CN2517183Y - Optical signal modulation device of optical communication system - Google Patents

Optical signal modulation device of optical communication system Download PDF

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Publication number
CN2517183Y
CN2517183Y CN 01271841 CN01271841U CN2517183Y CN 2517183 Y CN2517183 Y CN 2517183Y CN 01271841 CN01271841 CN 01271841 CN 01271841 U CN01271841 U CN 01271841U CN 2517183 Y CN2517183 Y CN 2517183Y
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CN
China
Prior art keywords
signal
circuit
modulator
control circuit
optical
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Expired - Lifetime
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CN 01271841
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Chinese (zh)
Inventor
关晓龙
王玉金
***
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to CN 01271841 priority Critical patent/CN2517183Y/en
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Publication of CN2517183Y publication Critical patent/CN2517183Y/en
Priority to PCT/CN2002/000742 priority patent/WO2003047143A1/en
Priority to AU2002344522A priority patent/AU2002344522A1/en
Anticipated expiration legal-status Critical
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50Transmitters
    • H04B10/501Structural aspects
    • H04B10/503Laser transmitters
    • H04B10/505Laser transmitters using external modulation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50Transmitters
    • H04B10/501Structural aspects
    • H04B10/503Laser transmitters
    • H04B10/505Laser transmitters using external modulation
    • H04B10/5057Laser transmitters using external modulation using a feedback signal generated by analysing the optical output
    • H04B10/50575Laser transmitters using external modulation using a feedback signal generated by analysing the optical output to control the modulator DC bias
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50Transmitters
    • H04B10/572Wavelength control

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optics & Photonics (AREA)
  • Optical Communication System (AREA)

Abstract

The utility model relates to an optical signal modulation device used in the optical communication system, comprising an optical modulator, a control circuit, a modulation driver, an optical power splitter, wherein, the control circuit comprises a micro-differential detection unit, a synchronous demodulation unit, a bias formation unit and a clock source; the output beams separated by the optical power splitter are changed into the electrical signals through the micro-difference detection unit and amplified, the synchronous demodulation unit and the output clock of the clock source synchronously demodulate the micro-differential signals, and then the bias voltage integrated by the bias formation unit offsets the modulator through direct current, at the same time, the clock signal of the clock source is also modulated to the electrical signal RF as the perturbation signals of the control circuit. Because the control circuit can detect the micro-differential signals of the output beams, and integrate the micro-differential signals to form the bias voltage, automatically adjust the direct current bias point of the modulator, the bias point is stabile in the 1 / 4 periodic point (half - Power Point), thus, the extinction ratio of the output beams can be stabile at the maximum.

Description

Light signal modulating device in the optical communication system
Technical field
The utility model belongs to optical communication field, and the direct current biasing point that is specifically related in high speed optical communication system or simulated light communication system to regulate by control circuit external modulator makes modulated light signal have the optic modulating device of maximum extinction ratio.
Background technology
Along with the development of dense wave division multipurpose (DWDM) system of the long distance of big capacity, the laser emitting module of original employing electric absorption (EA) modulation system waits restriction can not satisfy the requirement that high speed is grown distance because of when do not had by delustring to warble.Because the commercialization of high speed MZ (Mach-Zehnder) lithium niobate modulator, light lift-off technology based on continuous wave (CW) laser and MZ external modulator is applied in the optical communication system gradually, in this smooth lift-off technology, external modulator must be arranged on the correct direct current biasing point, could protect the light modulating signal output of levying High Extinction Ratio, but the direct current biasing point of external modulator can constantly change along with the variation of external world's ring mirror, therefore need provide a kind of technology that can in good time control bias point automatically.Light modulation techniques is a lot of at present, is exactly a kind of as patent CN2040261, and this patent mainly is that luminous flux is controlled.But by control circuit the direct current biasing point of modulator is stabilized in a bit, makes output light have the technology of maximum extinction ratio, the applicant does not also find to have disclosed data.
Summary of the invention
The utility model is exactly the influence of avoiding being subjected to extraneous ring mirror for the direct current biasing point that makes optical modulator, and it is stabilized on the direct current biasing point, realizes the automatic control of optical modulator, to satisfy high speed optical communication or the simulated light communication requirement to light emission module.
For achieving the above object, the light signal modulating device that is applied to optical communication system that the utility model provides comprises optical modulator, control circuit, modulating driver, optical power distributor, described control circuit produces a perturbation signal and is modulated on the signal of telecommunication RF with the form of amplitude modulation, join optical modulator by modulating driver then, input light is modulated; Control circuit receives the part output light that optical power distributor is told simultaneously, feed back to modulator after therefrom detecting modulator bias point elementary errors signal, make its can be on stable bias point operate as normal, it is characterized in that: described control circuit comprises elementary errors detecting unit, synchronous demodulation unit, offset forming unit and clock source; The output light that described optical power distributor is told is after the elementary errors detecting unit changes into the signal of telecommunication and amplifies, clock synchronization in synchronous demodulation unit and the output of clock source demodulates the elementary errors signal, form bias voltage by the offset forming unit integration then modulator is carried out direct current biasing, the clock signal in described clock source also is modulated on the signal of telecommunication RF as the perturbation signal of control circuit simultaneously.
Elementary errors detecting unit in the above-mentioned light signal modulating device further comprises testing circuit, pre-amplifying circuit and filter amplification circuit, after described testing circuit changes into the signal of telecommunication with light signal, amplify in advance by pre-amplifying circuit earlier, carry out filtering and further amplification through filter amplification circuit then.
Offset forming unit in the above-mentioned light signal modulating device further comprises filter circuit and integrating circuit, and described filter circuit carries out low-pass filtering to the elementary errors signal that synchronous demodulation goes out, and forms bias voltage by the integrating circuit integration then.
In the utility model, because control circuit can detect the elementary errors signal of output light, and the elementary errors signal is carried out integration form bias voltage, direct current biasing point to modulator automatically adjusts, bias point is stabilized on 1/4 periodic point (half-power point), therefore can makes the extinction ratio of output light be stabilized in maximum.Because the major function of the optic modulating device that the utility model provides is to regulate automatically the direct current biasing point of modulator, so this direct current biasing point is not necessarily to be meant half-power point, can also be the zero energy point, or other any bias points.
Description of drawings
The theory diagram of Fig. 1 light signal modulating device;
The transfer curve of Fig. 2 light signal modulating device;
Fig. 3 elementary errors signal produces schematic diagram;
Fig. 4 light signal modulating device of the present utility model system block diagram;
Fig. 5 elementary errors detection cell circuit of the present utility model figure;
Fig. 6 offset forming unit circuit diagram of the present utility model.
Embodiment
Fig. 1 is exactly a kind of external modulation schematic diagram of device that is applied to light emission module, and as shown in the figure, this external modulation device comprises optical modulator, control circuit, modulating driver and optical power distributor.Control circuit is by producing a perturbation signal and being added on the gain control end of modulating driver, make output light signal generating one low-frequency excitation, optical power distributor will be exported light and tell the luminous power of 3-5% and deliver to control circuit, produce the direct current signal of a control bias point by control circuit, thereby realize the automatic control of modulating device.
It is example that the utility model is controlled at 1/4 periodic point (half-power point) with bias point.As shown in Figure 2, promptly the direct current biasing point is stabilized on the A point of slope of curve steepest, thereby imports under the given situation of RF change in electric amplitude, obtain the output light signal of peak-peak.Its basic functional principle is the output amplitude with a low frequency perturbation signal controlling driver, input signal to modulator has added an amplitude modulation(PAM) (AM) that low frequency is faint like this, referring to Fig. 3, envelope is a low frequency perturbation signal among Fig. 3, the some A1 in A1, A2, B1, the B2 corresponding diagram 2 on the transfer curve of modulator, A2, B1, B2, as shown in Figure 2, under the corresponding bias voltage of A2 point, the Output optical power maximum, therefore in Fig. 3, its envelope signal is peak value of correspondence also.Under the situation of correct bias, the mean value of detected low frequency signal should be to keep constant in time, and shown in Fig. 3 a, light output mean value is straight line.And bias point is when departing from the A point, and average then is an error signal consistent with envelope frequency, and shown in Fig. 3 b, the light output mean value among the figure is a square wave consistent with envelope frequency.To depart from the A point far away more when bias point, and the error signal amplitude of oscillation is big more, and the changes in amplitude that is to say the error signal of generation has reflected that the modulator bias point desires the variation that control point A is ordered relatively.The bias point that error signal is carried departs from information that A orders, and we are called the elementary errors signal, and like this, error signal can be regarded elementary errors signal amplitude-modulated wave as, and its carrier frequency is with to add the perturbation signal identical.With control circuit the elementary errors signal is proposed from error signal then, and the elementary errors signal is carried out integration produce suitable biasing and feed back on the modulator bias electrode, thereby compensation work point is moved, and is zero up to the elementary errors signal, reaches the autostable purpose of bias point.
System block diagram of the present utility model as shown in Figure 4, as seen from the figure, control circuit comprises elementary errors detecting unit, synchronous demodulation unit, offset forming unit and clock source; 9.6KHz clock signal be the perturbation of modulator, also be the synchronous demodulation clock simultaneously, perturbation is modulated on the signal of telecommunication of 10Gbps with the form of amplitude modulation, add modulator by driver, continuous light is modulated, the flashlight of output separates a part as surveying light by the optical power distributor of a 3-5%, and wherein optical power distributor can be a fiber coupler.The elementary errors testing circuit will be surveyed light and convert current signal and amplification to, demodulate the elementary errors signal through the synchronous demodulation unit then, and offset forming unit carries out integration to the elementary errors signal and forms bias voltage, feeds back to the bias electrode of modulator.When the elementary errors signal was output as zero, bias voltage promptly was stabilized in 1/4 periodic point (being the A point of Fig. 1).
In the present embodiment, the synchronous demodulation unit can be the switching capacity of knowing, and the DC maladjustment amount is reduced to can be ignored.The elementary errors detecting unit then comprises testing circuit, pre-amplifying circuit and filter amplification circuit, and as shown in Figure 5, testing circuit is made up of a PIN pipe and resistance R 1, and the PIN pipe changes into the signal of telecommunication with light signal.Pre-amplifying circuit is made up of an amplifier F1, four resistance (R2, R3, R4, R5) and two electric capacity (C1, C2), and above-said current signal is amplified in advance.Deliver to filter amplification circuit then through the pre-signal of telecommunication that amplifies, carry out filtering and further the amplification, filtering mainly is the elimination interference noise, and filter amplification circuit is made up of amplifier F2, resistance R 7, R8 and capacitor C 3, C4.Filter amplification circuit in embodiment illustrated in fig. 5 is amplified for one-level filtering, as required, can also take two-stage even more multistage bandpass filtering, it is 9.6KHz that the center frequency filtering of each grade is all got the clock source frequency, multiplication factor can determine as required that present embodiment is got 20 times.Through after what filtering, interference noise etc. are removed, have obtained the amplitude-modulated wave that carries bias point elementary errors signal of abundant amplification.
The device of most critical is an operational amplifier in elementary errors detecting unit shown in Figure 5, requires to have high input impedance low maladjustment voltage, characteristics such as noise is low.First order high resistant pre-arcing road in the circuit is very important, and the amplifier of selecting for use will have low bias current, low-noise characteristic; The selection of PIN pipe load resistance R1 simultaneously will be calculated according to the thermal noise that the average light electric current that flows through produces, and recommends to select for use 1K ohm.In order to suppress AC noise, the bandpass filtering amplifying circuit adopts narrow-band filtering, is the synchronous of assurance elementary errors and reference clock simultaneously, and the Q value selection that band is logical makes the minimum that differs that accumulates on the alternating current path, and the designing gain of this circuit is 20, and the Q value is 5.Seal in filtering, amplifying circuit for fear of reference clock signal, can adopt power supply to cut apart separately, as shown in Figure 5, guarantee the tram of PIN pipe and resistance R 1 simultaneously, the PIN pipe plays the effect that insulating power supply is crosstalked like this.
The elementary errors signal that demodulates through the synchronous demodulation unit forms bias voltage through the offset forming unit integration again.Offset forming unit in the present embodiment is made up of one-level filter circuit and an integrating circuit, as shown in Figure 6.Filter circuit comprises capacitor C 5, C6 and the resistance R 9 of two ground connection, and integrating circuit comprises an amplifier F3, capacitor C 7 and two resistance R 10, R11.Illustrated filter circuit is one-level filtering, also can be set to the two-stage low-pass filtering as required, with filter away high frequency noise.Integrating circuit is to be the elementary errors conversion of signals modulator dc offset voltage.Integrating circuit needs very high sensitivity, and integration time constant is unsuitable excessive simultaneously, and it is comparatively suitable that integrating capacitor C7 elects 0.1uF as.In addition, integrating circuit determines the bandwidth of whole loop, the smaller bandwidth of control section, be no more than 1.0Hz under normal conditions, because too high loop bandwidth increases RMS (root mean square) noise at the control point, yet, when being lower than 1.0IIz, the bandwidth of loop will just can be stabilized in bias point by long time, therefore low excessively loop bandwidth responds the variation that can not effectively control bias point slowly.

Claims (4)

1, a kind of light signal modulating device that is applied in the optical communication system comprises optical modulator, control circuit, modulating driver, optical power distributor, described control circuit produces a perturbation signal and is modulated on the signal of telecommunication RF with the form of amplitude modulation, join optical modulator by modulating driver then, input light is modulated; Control circuit receives the part output light that optical power distributor is told simultaneously, feed back to modulator after therefrom detecting modulator bias point elementary errors signal, make its can be on stable bias point operate as normal, it is characterized in that: described control circuit comprises elementary errors detecting unit, synchronous demodulation unit, offset forming unit and clock source; The output light that described optical power distributor is told is after the elementary errors detecting unit changes into the signal of telecommunication and amplifies, clock synchronization in synchronous demodulation unit and the output of clock source demodulates the elementary errors signal, form bias voltage by the offset forming unit integration then modulator is carried out direct current biasing, the clock signal in described clock source also is modulated on the signal of telecommunication RF as the perturbation signal of control circuit simultaneously.
2, light signal modulating device according to claim 1, it is characterized in that: described elementary errors detecting unit further comprises testing circuit, pre-amplifying circuit and filter amplification circuit, after described detecting unit changes into the signal of telecommunication with light signal, amplify in advance by pre-amplifying circuit earlier, carry out filtering and further amplification through filter amplification circuit then.
3, light signal modulating device according to claim 1 and 2, it is characterized in that described offset forming unit further comprises filter circuit and integrating circuit, described filter circuit carries out low-pass filtering to the elementary errors signal that synchronous demodulation goes out, and forms bias voltage by the integrating circuit integration then.
4, light signal modulating device according to claim 1 and 2 is characterized in that described synchronous demodulation unit is a switching capacity.
CN 01271841 2001-11-27 2001-11-27 Optical signal modulation device of optical communication system Expired - Lifetime CN2517183Y (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN 01271841 CN2517183Y (en) 2001-11-27 2001-11-27 Optical signal modulation device of optical communication system
PCT/CN2002/000742 WO2003047143A1 (en) 2001-11-27 2002-10-22 A method and apparatus of light signal modulation in light
AU2002344522A AU2002344522A1 (en) 2001-11-27 2002-10-22 A method and apparatus of light signal modulation in light

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Application Number Priority Date Filing Date Title
CN 01271841 CN2517183Y (en) 2001-11-27 2001-11-27 Optical signal modulation device of optical communication system

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100344083C (en) * 2003-12-19 2007-10-17 青岛海信光电科技股份有限公司 Control method and control circuit of output light power and extinction ratio of light transmitter
WO2009010007A1 (en) * 2007-07-16 2009-01-22 Huawei Technologies Co., Ltd. A method, an apparatus and an optical modulator for phase adjustment
CN102164005A (en) * 2010-02-24 2011-08-24 Jds尤尼弗思公司 Bias control in an optical modulator and transmitter
WO2011100929A3 (en) * 2011-04-14 2012-03-29 华为技术有限公司 Optical modulation method and system
CN103049027A (en) * 2012-12-20 2013-04-17 浙江大学 Device and method for controlling electro-optical modulator in phase-sensitive OTDR (Optical Time Domain Reflectometer) sensor
CN107819519A (en) * 2016-09-13 2018-03-20 富士通株式会社 Measuring method, the device and system of residual DC component

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CN113472436A (en) * 2021-07-09 2021-10-01 东莞铭普光磁股份有限公司 Optical module and method for monitoring luminous power thereof

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2284243C (en) * 1991-01-10 2000-12-12 Fujitsu Limited Optical processing device operating in a wavelength-synchronized mode and an optical circuit exchanger that uses such an optical processing device
US6002513A (en) * 1998-06-22 1999-12-14 Lucent Technologies Inc. Optical modulator providing independent control of attenuation and spectral tilt
AU4264300A (en) * 1999-07-02 2001-01-11 Corning O.T.I. S.P.A. Electro-optic modulators with internal impedance matching

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100344083C (en) * 2003-12-19 2007-10-17 青岛海信光电科技股份有限公司 Control method and control circuit of output light power and extinction ratio of light transmitter
WO2009010007A1 (en) * 2007-07-16 2009-01-22 Huawei Technologies Co., Ltd. A method, an apparatus and an optical modulator for phase adjustment
CN101350674B (en) * 2007-07-16 2012-04-04 华为技术有限公司 Method and apparatus for adjusting phase as well as light modulator
CN102164005A (en) * 2010-02-24 2011-08-24 Jds尤尼弗思公司 Bias control in an optical modulator and transmitter
CN102164005B (en) * 2010-02-24 2015-08-19 Jds尤尼弗思公司 Bias voltage control in optical modulator and optical sender
WO2011100929A3 (en) * 2011-04-14 2012-03-29 华为技术有限公司 Optical modulation method and system
CN102834770A (en) * 2011-04-14 2012-12-19 华为技术有限公司 Optical modulation method and system
CN103049027A (en) * 2012-12-20 2013-04-17 浙江大学 Device and method for controlling electro-optical modulator in phase-sensitive OTDR (Optical Time Domain Reflectometer) sensor
CN107819519A (en) * 2016-09-13 2018-03-20 富士通株式会社 Measuring method, the device and system of residual DC component
CN107819519B (en) * 2016-09-13 2020-04-14 富士通株式会社 Device for measuring residual direct current component

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WO2003047143A1 (en) 2003-06-05

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Expiration termination date: 20111127

Granted publication date: 20021016