot frequency and the second pilot frequency are modulated for signals corresponding to wavelengths.
It will be appreciated that in an optical communication process, after an optical source (e.g., a laser) emits an optical signal, the optical modulator of the transmitter splits the light into two orthogonal polarization states and modulates the signals for the two polarization states, so that the first pilot and the second pilot can be modulated for the signal after the signal is modulated for the wavelength.
Specifically, in one possible implementation manner, when modulating a signal in a polarization state, the first pilot frequency and the second pilot frequency are modulated for a signal corresponding to a wavelength, which specifically includes:
quadrature amplitude modulation is carried out on the polarization states to obtain a first polarization state real part signal, a first polarization state imaginary part signal, a second polarization state real part signal and a second polarization state imaginary part signal of the wavelength;
the first pilot and the second pilot are modulated for each of the first polarization real signal, the first polarization imaginary signal, the second polarization real signal, and the second polarization imaginary signal.
It will be appreciated that after the optical modulator splits the light into two orthogonal polarization states, the polarization states may also be quadrature amplitude adjusted, as follows:
referring to fig. 6, fig. 6 is a schematic diagram illustrating an optical modulation principle of a transmitter according to an embodiment of the present application.
In this embodiment, the light source of the transmitter in the WDM system is a laser, and the optical modulator is a bi-polarized IQ modulator, where the emission wavelength of the laser is λ k Typically in the range 1530-1565nm. The functions realized by the double-bias IQ modulator are as follows: dividing the input DC optical signal into two beams of orthogonal polarization states, and carrying out quadrature amplitude modulation to load an electric signal s xi ，s xq ，s yi ，s yq . Wherein x, y represent two orthogonal polarization states; i, q represent two orthogonal amplitude modulation signals, specifically, a bi-polarized IQ modulator divides the optical signal into a first polarization real part signal s xi Imaginary signal s of first polarization state xq Real part signal s of second polarization state yi And a second polarization state imaginary signal s yq . In the embodiment of the application, the normal signal s is modulated at the transmitter xi (t)，s xq (t)，s yi (t)，s yq At (t), each wavelength modulates two pilot signals of different frequencies. The modulation scheme is shown as DSP in fig. 6, and is expressed as:
where m represents the modulation depth.Representing modulation of pilot frequenciesThe frequency is typically 30-50MHz.
Referring to fig. 10, fig. 10 is a schematic structural diagram of a pilot receiver according to an embodiment of the present application.
About 10% of the optical signal amplified by the optical amplifier (OA, optical amplifier) is input to the pilot receiver via the optical coupler. The pilot receiver includes a low bandwidth PD with a PD bandwidth requirement greater than f 0 +(N-1)(Δf 1 - Δf), and the size of each frequency pilot signal can be obtained after the PD receives and processes the signal. The typical flow of DSP processing is: assuming that the electrical signal received by the PD is PT (t), t represents time, and each beat frequency can be obtained through Fourier changePower of-> The FFT (s, f) represents a power value at which the signal s is fourier transformed and the frequency f is output. It will be appreciated that the pilot receiver may be accessed to the optical fiber anywhere or placed at various points of the optical fiber link, such as before or after each amplifier, after a wavelength division multiplexer, before a wavelength division demultiplexer of the receiver, etc., to monitor and process the pilot signal everywhere. It should be noted that, in the embodiment of the present application, a DSP is used to calculate the beat frequency power, so as to obtain the signal power of the corresponding wavelength, and in practical application, the frequency processing method and the power calculating method and steps may be implemented by other formulas or software and applied to other physical or virtual devices, which only provides one possible implementation manner, and does not limit the calculating method and the processing device.
A second aspect of the present application provides an optical signal monitoring method that may be performed by an optical signal monitoring device in a WDM communication system.
Referring to fig. 7, fig. 7 is a method flowchart of an optical signal monitoring method according to an embodiment of the present application, including:
701, a first pilot signal and a second pilot signal are acquired, the first pilot signal and the second pilot signal are pilot signals with the same wavelength, and the frequencies of the first pilot signal and the second pilot signal are different.
It can be understood that after pilot frequency receiving is performed by the pilot frequency receiver of the optical signal monitoring device, the power value of each pilot frequency is analyzed, so that the real optical power of each wavelength optical signal can be known, and the purpose of monitoring the system performance is achieved. In the embodiment of the present application, each wavelength of the optical signals transmitted in the optical fiber is modulated with at least two pilots, that is, the optical signal of one wavelength corresponds to at least two pilot signals. Thus, to monitor the performance of the optical transmission system, first a first pilot signal and a second pilot signal of that wavelength are received. Although the embodiments of the present application will be described with respect to only one wavelength optical signal, in practice, in a WDM system, a composite signal formed by combining optical signals of a plurality of wavelengths is transmitted through an optical fiber.
The pilot receiver of the optical signal monitoring device may be connected to the optical fiber anywhere or placed at various points of the optical fiber link, for example, before or after each amplifier, after a wavelength division multiplexer, before a wavelength division demultiplexer of the receiver, etc., to monitor and process the pilot signal everywhere.
The power of the beat frequencies of the first pilot signal and the second pilot signal is calculated 702.
It can be appreciated that after the first pilot signal and the second pilot signal are obtained, the signal power of the wavelength is calculated by calculating the beat power of the two pilots. It will be appreciated that in order to avoid that a certain pilot frequency is the same or similar to the beat frequency, the beat frequency needs to be much smaller than the frequency of the pilot signal itself. The relevant steps of the calculation are shown in the formulas (5) to (8) of the first embodiment, and will not be described herein.
703, calculating the signal power of the wavelength according to the power of the beat frequency.
It can be understood that the signal power of the corresponding wavelength is calculated by the power of the beat frequency, so as to realize the performance monitoring of the wavelength channel.
Specifically, the pilot receiver comprises a low bandwidth PD, and the size of each frequency pilot signal can be obtained through DSP processing after the PD receives the signal. The typical flow of DSP processing is: assuming that the electrical signal received by the PD is PT (t), t represents time, and each beat frequency can be obtained through Fourier change Power of->The FFT (s, f) represents a power value at which the signal s is fourier transformed and the frequency f is output. It will be appreciated that the pilot receiver may be accessed to the optical fiber anywhere or placed at various points of the optical fiber link, such as before or after each amplifier, after a wavelength division multiplexer, before a wavelength division demultiplexer of the receiver, etc., to monitor and process the pilot signal everywhere. It should be noted that, in the embodiment of the present application, a DSP is used to calculate the beat frequency power, so as to obtain the signal power of the corresponding wavelength, and in practical application, the frequency processing method and the power calculating method and steps may be implemented by other formulas or software and applied to other physical or virtual devices, which only provides one possible implementation manner, and does not limit the calculating method and the processing device.
According to the optical signal monitoring method provided by the embodiment of the application, the beat power of two pilot signals is calculated by acquiring the two pilot signals with different frequencies of each wavelength, the signal power of each wavelength is calculated by using the beat power, and compared with the direct calculation of the pilot power, the SRS crosstalk power is reduced by 10log 10 (K) dB, therefore, the optical signal monitoring method provided by the application achieves the aim of reducing SRS crosstalk under the conditions of not increasing cost and not introducing extra errors.
The third aspect of the present application provides an optical signal modulation apparatus, which may be an optical modulator of a transmitter in a WDM communication system, or may be an external modulation device, configured to modulate an optical signal in the WDM communication system.
Referring to fig. 8, fig. 8 is a schematic structural diagram of an optical signal modulation device according to an embodiment of the present application, and an optical signal modulation device 800 includes: a modulation module 801 and a transmission module 802. The transmitting module 802 may transmit the modulated signal, and the modulating module 801 is configured to perform a modulating operation of the optical signal.
For example, the optical signal modulation device 800 is configured to perform the following scheme:
the modulation module 801 is configured to modulate the first pilot and the second pilot for a wavelength in the optical signal, to obtain a first pilot signal and a second pilot signal of the wavelength, where the first pilot is not equal to the second pilot.
And a transmitting module 802, configured to output the first pilot signal and the second pilot signal, so that the optical signal monitoring device obtains the signal power of the wavelength by calculating the power of the beat frequency of the first pilot signal and the second pilot signal.
It will be appreciated that in WDM communication systems, the optical signals from the optical sources are modulated by an optical modulator and passed through a wavelength division multiplexer to be fed into the transmission fibre as multiplexed signals. Therefore, the modulation module may be the optical modulator, or may be an external device of the optical modulator, and it should be noted that the modulation module should be disposed before the wavelength division multiplexer, that is, the optical signal is modulated before being converted into the multiplexed signal. In this embodiment, at least two pilots are modulated for each wavelength in the optical signal, and for ease of understanding, the two pilots are a first pilot and a second pilot, respectively.
In this embodiment, after the first pilot frequency and the second pilot frequency are modulated by the wavelength in the optical signal, the wavelength signal is transmitted in the optical fiber in the form of the first pilot frequency signal and the second pilot frequency signal, and is analyzed after being received by the pilot frequency receiver of the optical signal monitoring device. After receiving the first pilot frequency and the second pilot frequency of the wavelength, the pilot frequency receiver calculates the beat frequency power of the two pilot frequencies, thereby calculating the signal power of the wavelength. It will be appreciated that in order to avoid that a certain pilot frequency is the same or similar to the beat frequency, the beat frequency needs to be much smaller than the frequency of the pilot signal itself.
In one possible implementation, if the optical signal includes N wavelengths, where N is an integer greater than 0, the first pilot and the second pilot satisfy the following rule when the first pilot and the second pilot are modulated for the N wavelengths:
the frequency interval between the first pilots of the N wavelengths is a first interval;
the frequency interval between the second pilots of the N wavelengths is a second interval;
the first interval is not equal to the second interval.
It will be appreciated that two pilot signals with different frequencies are modulated for each wavelength, for the sake of convenience of calculation, each first pilot forms an arithmetic series with a tolerance of a first interval, each second pilot forms an arithmetic series with a tolerance of a second interval, and since the first interval is not equal to the second interval, the pilot signal differences between the wavelengths are different, and the beat frequency between the pilots of the two wavelengths is not the same or similar when the beat frequency is calculated.
In one possible implementation of the present invention,
the modulation module 801 is specifically configured to split an optical signal into two orthogonal polarization states; when modulating signals in polarization state, the first pilot frequency and the second pilot frequency are modulated for signals corresponding to wavelengths.
It will be appreciated that in an optical communication process, after an optical signal is transmitted by an optical source (e.g., a laser), the optical modulator of the transmitter splits the light into two orthogonal polarization states and modulates the amplitude signal for the two polarization states, so that the first pilot and the second pilot can be modulated for the signal after the signal is modulated for the wavelength.
In particular, in one possible implementation,
the modulation module 801 is specifically configured to perform quadrature amplitude modulation on a polarization state to obtain a first polarization state real part signal, a first polarization state imaginary part signal, a second polarization state real part signal, and a second polarization state imaginary part signal of a wavelength; the first pilot and the second pilot are modulated for each of the first polarization real signal, the first polarization imaginary signal, the second polarization real signal, and the second polarization imaginary signal.
It will be appreciated that after the optical modulator will split the light into two orthogonal polarization states, the polarization states may also be quadrature amplitude modulated. Therefore, the optical signal modulation device provided in the embodiment of the present application may be a bi-polarized IQ modulator, and the bi-polarized IQ modulator may be an optical modulator of a transmitter, which is specifically as follows:
referring to fig. 6, fig. 6 is a schematic diagram illustrating an optical modulation principle of a transmitter according to an embodiment of the present application.
In this embodiment, the light source of the transmitter in the WDM system is a laser, and the optical modulator is a bi-polarized IQ modulator, where the emission wavelength of the laser is λ k Typically in the range 1530-1565nm. The functions realized by the double-bias IQ modulator are as follows: dividing the input DC optical signal into two beams of orthogonal polarization states, and carrying out quadrature amplitude modulation to load an electric signal s xi ，s xq ，s yi ，s yq . Wherein x, y represent two orthogonal polarization states; i, q represent two orthogonal amplitude modulation signals, specifically, a bi-polarized IQ modulator divides the optical signal into a first polarization real part signal s xi Imaginary signal s of first polarization state xq Real part signal s of second polarization state yi And a second polarization state imaginary signal s yq . In the embodiment of the application, the normal signal s is modulated at the transmitter xi (t)，s xq (t)，s yi (t)，s yq At (t), each wavelength modulates two pilot signals of different frequencies. The modulation scheme is shown as DSP in fig. 6, and is expressed as:
where m represents the modulation depth.Representing the modulation frequency of the pilot, typically 30-50MHz.
A fourth aspect of the present application provides an optical signal monitoring device.
Referring to fig. 9, fig. 9 is a schematic structural diagram of an optical signal monitoring device according to an embodiment of the present application, and an optical signal monitoring device 900 includes: a receiving module 901 and a processing module 902. The receiving module 901 may receive the pilot signal, and the processing module 902 is configured to perform processing calculation on the pilot signal.
For example, the optical signal monitoring apparatus 900 is configured to perform the following scheme:
the receiving module 901 is configured to obtain a first pilot signal and a second pilot signal, where the first pilot signal and the second pilot signal are pilot signals with the same wavelength, and frequencies of the first pilot signal and the second pilot signal are different.
A processing module 902, configured to calculate the beat frequency power of the first pilot signal and the second pilot signal.
The processing module 902 is further configured to calculate a signal power of the wavelength according to the power of the beat frequency.
It can be understood that after pilot frequency receiving is performed by the pilot frequency receiver of the optical signal monitoring device, the power value of each pilot frequency is analyzed, so that the real optical power of each wavelength optical signal can be known, and the purpose of monitoring the system performance is achieved. In the embodiment of the present application, each wavelength of the optical signals transmitted in the optical fiber is modulated with at least two pilots, that is, the optical signal of one wavelength corresponds to at least two pilot signals. Thus, to monitor the performance of the optical transmission system, first a first pilot signal and a second pilot signal of that wavelength are received. Although the embodiments of the present application will be described with respect to only one wavelength optical signal, in practice, in a WDM system, a composite signal formed by combining optical signals of a plurality of wavelengths is transmitted through an optical fiber.
The pilot receiver of the optical signal monitoring device may be connected to the optical fiber anywhere or placed at various points of the optical fiber link, for example, before or after each amplifier, after a wavelength division multiplexer, before a wavelength division demultiplexer of the receiver, etc., to monitor and process the pilot signal everywhere.
It can be appreciated that after the first pilot signal and the second pilot signal are obtained, the signal power of the wavelength is calculated by calculating the beat power of the two pilots. It will be appreciated that in order to avoid that a certain pilot frequency is the same or similar to the beat frequency, the beat frequency needs to be much smaller than the frequency of the pilot signal itself. The relevant steps of the calculation are shown in the formulas (5) to (8) of the first embodiment, and will not be described herein.
It can be understood that the signal power of the corresponding wavelength is calculated by the power of the beat frequency, so as to realize the performance monitoring of the wavelength channel.
In one possible implementation of the present invention,
the processing module 902 is specifically configured to perform fourier transform on the beat frequencies of the first pilot signal and the second pilot signal in a preset time, so as to obtain the power of the beat frequency.
Specifically, the pilot receiver comprises a low bandwidth PD, and the size of each frequency pilot signal can be obtained through DSP processing after the PD receives the signal. The typical flow of DSP processing is: assuming that the electrical signal received by the PD is PT (t), t represents time, and each beat frequency can be obtained through Fourier changePower of->FFT (s, f) represents a power value obtained by performing Fourier transform on the signal s and outputting a frequency f . It will be appreciated that the pilot receiver may be accessed to the optical fiber anywhere or placed at various points of the optical fiber link, such as before or after each amplifier, after a wavelength division multiplexer, before a wavelength division demultiplexer of the receiver, etc., to monitor and process the pilot signal everywhere. It should be noted that, in the embodiment of the present application, a DSP is used to calculate the beat frequency power, so as to obtain the signal power of the corresponding wavelength, and in practical application, the frequency processing method and the power calculating method and steps may be implemented by other formulas or software and applied to other physical or virtual devices, which only provides one possible implementation manner, and does not limit the calculating method and the processing device.
In one possible implementation of the present invention,
the receiving module 901 is specifically a PD.
In one possible implementation of the present invention,
the processing module 902 is in particular a digital signal processing device (digital signal processor, DSP).
A fifth aspect of the present application provides an optical transmission system comprising the optical signal modulation device mentioned in any one of the above aspects and an optical signal monitoring device.
The present embodiments also provide a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of the embodiments as shown in fig. 1 or fig. 7 above.
Embodiments of the present application also provide a computer-readable storage medium comprising computer instructions which, when run on a computer, cause the computer to perform the method of the embodiments shown in fig. 1 or fig. 7 described above.
The embodiment of the application further provides a chip device, which comprises a processor, wherein the processor is connected with the memory, and calls the program stored in the memory, so that the processor executes the method of the embodiment shown in fig. 1 or fig. 7.
The steps of a method or algorithm described in connection with the disclosure herein may be embodied in hardware, or may be embodied in software instructions executed by a processor. The software instructions may be comprised of corresponding software modules that may be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. In addition, the ASIC may reside in a terminal. It is also possible that the processor and the storage medium are present as discrete components in the first communication means.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.
In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied in essence or a part contributing to the prior art or all or part of the technical solution in the form of a software product stored in a storage medium, including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Claims (18)
1. A method of modulating an optical signal, comprising:
modulating a first pilot frequency and a second pilot frequency for a wavelength in an optical signal to obtain the first pilot frequency signal and the second pilot frequency signal of the wavelength, wherein the first pilot frequency is not equal to the second pilot frequency;
the first pilot signal and the second pilot signal are output so that the optical signal monitoring device calculates the signal power of the wavelength through the power of the beat frequency of the first pilot signal and the second pilot signal.
2. The method according to claim 1, characterized in that modulating the first pilot and the second pilot for wavelengths in the optical signal, in particular comprises:
splitting the optical signal into two orthogonal polarization states;
and when the polarization state modulation signal is transmitted, the first pilot frequency and the second pilot frequency are modulated for the signal corresponding to the wavelength.
3. The method according to claim 2, wherein modulating the first pilot and the second pilot for the signal corresponding to the wavelength when modulating the signal in the polarization state, specifically comprises:
quadrature amplitude modulation is carried out on the polarization states to obtain a first polarization state real part signal, a first polarization state imaginary part signal, a second polarization state real part signal and a second polarization state imaginary part signal of the wavelength;
The first pilot and the second pilot are modulated for each of the first polarization state real signal, the first polarization state imaginary signal, the second polarization state real signal, and the second polarization state imaginary signal.
4. A method according to any one of claim 1 to 3, wherein,
the optical signal comprises N wavelengths, wherein N is an integer greater than 0;
the frequency interval between the first pilots of the N wavelengths is a first interval;
the frequency interval between the second pilots of the N wavelengths is a second interval;
the first interval is not equal to the second interval.
5. An optical signal monitoring method, comprising:
acquiring a first pilot signal and a second pilot signal, wherein the first pilot signal and the second pilot signal are pilot signals with the same wavelength, and the frequencies of the first pilot signal and the second pilot signal are different;
calculating the power of the beat frequency of the first pilot signal and the second pilot signal;
and calculating the signal power of the wavelength according to the power of the beat frequency.
6. The method according to claim 5, wherein calculating the power of the beat frequency of the first pilot signal and the second pilot signal comprises:
And carrying out Fourier transformation on the beat frequency of the first pilot frequency signal and the second pilot frequency signal in preset time to obtain the power of the beat frequency.
7. An optical signal modulation device, comprising:
the modulation module is used for modulating a first pilot frequency and a second pilot frequency for the wavelength in the optical signal to obtain a first pilot frequency signal and a second pilot frequency signal of the wavelength, wherein the first pilot frequency is not equal to the second pilot frequency;
and the transmitting module is used for outputting the first pilot signal and the second pilot signal so that the optical signal monitoring device can obtain the signal power of the wavelength by calculating the beat frequency power of the first pilot signal and the second pilot signal.
8. The apparatus of claim 7, wherein the device comprises a plurality of sensors,
the modulation module is specifically configured to divide the optical signal into two orthogonal polarization states; and when the polarization state modulation signal is transmitted, the first pilot frequency and the second pilot frequency are modulated for the signal corresponding to the wavelength.
9. The apparatus of claim 8, wherein the device comprises a plurality of sensors,
the modulation module is specifically configured to perform quadrature amplitude modulation on the polarization state to obtain a first polarization state real part signal, a first polarization state imaginary part signal, a second polarization state real part signal and a second polarization state imaginary part signal of the wavelength; the first pilot and the second pilot are modulated for each of the first polarization state real signal, the first polarization state imaginary signal, the second polarization state real signal, and the second polarization state imaginary signal.
10. The device according to any one of claims 7 to 9, wherein,
the optical signal comprises N wavelengths, wherein N is an integer greater than 0;
the frequency interval between the first pilots of the N wavelengths is a first interval;
the frequency interval between the second pilots of the N wavelengths is a second interval;
the first interval is not equal to the second interval.
11. The apparatus according to any of the claims 7 to 10, characterized in that the apparatus is in particular a bi-biased IQ modulator.
12. An optical signal monitoring device, comprising:
the receiving module is used for acquiring a first pilot signal and a second pilot signal, wherein the first pilot signal and the second pilot signal are pilot signals with the same wavelength, and the frequencies of the first pilot signal and the second pilot signal are different;
a processing module, configured to calculate the power of the beat frequencies of the first pilot signal and the second pilot signal;
the processing module is further configured to calculate signal power of the wavelength according to the beat frequency power.
13. The apparatus of claim 12, wherein the device comprises a plurality of sensors,
the processing module is specifically configured to perform fourier transform on beat frequencies of the first pilot signal and the second pilot signal in a preset time, so as to obtain power of the beat frequencies.
14. The apparatus according to claim 12 or 13, characterized in that the receiving module, in particular a photodiode PD.
15. The device according to any of the claims 12 to 14, characterized in that the processing module is in particular a digital signal processing device DSP.
16. An optical transmission system comprising the optical signal modulation device of any one of claims 7 to 11 and the optical signal monitoring device of any one of claims 12 to 15.
17. A computer storage medium storing one or more instructions which, when executed by one or more computers, cause the one or more computers to implement the method of any one of claims 1 to 6.
18. A computer program product, characterized in that it stores instructions that, when executed by a computer, cause the computer to implement the method of any one of claims 1 to 6.
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