CN101630975A - Method and device for controlling bias voltage of photomodulator - Google Patents
Method and device for controlling bias voltage of photomodulator Download PDFInfo
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- CN101630975A CN101630975A CN200810132422A CN200810132422A CN101630975A CN 101630975 A CN101630975 A CN 101630975A CN 200810132422 A CN200810132422 A CN 200810132422A CN 200810132422 A CN200810132422 A CN 200810132422A CN 101630975 A CN101630975 A CN 101630975A
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Abstract
The invention discloses a method and a device for controlling bias voltage of a photomodulator and relates to the technical field of photo-communication, which solves the problem that the prior art can control the bias voltage of any point only under the condition of accurately calculating phase deviation. Before a working point drifts, the embodiment obtains the bias voltage and compensating voltage through a disturbing signal; after the working point drifts, the embodiment obtains feedback control voltage through the compensating voltage and the disturbing signal; and target bias voltage of any point is generated by the feedback control voltage and the bias voltage of any point and loaded to the photomodulator, thereby realizing the control of the bias voltage of the photomodulator. The embodiment of the invention is mainly used for adjusting the bias voltage of the photomodulator.
Description
Technical field
The present invention relates to the optical communication technique field, relate in particular to and carrying out light signal when modulation, for the method for the bias voltage control of optical modulator, and the device of realizing this method.
Background technology
Owing to be subjected to the influence of ambient temperature, the working point of optical modulator can drift about, thus the light signal generating wave distortion that makes modulation output, the wave distortion that causes in order to eliminate operating point drift, need adjust optical modulator, so that export satisfactory light signal.
On optical modulator, add earlier disturbing signal in the prior art, then the output light signal being carried out beam split detects, can measure the drift value of working point by the variation of light signal, generate a bias voltage according to the drift value of measuring, to be carried on the optical modulator after bias voltage and the modulation signal addition then, can eliminate the wave distortion that the output optical signals causes in the optical modulator operating point drift like this, described bias voltage can produce by the bias point automatic control circuit.
The bias voltage difference that optical modulator is adopted when the light signal of modulation different-format, as shown in Figure 1, abscissa is for being carried in optical modulator upper offset voltage, ordinate is the light intensity of the light signal of this bias voltage correspondence, requirement difference according to the different-format light signal, its bias voltage is also different, the bias voltage that the form that has needs is point voltage (QUAD+ point among the figure and a QUAD-point), and the bias voltage that the form that has needs is peak point voltage (the MAX point among the figure) or valley point voltage (the MIN point among the figure).
If adopt with a kind of scrambling mode, then when being detected, the output light signal need adopt different detection frequencies for different bias voltages.In order to unify to detect frequency, the scrambling mode difference that is adopted for different its disturbing signals of bias voltage, common scrambling mode comprises the property taken advantage of scrambling mode and additivity scrambling mode, the property taken advantage of scrambling mode is used for the scrambling of (comprising positive point voltage and negative point voltage) of point voltage, and additivity scrambling mode is used for the scrambling of (comprising crest voltage and valley point voltage) of peak valley point voltage.Wherein, the property taken advantage of scrambling mode is that disturbing signal is added on the gain voltage input of driver, and scrambled signals and data-signal are the relations of multiplying each other; Additivity scrambling mode is that disturbing signal is added on the bias voltage input, and scrambled signals and data-signal are the addition relations.
Present scrambling mode is that special voltages such as point voltage or peak valley point voltage carry out scrambling at bias voltage generally, and can only carry out scrambling under the situation of measuring the phase deviation of output light signal for the bias voltage of arbitrfary point.
As shown in Figure 2, be the scheme that double-parallel modulator is carried out scrambling, this scheme is carried out beam split by optical splitter to the light signal of exporting, and by detector the light signal of telling is detected, if its phase deviation can detect, can carry out the scrambling of arbitrfary point.Suppose H
xN is the detected amplitude of detected n the harmonic wave of detector, and the computing formula of the occurrence of phase deviation is:
P wherein
TxBe coupling efficiency, concrete computing formula is:
VdcR and the VdcL among the figure regulated in above-mentioned detection and the phase deviation that calculates, and then controls the bias voltage on the both arms (28R and 28L) of this double-parallel modulator, so that control the phase deviation of this double-parallel modulator.
State in realization in the scheme process, the inventor finds that there are the following problems at least in the prior art:
1, existing when controlling for the arbitrfary point bias voltage, need to detect the amplitude of harmonic wave, so that accurately calculate phase deviation, when output light signal generating carrier suppressed signal, the difficult detection of its phase deviation is also calculated, and at this time then can not carry out the control of arbitrfary point well.
2, for the situation that the difficult detection of above-mentioned phase deviation occurs and calculate, can only be that particular point voltages such as point voltage or peak valley point voltage are controlled at bias voltage.
Summary of the invention
Embodiments of the invention provide a kind of bias voltage control method and device of optical modulator, are not needing accurately to calculate under the situation of phase deviation, and the bias voltage of arbitrfary point is carried out scrambling to eliminate the wave distortion that causes because of operating point drift.
For achieving the above object, embodiments of the invention adopt following technical scheme:
A kind of bias voltage control method of optical modulator comprises:
According to calculating the bias voltage of described arbitrfary point with the immediate particular point bias voltage in arbitrfary point;
The bias voltage of disturbing signal and described arbitrfary point is carried on the optical modulator;
Obtain bucking voltage according to the error corresponding in the light signal of described optical modulator output with described disturbing signal;
When optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with described disturbing signal and described bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator;
The target bias voltage that generates described arbitrfary point by the bias voltage and the FEEDBACK CONTROL voltage of arbitrfary point, and the target bias voltage of described arbitrfary point is carried on the optical modulator.
A kind of bias voltage control device of optical modulator comprises:
Controller is used for the bias voltage that the immediate particular point bias voltage in basis and arbitrfary point calculates the arbitrfary point;
Oscillating unit is used to generate disturbing signal, and this disturbing signal is carried on the optical modulator;
Feedback control unit is used for obtaining bucking voltage according to the light signal error corresponding with described disturbing signal of described optical modulator output;
This feedback control unit also is used for when optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with described disturbing signal and bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator;
Input unit is used for the target bias voltage with the described arbitrfary point of arbitrfary point bias voltage and the generation of FEEDBACK CONTROL voltage, and the target bias voltage of described arbitrfary point is carried on the optical modulator.
A kind of optical sender comprises:
Laser module is used to produce continuous light source;
Driver module is used to import the signal of telecommunication that needs are modulated;
Optical modulator, the signal of telecommunication that is used for modulating as required is modulated into light signal with described continuous light source;
The bias voltage control device is used for the bias voltage of disturbing signal and arbitrfary point is carried in optical modulator, obtains bucking voltage according to the error corresponding with described disturbing signal in the light signal of described optical modulator output; When optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with disturbing signal and bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator; The target bias voltage of the described arbitrfary point that arbitrfary point bias voltage and FEEDBACK CONTROL voltage are generated, and the target bias voltage of described arbitrfary point is carried on the optical modulator.
The bias voltage control method and the device of the optical modulator that the embodiment of the invention provides, earlier draw optical modulator in the bucking voltage that does not take place under the operating point drift situation by disturbing signal, afterwards in the course of work, if optical modulator generation operating point drift, then produce a FEEDBACK CONTROL voltage by disturbing signal and bucking voltage, present embodiment generates new arbitrfary point target bias voltage by FEEDBACK CONTROL voltage and arbitrfary point bias voltage, and the arbitrfary point target bias voltage is carried on the optical modulator, realize control to bias voltage.Owing in the process of control bias voltage, do not need accurately to calculate phase deviation, just finish control to bias voltage by FEEDBACK CONTROL voltage, so present embodiment can be used in the situation that can not accurately calculate phase deviation, the scope of application is wider; And owing to there is FEEDBACK CONTROL voltage, so for all corresponding FEEDBACK CONTROL voltage of each arbitrfary point bias voltage, so present embodiment can realize can realizing each arbitrfary point bias voltage the control of bias voltage.
Description of drawings
Fig. 1 is the modulation waveform figure of optical modulator in the prior art;
Fig. 2 is the schematic diagram of control bias voltage in the prior art;
Fig. 3 is the flow chart of bias voltage control method in the embodiment of the invention 1;
Fig. 4 is the block diagram of bias voltage control device in the embodiment of the invention 1;
Fig. 5 is for obtaining the flow chart of initial bias voltage and bucking voltage in the embodiment of the invention 2;
Fig. 6 is the flow chart of bias voltage control method in the embodiment of the invention 2;
Fig. 7 is the block diagram of bias voltage control device in the embodiment of the invention 3;
Fig. 8 is for obtaining the theory diagram of bucking voltage in the embodiment of the invention 3;
Fig. 9 is for obtaining the theory diagram of FEEDBACK CONTROL voltage in the embodiment of the invention 3;
Figure 10 is the theory diagram of input unit in the embodiment of the invention 3.
Embodiment
Below in conjunction with accompanying drawing, the bias voltage control method and the device of embodiment of the invention optical modulator is described in detail.
Embodiment 1:
Present embodiment provides a kind of bias voltage control method of optical modulator, and as shown in Figure 3, this control method comprises the steps:
301 if control optical modulator in certain bias voltage place, arbitrfary point work, to estimate the immediate particular point bias voltage of this arbitrfary point bias voltage earlier as reference voltage, go out the arbitrfary point bias voltage according to the arbitrfary point bias voltage apart from the distance calculation of particular point bias voltage then.Particular point bias voltage wherein obtains as follows: allow optical modulator be operated on particular job point, can obtain the particular point bias voltage at input.
The arbitrfary point bias voltage that gets access in this step is exactly the bias voltage of optical modulator in this arbitrfary point, can guarantee that optical modulator can not cause the output light signal wave distortion to occur.
302, disturbing signal and arbitrfary point bias voltage are carried on the optical modulator, the optical signal frequency that the frequency of this disturbing signal generally will will be modulated far below optical modulator is to avoid that light signal is caused interference.
303, in a period of time that optical modulator has just been started working, because the conditions such as ambient temperature of optical modulator all are in initial condition, operating point drift can not take place in optical modulator, under this state, obtain bucking voltage according to the error corresponding in the light signal of described optical modulator output with described disturbing signal.
304, when making the ambient temperature of optical modulator change for a certain reason, will cause the working point of optical modulator to drift about, for example: heating causes its working temperature to change in the optical modulator course of work.After optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with described disturbing signal and bucking voltage are obtained optical modulator in the light signal according to optical modulator output, FEEDBACK CONTROL voltage wherein are to be used for eliminating operating point drift and the wave distortion of the light signal that causes.
305, generating the arbitrfary point target bias voltage by arbitrfary point bias voltage and FEEDBACK CONTROL voltage is carried on the optical modulator, the arbitrfary point target bias voltage that obtains has like this been considered the arbitrfary point bias voltage that optical modulator needs simultaneously, and the FEEDBACK CONTROL voltage that needs of the operating point drift that causes after changing of temperature, can eliminate because the optical modulator operating point drift causes wave distortion.
Bias voltage control method corresponding to above-mentioned optical modulator, the embodiment of the invention also provides a kind of bias voltage control device of optical modulator, as shown in Figure 4, this bias voltage control device comprises: oscillating unit 41, feedback control unit 42, input unit 43 and controller 44.
Wherein, controller 44 is used for calculating the arbitrfary point bias voltage according to the particular point bias voltage, is specially according to the arbitrfary point bias voltage to go out the arbitrfary point bias voltage apart from the distance calculation of particular point bias voltage; Oscillating unit 41 is used to generate disturbing signal, and this disturbing signal is carried on the optical modulator, and the function of oscillating unit 41 specifically can be passed through oscillator, oscillating circuit or crystal oscillator and realize; Optical modulator can produce corresponding light signal under the effect of disturbing signal, before optical modulator generation operating point drift, described feedback control unit 42 is used for obtaining bucking voltage according to the light signal error corresponding with described disturbing signal of described optical modulator output, the wave distortion of the light signal that causes in order to eliminate operating point drift, feedback control unit 42 in this bias voltage control device also is used for after optical modulator generation operating point drift, according to the error corresponding with described disturbing signal in the light signal of described optical modulator output, and bucking voltage is obtained the FEEDBACK CONTROL voltage of optical modulator; Described input unit 43 is used for arbitrfary point bias voltage and FEEDBACK CONTROL voltage generation arbitrfary point target bias voltage are carried in optical modulator, the operating point drift that causes after if the ambient temperature of optical modulator changes, act on simultaneously on the optical modulator by arbitrfary point bias voltage and FEEDBACK CONTROL voltage, can eliminate because the optical modulator operating point drift causes wave distortion.
Bias voltage control device, laser module, drive circuit and optical modulator by above-mentioned optical modulator can constitute an optical sender jointly, wherein laser module is used to produce continuous light source, drive circuit is used to import the signal of telecommunication of needs modulation, after the bias voltage control device is loaded into optical modulator with bias voltage, the signal of telecommunication that this optical modulator can be modulated as required is modulated into light signal with continuous light source, the optical parameter feature of this light signal and the parameter attribute correspondence of the described signal of telecommunication.
The bias voltage that above-mentioned bias voltage control device also needs to be used for disturbing signal and arbitrfary point is carried in optical modulator, obtains bucking voltage according to the error corresponding with described disturbing signal in the light signal of described optical modulator output; When optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with disturbing signal and bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator; The target bias voltage of the described arbitrfary point that arbitrfary point bias voltage and FEEDBACK CONTROL voltage are generated, and the target bias voltage of described arbitrfary point is carried on the optical modulator.
Because present embodiment does not need accurately to calculate phase deviation in the process of control bias voltage, just finish control to bias voltage by FEEDBACK CONTROL voltage, so present embodiment can be used in the situation that can not accurately calculate phase deviation, the scope of application is wider; And owing to there is FEEDBACK CONTROL voltage, so for all corresponding FEEDBACK CONTROL voltage of arbitrfary point bias voltage, so present embodiment can realize can realizing the bias voltage of arbitrfary point the control of bias voltage.
Embodiment 2:
Present embodiment provides a kind of bias voltage control method of optical modulator, in order to control bias voltage easily, need obtain optical modulator does not earlier have the arbitrfary point bias voltage in when drift in the working point, and the bucking voltage that needs during bias voltage of control, the described process of obtaining arbitrfary point bias voltage and bucking voltage specifically comprises the steps: as shown in Figure 5
501 if control optical modulator in certain bias voltage place, arbitrfary point work, to estimate the immediate particular point bias voltage of this arbitrfary point bias voltage earlier as reference voltage, go out the arbitrfary point bias voltage according to the arbitrfary point bias voltage apart from the distance calculation of particular point bias voltage then.Particular point bias voltage wherein obtains as follows: allow optical modulator be operated on particular job point, can obtain the particular point bias voltage at input.
The arbitrfary point bias voltage that gets access in this step is exactly the bias voltage of optical modulator, can guarantee that optical modulator can not cause the output light signal wave distortion to occur.
502, disturbing signal is carried on the optical modulator, the optical signal frequency that the frequency of this disturbing signal generally will will be modulated far below optical modulator is to avoid that light signal is caused interference.
When specifically loading disturbing signal, need treat with a certain discrimination according to the difference of bias voltage, if the bias voltage that is adopted of optical modulator is the peak valley point voltage, then disturbing signal is carried in the bias voltage input of optical modulator; If the bias voltage that is adopted of optical modulator is a point voltage, then disturbing signal is carried in the driver gain control end of optical modulator.
503, before optical modulator generation operating point drift, the light signal that light modulator modulates is gone out changes into ac signal, generally is that the output light signal is told a branch of light signal by optical splitter, so that be used for changing into ac signal.
504, because the optical signal frequency that the frequency of disturbing signal will be modulated far below optical modulator can carry out filtering to described ac signal by filter, to obtain the ac signal corresponding with the disturbing signal frequency.
505, the ac signal that filtering is obtained carries out bit comparison mutually with disturbing signal and draws phase signal, and this phase signal can be expressed the operating point drift direction and the size of optical modulator.
506, described phase signal is changed into dc signal.
507, set a predetermined voltage.
508, judge whether described predetermined voltage and described dc signal addition result are zero; If addition result is zero, then execution in step 509; Otherwise return step 507.
509, bucking voltage is taken as described predetermined voltage.
Obtained arbitrfary point bias voltage and bucking voltage by the flow process among Fig. 5, the arbitrfary point bias voltage need be loaded into optical modulator when specifically the bias voltage of optical modulator being controlled, as shown in Figure 6, the concrete steps of this control method are as follows:
601, disturbing signal is carried on the optical modulator, the optical signal frequency that the frequency of this disturbing signal generally will will be modulated far below optical modulator is to avoid that light signal is caused interference.
When specifically loading disturbing signal, need treat with a certain discrimination according to the reference voltage difference of bias voltage, if the reference voltage of the bias voltage that is adopted of optical modulator is the peak valley point voltage, then disturbing signal is carried in the bias voltage input of optical modulator; If the reference voltage of the bias voltage that is adopted of optical modulator is a point voltage, then disturbing signal is carried in the driver gain control end of optical modulator.
602, after optical modulator generation operating point drift, the light signal that light modulator modulates is gone out changes into ac signal, arbitrfary point bias voltage process is the same with obtaining, and generally will export light signal in this step and tell a branch of light signal by optical splitter, so that be used for changing into ac signal.
603, because the optical signal frequency that the frequency of disturbing signal will be modulated far below optical modulator can carry out filtering to described ac signal by filter, to obtain the ac signal corresponding with the disturbing signal frequency.
604, the ac signal that filtering is obtained carries out bit comparison mutually with disturbing signal and draws phase signal, and this phase signal can be expressed the operating point drift direction and the size of optical modulator.
605, change into dc signal with drawing phase signal in the step 604.
606,, and the voltage after the addition carried out integration draw FEEDBACK CONTROL voltage with described dc signal and bucking voltage addition, this FEEDBACK CONTROL voltage response the wave distortion that produces owing to variation of temperature of optical modulator.
607, with being loaded on the optical modulator after above-mentioned FEEDBACK CONTROL voltage and the arbitrfary point bias voltage generation arbitrfary point target bias voltage, just can eliminate the wave distortion that optical modulator occurs behind operating point drift.
Because forward bias and negative sense biasing may appear in the wave distortion that optical modulator occurs, have only the FEEDBACK CONTROL polarity of voltage correctly could eliminate the phase deviation that optical modulator produces owing to variation of temperature, if polarity is opposite, the phase deviation that may cause optical modulator to produce is more serious.So, when present embodiment is positive point voltage or crest voltage at the reference voltage of optical modulator arbitrfary point bias voltage, arbitrfary point bias voltage and the addition of FEEDBACK CONTROL voltage are carried on the optical modulator as the arbitrfary point target bias voltage; At the reference voltage of optical modulator arbitrfary point bias voltage during, arbitrfary point bias voltage and FEEDBACK CONTROL voltage subtracted each other as the arbitrfary point target bias voltage be carried on the optical modulator for negative point voltage or valley point voltage.
Present embodiment can be suitable for for the bias voltage of arbitrfary point, only need determine the approaching special bias voltage of this bias voltage before using present embodiment, as: point voltage or peak valley point voltage.If this arbitrfary point bias voltage more near point voltage, then is carried in disturbing signal the driver gain control end of optical modulator, promptly adopt the property taken advantage of scrambling mode; If this arbitrfary point bias voltage more near the peak valley point voltage, then is carried in disturbing signal the bias voltage input of optical modulator, promptly adopt additivity scrambling mode.
Embodiment 3:
Corresponding to the foregoing description 2, present embodiment provides a kind of bias voltage control device of optical modulator, and as shown in Figure 7, this bias voltage control device comprises: oscillating unit 71, selected cell 72, feedback control unit 73, input unit 74 and controller 75.
Wherein, controller 75 is used for calculating the arbitrfary point bias voltage according to the particular point bias voltage, can calculate the arbitrfary point bias voltage according to the arbitrfary point bias voltage apart from the distance of particular point bias voltage; Oscillating unit 71 is used to generate disturbing signal, and this disturbing signal is carried on the optical modulator, and the function of oscillating unit 71 specifically can be passed through oscillator, oscillating circuit or crystal oscillator and realize; The disturbing signal selection that selected cell 72 is used for that oscillating unit 71 is generated is carried in the bias voltage input of optical modulator, perhaps be carried in the driver gain control end of optical modulator, this selected cell 72 can be realized by the electronic switch of a single input dual output.
Optical modulator can produce corresponding light signal under the effect of above-mentioned disturbing signal, before optical modulator generation operating point drift, described feedback control unit 73 is used for obtaining according to described disturbing signal the arbitrfary point bias voltage of optical modulator, and obtain bucking voltage, specifically: under the effect of disturbing signal, produce the corresponding light signal from optical modulator and can get access to described bucking voltage; The phase deviation of the light signal that causes in order to eliminate operating point drift, feedback control unit 73 in this bias voltage control device also is used for after optical modulator generation operating point drift, obtains the FEEDBACK CONTROL voltage of optical modulator according to described disturbing signal and bucking voltage; Described input unit 74 is used for arbitrfary point bias voltage and FEEDBACK CONTROL voltage are carried in optical modulator as the arbitrfary point target bias voltage together, the operating point drift that causes after if the ambient temperature of optical modulator changes, act on simultaneously on the optical modulator by arbitrfary point bias voltage and FEEDBACK CONTROL voltage, can eliminate because the optical modulator operating point drift causes phase deviation.
As shown in Figure 7, feedback control unit 73 in the present embodiment mainly comprises following device: optical-electrical converter 731, band pass filter 732, synchronizing indicator 733 and low pass filter 734, can get access to the arbitrfary point bias voltage by these devices and controller 75, concrete operation principle is described below:
At first on optical modulator, load an initial bias voltage, optical-electrical converter 731 was used for before optical modulator generation operating point drift, the light signal that light modulator modulates is gone out changes into ac signal, generally speaking, the light signal that is input to optical-electrical converter 731 is the light signal of telling by optical splitter.Band pass filter 732 is used for that described ac signal is carried out filtering and obtains the ac signal corresponding with the disturbing signal frequency, and the passband of this band pass filter 732 need be corresponding with the disturbing signal frequency.The ac signal that synchronizing indicator 733 is used for filtering is obtained carries out bit comparison mutually with disturbing signal, and the output phase difference signal.Low pass filter 734 is used for described phase signal is changed into dc signal, this direct current signal can obtain the particular point feedback voltage through after the integration, this particular point feedback voltage adds that initial bias voltage is exactly the particular point bias voltage, has controller 75 to calculate the arbitrfary point bias voltage according to the arbitrfary point bias voltage apart from the distance of particular point bias voltage then.
In order to guarantee that signal strength signal intensity is enough big, can between optical-electrical converter 731 and band pass filter 732, amplifier 738 be set, light signal is changed into ac signal amplify
Present embodiment need obtain bucking voltage by the feedback control module in the feedback control unit 73 739, and as shown in Figure 8, the feedback control module 739 in the present embodiment comprises: variable voltage source 735, adder 736.
Described variable voltage source 735 is used to export predetermined voltage; Adder 736 is used for predetermined voltage and described low pass filter 734 output DC signal plus; The addition result of these adder 736 outputs is directly controlled variable voltage source 735, and when the addition result of adder 736 outputs was zero, variable voltage source 735 also was used for described predetermined voltage is output as bucking voltage, can obtain bucking voltage.
After obtaining bucking voltage and arbitrfary point bias voltage, can control the bias voltage of described optical modulator, that is: get access to FEEDBACK CONTROL voltage by feedback control unit 73 after, can realize control to bias voltage, feedback control unit 73 in the present embodiment obtains FEEDBACK CONTROL voltage by feedback control module 739, as shown in Figure 9, when needs obtain FEEDBACK CONTROL voltage, feedback control module 739 also comprises adder 737 and integrator 740, and the dc signal of low pass filter 734 no longer outputs to adder 736, but output to adder 737, the specific descriptions of specifically obtaining FEEDBACK CONTROL voltage are as follows:
Optical-electrical converter 731 is used for after optical modulator generation operating point drift, and the light signal that light modulator modulates is gone out changes into ac signal, and the light signal that is input to optical-electrical converter 731 is the light signal of telling by optical splitter.Band pass filter 732 is used for that described ac signal is carried out filtering and obtains the ac signal corresponding with the disturbing signal frequency, and the band connection frequency of this band pass filter 732 is corresponding with the disturbing signal frequency.The ac signal that synchronizing indicator 733 is used for filtering is obtained carries out bit comparison mutually with disturbing signal, and the output phase difference signal.Low pass filter 734 is used for described phase signal is changed into dc signal, adder 737 is used for the bucking voltage addition with described dc signal and variable voltage source 735 outputs, then voltage after the addition is drawn FEEDBACK CONTROL voltage by integrator 740 integrations.
If above-mentioned FEEDBACK CONTROL voltage and arbitrfary point bias voltage are loaded on the optical modulator together, just can eliminate the wave distortion that optical modulator occurs behind operating point drift.Because forward bias and negative sense biasing may appear in the wave distortion that optical modulator occurs, for the polarity that guarantees to import FEEDBACK CONTROL voltage is correct, as shown in figure 10, described input unit 74 comprises control switch 741 and adder 742.
Described control switch 741 is used for FEEDBACK CONTROL voltage being carried in the positive input of described adder 742 when the reference voltage of optical modulator arbitrfary point bias voltage is positive point voltage or crest voltage; When the reference voltage of optical modulator arbitrfary point bias voltage is negative point voltage or valley point voltage, FEEDBACK CONTROL voltage is carried in the reverse input end of described adder 742; Described arbitrfary point bias voltage is carried in the positive input 742 of described adder.The voltage of the output of described adder 742 after with computing outputs to the input of optical modulator.Present embodiment guarantees that by the input difference of FEEDBACK CONTROL voltage input summer 742 under different situations the polarity of input FEEDBACK CONTROL voltage is correct.
Above-mentioned positive point voltage, crest voltage, negative point voltage and valley point voltage particular location are seen Fig. 1, the abscissa that MAX point among Fig. 1 is corresponding is a crest voltage, the abscissa that the MIN point is corresponding is a valley point voltage, the abscissa that the QUAD+ point is corresponding is positive point voltage, and the abscissa that the QUAD-point is corresponding is negative point voltage.
When present embodiment specifically uses, if the bias voltage that optical modulator adopts is an arbitrfary point voltage, at first the bias voltage with optical modulator is arranged on and the immediate particular point voltage of arbitrfary point voltage (comprising: MAX point, MIN point, QUAD+ point and QUAD+ point), draws the arbitrfary point bias voltage and the bucking voltage of output this moment; Disconnect the dc signal that is input to adder 736 then, directly the bucking voltage with variable voltage source 735 outputs is input to adder 737, and dc signal source is input to adder 737, can obtain FEEDBACK CONTROL voltage.Above-mentioned FEEDBACK CONTROL voltage and arbitrfary point bias voltage are input to optical modulator by input unit, have promptly eliminated wave distortion optical modulator output light signal.
The embodiment of the invention is mainly used in to be adjusted the bias voltage of optical modulator, after the working point of optical modulator drifts about when special, the bias voltage of arbitrfary point is adjusted control.
The above; only be the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion by described protection range with claim.
Claims (13)
1, a kind of bias voltage control method of optical modulator is characterized in that, comprising:
According to calculating the bias voltage of described arbitrfary point with the immediate particular point bias voltage in arbitrfary point;
The bias voltage of disturbing signal and described arbitrfary point is carried on the optical modulator;
Obtain bucking voltage according to the error corresponding in the light signal of described optical modulator output with described disturbing signal;
When optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with described disturbing signal and described bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator;
The target bias voltage that generates described arbitrfary point by the bias voltage and the FEEDBACK CONTROL voltage of arbitrfary point, and the target bias voltage of described arbitrfary point is carried on the optical modulator.
2, the bias voltage control method of optical modulator according to claim 1 is characterized in that, described disturbing signal is carried in the bias voltage input of optical modulator, and perhaps described disturbing signal is carried in the driver gain control end of optical modulator.
3, the bias voltage control method of optical modulator according to claim 1 is characterized in that, obtains bucking voltage according to the error corresponding with described disturbing signal in the light signal of described optical modulator output and comprises:
The light signal that light modulator modulates is gone out changes into ac signal;
Described ac signal is carried out filtering obtain the ac signal corresponding with the disturbing signal frequency;
The ac signal that filtering is obtained carries out bit comparison mutually with disturbing signal and draws phase signal;
Described phase signal is changed into dc signal;
Set predetermined voltage;
With predetermined voltage and described dc signal addition;
If described addition result is zero, bucking voltage is taken as described predetermined voltage.
4, the bias voltage control method of optical modulator according to claim 3, it is characterized in that, also comprise: if described addition result is non-vanishing, then reset predetermined voltage, and when the predetermined voltage that resets and described dc signal add up to zero, bucking voltage is taken as the predetermined voltage that resets.
5, the bias voltage control method of optical modulator according to claim 3, it is characterized in that the FEEDBACK CONTROL voltage that error corresponding with described disturbing signal and described bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator comprises:
When optical modulator generation operating point drift, the light signal that light modulator modulates is gone out changes into ac signal;
Described ac signal is carried out filtering to be obtained and the ac signal corresponding with the disturbing signal frequency;
The ac signal that filtering is obtained carries out bit comparison mutually with disturbing signal and draws phase signal;
Described phase signal is changed into dc signal;
With described dc signal and bucking voltage addition;
Voltage integrating meter after the addition is drawn FEEDBACK CONTROL voltage.
6, the bias voltage control method of optical modulator according to claim 1, it is characterized in that, the target bias voltage that generates described arbitrfary point by the bias voltage and the FEEDBACK CONTROL voltage of arbitrfary point, and the target bias voltage of described arbitrfary point is carried on the optical modulator is:
When being positive point voltage or crest voltage, the bias voltage of arbitrfary point and the addition of the FEEDBACK CONTROL voltage target bias voltage as described arbitrfary point is carried on the optical modulator with the immediate particular point bias voltage in described arbitrfary point;
When with the immediate particular point bias voltage in described arbitrfary point during for negative point voltage or valley point voltage, the target bias voltage that the bias voltage and the FEEDBACK CONTROL voltage of arbitrfary point is subtracted each other as described arbitrfary point is carried on the optical modulator.
7, according to the bias voltage control method of any described optical modulator in the claim 1 to 6, it is characterized in that the optical signal frequency that the frequency of described disturbing signal need be modulated far below optical modulator.
8, a kind of bias voltage control device of optical modulator is characterized in that, comprising:
Controller is used for the bias voltage that the immediate particular point bias voltage in basis and arbitrfary point calculates the arbitrfary point;
Oscillating unit is used to generate disturbing signal, and this disturbing signal is carried on the optical modulator;
Feedback control unit is used for obtaining bucking voltage according to the light signal error corresponding with described disturbing signal of described optical modulator output;
This feedback control unit also is used for when optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with described disturbing signal and bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator;
Input unit is used for the target bias voltage with the described arbitrfary point of arbitrfary point bias voltage and the generation of FEEDBACK CONTROL voltage, and the target bias voltage of described arbitrfary point is carried on the optical modulator.
9, the bias voltage control device of optical modulator according to claim 8 is characterized in that, also comprises:
Selected cell, the disturbing signal that is used for that oscillating unit is generated selects to be carried in the input of input unit, perhaps is carried in the driver gain control end of optical modulator.
10, the bias voltage control device of optical modulator according to claim 8 is characterized in that, described feedback control unit comprises:
Optical-electrical converter is used for the light signal that light modulator modulates goes out is changed into ac signal;
Band pass filter is used for that described ac signal is carried out filtering and obtains the ac signal corresponding with the disturbing signal frequency;
Synchronizing indicator, the ac signal that is used for filtering is obtained carries out bit comparison mutually with disturbing signal, and the output phase difference signal;
Low pass filter is used for described phase signal is changed into dc signal;
Variable voltage source is used to export predetermined voltage;
Adder is used for predetermined voltage and described dc signal addition;
Described variable voltage source also is used for when described addition result is zero described predetermined voltage being output as bucking voltage.
11, the bias voltage control device of optical modulator according to claim 10 is characterized in that,
Described optical-electrical converter also is used for when optical modulator generation operating point drift, and the light signal that light modulator modulates is gone out changes into ac signal;
Described band pass filter is used for that also described ac signal is carried out filtering and obtains the ac signal corresponding with the disturbing signal frequency;
The ac signal that described synchronizing indicator is used for that also filtering is obtained carries out bit comparison mutually with disturbing signal and draws phase signal;
Described low pass filter also is used for described phase signal is changed into dc signal;
Described feedback control unit also comprises:
Adder is used for described dc signal and bucking voltage addition;
Integrator is used for the voltage integrating meter after the addition is drawn FEEDBACK CONTROL voltage.
12, the bias voltage control device of optical modulator according to claim 8 is characterized in that, described input unit comprises control switch and adder, and the output of described adder is connected to the bias voltage input of optical modulator;
Described control switch is used for FEEDBACK CONTROL voltage being carried in the positive input of described adder when being positive point voltage or crest voltage with the immediate particular point bias voltage in described arbitrfary point; When being negative point voltage or valley point voltage, FEEDBACK CONTROL voltage is carried in the reverse input end of described adder with the immediate particular point bias voltage in described arbitrfary point;
Described arbitrfary point bias voltage is carried in the positive input of described adder.
13, a kind of optical sender is characterized in that, comprising:
Laser module is used to produce continuous light source;
Driver module is used to import the signal of telecommunication that needs are modulated;
Optical modulator, the signal of telecommunication that is used for modulating as required is modulated into light signal with described continuous light source;
The bias voltage control device is used for the bias voltage of disturbing signal and arbitrfary point is carried in optical modulator, obtains bucking voltage according to the error corresponding with described disturbing signal in the light signal of described optical modulator output; When optical modulator generation operating point drift, the FEEDBACK CONTROL voltage that error corresponding with disturbing signal and bucking voltage are obtained optical modulator in the light signal according to the output of described optical modulator; The target bias voltage of the described arbitrfary point that arbitrfary point bias voltage and FEEDBACK CONTROL voltage are generated, and the target bias voltage of described arbitrfary point is carried on the optical modulator.
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