CN101276067A - Dynamic control method and device of lithium niobate modulator - Google Patents
Dynamic control method and device of lithium niobate modulator Download PDFInfo
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- CN101276067A CN101276067A CNA2008100972313A CN200810097231A CN101276067A CN 101276067 A CN101276067 A CN 101276067A CN A2008100972313 A CNA2008100972313 A CN A2008100972313A CN 200810097231 A CN200810097231 A CN 200810097231A CN 101276067 A CN101276067 A CN 101276067A
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Abstract
The present invention provides a dynamic control device of a lithium niobate modulator and a method thereof. The device comprises a modulation signal generating module, an error processing module, a bias point and modulation range control module, wherein, the modulation signal generating module is used for generating a low-frequency signal for applying and a demodulating signal for demodulating. The error processing module is used for executing filter amplifying to the modulator output detection signal which is applied with the low-frequency signal, and obtaining the error information through the signal relationship analysis. The bias point and modulation range control module is used for applying the low-frequency signal to this signal to be controlled or the other signal to be controlled, and regulating this signal to be controlled according to the error information, wherein the signal to be controlled is the bias point signal or a modulation range signal. The method and device according to the invention execute a feedback control to the bias voltage and modulation range of the lithium niobate modulator, and greatly increases the control precision to the modulation state of the lithium niobate modulator.
Description
Technical field
The present invention relates to the dynamic control in the laser instrument external modulation technology of wavelength-division field, especially a kind of lithium niobate LiNbO
3The method and apparatus of the dynamic control of modulator.
Background technology
For the optical transmission system of two-forty, long distance, must adopt the mode of external modulation to laser instrument, especially adopt LiNbO
3Modulator carries out the mode of external modulation, owing to have two-forty, big extinction ratio, big luminous power, warble adjustable and to advantages such as wavelength are insensitive, becomes at a high speed long system of distance in the first-selection of many applied environment modulated modes, but owing to LiNbO
3The bias point position of modulator can produce drift along with the influence of factors such as temperature change and device aging, and modulation voltage is added in and on the bias point light is modulated, therefore, the drift of bias point must influence the performance of modulation output light, and this just requires using LiNbO
3Must be during the external modulation mode to LiNbO
3Modulator provides adaptive biasing control.
At present existing about LiNbO
3The patent of modulator bias point control aspect all is at LiNbO
3This parameter of modulator bias voltage carries out FEEDBACK CONTROL, but the variation of modulation amplitude also can have influence on the control of modulation effect and bias point position, therefore, realize, need carry out FEEDBACK CONTROL simultaneously bias point position and modulation amplitude to the more accurate monitoring of modulation condition.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of device for controlling dynamically and method of lithium niobate modulator, realizes LiNbO simultaneously bias point and modulation amplitude are carried out FEEDBACK CONTROL
3The more accurate monitoring of modulators modulate state.
In order to address the above problem, the invention provides a kind of device for controlling dynamically of lithium niobate modulator, this device is by loading the control of low frequency signal realization to bias point and modulation amplitude, this device comprises modulation signal generation module, Error processing module and bias point and modulation amplitude control module, wherein
Modulation signal generation module is used to produce the low frequency signal that loads usefulness and conciliates the restituted signal that calls;
The Error processing module is used for that the modulator output detection signal that is loaded with low frequency signal is carried out filtering amplifies, and analyzes acquisition control information by signal correction;
Bias point and modulation amplitude control module are used for to this signal to be controlled or another signal loading low frequency signal to be controlled, and are used for according to control information this signal to be controlled being adjusted, and signal wherein to be controlled is meant bias point signal or modulation amplitude signal.
Further, described Error processing module comprises photodetector, amplifier, wave filter and detuner, and the output detection signal of modulator is output error signal behind amplifier, wave filter, detuner, and another input signal of quadrature demodulator is a restituted signal.
Further, described Error processing module also comprises the Error processing unit, is used for the error signal of modulator output is carried out different linear or non-linear adjustment, adjusts signal to obtain error, realizes the control to bias point or modulation amplitude.
Further, this device also comprises a timing control module, is used to produce two timing controling signals, to realize the control to bias point and modulation amplitude at times.
Further, described restituted signal, low frequency signal and two timing controling signals are the signals that come from same clock source, wherein restituted signal is a clock signal, low frequency signal is this synchronization of clock signals sinusoidal signal, two timing controling signal phase places are opposite, are the homophase n fractional frequency signals of clock signal.
Further, bias point and modulation amplitude control module realize control by the mode that bias point and modulation amplitude add modulation signal mutually, this module comprises the first, second, third and the 4th totalizer (41,42,43,44), first, second switch (45,46) of first timing controling signal control, the the 3rd, the 4th switch (47,48) and the signal driver of the control of second timing controling signal, wherein
Error is adjusted the first input end of signal through first switch (45) input first adder (41), first input end through the 3rd switch (47) input second adder (42), second input end of the modulation amplitude value of setting input first adder (41), second input end of the signal biasing value of setting input second adder (42), it all is direct current signal that error is adjusted signal and signal biasing value of setting and the signal amplitude value of setting, and it all is direct current signal that error is adjusted signal, signal biasing value of setting and the signal amplitude value of setting; Before adjusting beginning, signal biasing value of setting and the signal amplitude value of setting provide an initial value earlier, adjust the signal respective change with error afterwards;
Low frequency signal is through the first input end of second switch (46) input the 3rd totalizer (43), the output signal of second adder (42) is imported second input end of the 3rd totalizer (43), the bias voltage input end of the output signal input lithium niobate modulator of the 3rd totalizer (43);
Low frequency signal is through the first input end of the 4th switch (48) input the 4th totalizer (44), the output signal of first adder (41) is imported second input end of the 4th totalizer (44), the gain control pin of the output signal input signal driver of the 4th totalizer 44, the output signal input high-frequency signal input end of signal driver.
Further, bias point and modulation amplitude control module realize control, described first switch in this module and described the 3rd position of the switch intermodulation by bias point and modulation amplitude from the mode that adds modulation signal.
For solving the problems of the technologies described above, the present invention also provides a kind of kinetic controlling equation method of lithium niobate modulator, and this method is by loading the control of low frequency signal realization to bias point and modulation amplitude, and the control method of this each signal to be controlled may further comprise the steps:
A: input modulator behind superposition one low frequency signal on this signal to be controlled or another signal to be controlled;
B: the modulator output detection signal is carried out filtering amplification, demodulation obtain error and adjust signal;
C: adjust signal according to this error and adjust the control of this signal realization to be controlled to this signal to be controlled, described signal to be controlled refers to bias point signal or modulation amplitude signal.
Further, at times bias point or modulation amplitude are realized control.
Further, adopt the at times control of two clock control signals realizations to bias point and modulation amplitude, low frequency signal described in the steps A is a sinusoidal signal, after among the step B modulator output detection signal being carried out filtering and amplifies, utilize with this low frequency signal clock signal synchronous and carry out demodulation, and described two timing controling signal phase places are opposite, and come from same clock source with clock signal, are the homophase n fractional frequency signals of clock signal.
The inventive method and device are to lithium niobate (LiNbO
3) modulator bias voltage and modulation amplitude carried out FEEDBACK CONTROL simultaneously, improved LiNbO greatly
3The control accuracy of modulators modulate state has reduced because the possibility that the variation of modulation amplitude causes modulating performance to descend has been improved LiNbO
3The reliability of modulator work has effectively improved LiNbO
3The stability of modulator work.
Description of drawings
Fig. 1 is the device for controlling dynamically block diagram of lithium niobate modulator of the present invention.
Fig. 2 is the dynamic control principle synoptic diagram of lithium niobate modulator of the present invention.
When Fig. 3 is the parameter intermodulation to modulation amplitude V
RFThe principle of controlling, (a) and (b), (c) are respectively to should modulation signal V among Fig. 3
RFAmplitude equal V
π, greater than V
π, less than V
πThe time modulation case.
Fig. 4 is the structured flowchart of the control device of embodiment 1, wherein realizes dynamically control by the parameter intermodulation.
Fig. 5 is signal Tone, S0, S1 and control signal V
Add, V
AMBetween timing diagram.
Fig. 6 is that parameter is exchanged system amplitude V from timing
RFThe principle of controlling, (a) and (b), (c) are respectively to should modulation signal V among Fig. 6
RFAmplitude equal 2V
π, greater than 2V
π, less than 2V
πThe time modulation case.
Fig. 7 is the control device structured flowchart of embodiment 2, wherein realizes dynamically control by parameter self-regulated.
Embodiment
Lithium niobate LiNbO of the present invention
3The device for controlling dynamically of modulator as shown in Figure 1, is used for bias point signal and modulation amplitude signal are controlled, and this device comprises: modulation signal generation module, Error processing module, bias point and modulation amplitude control module and timing control module, wherein:
Modulation signal generation module is used to produce the low frequency signal that loads usefulness and conciliates the restituted signal that calls;
The Error processing module is used for the modulator output detection signal that is loaded with low frequency signal is carried out the filtering amplification and analyzes acquisition error adjustment signal by signal correction;
Bias point and modulation amplitude control module are used for to this signal to be controlled or another signal loading low frequency signal to be controlled, and be used for according to error adjustment signal this signal to be controlled being adjusted, signal wherein to be controlled is bias point signal or modulation amplitude signal.
Timing control module is responsible for producing timing signal, to realize the control to bias point signal and modulation amplitude signal at times.
Because bias point and modulation amplitude all can exert an influence to modulation condition, must guarantee that to these two parameter control are quadratures when therefore when realizing, controlling to two parameters, the method that realizes includes the control signal that adopts different frequency, or in time multiplexing of same control signal.Because to LiNbO
3Modulator, adopt the method for frequency orthogonal to carry out to make feedback control system very complicated simultaneously to the control of bias point position and modulation amplitude, consider that simultaneously the drift of bias point position or the variation of modulation amplitude all are gradual processes, therefore emphasis is considered control method that bias point position and modulation amplitude timesharing are carried out among the present invention, not only can realize more accurate control, and can reduce the complexity of system greatly modulation condition.Because this scheme need periodically be switched between the control to bias point position and modulation amplitude, so the control corresponding system need increase the timing controlled part.
On the specific implementation method, to control with low frequency signal of superposition, control signal both can be carried on the signal that will control, also can be carried on the other signal.As shown in Figure 2, gain signal V wherein
GainThe gain control pin of input signal driver has determined the enlargement factor of signal driver, promptly with High Speed Modulation signal V
RFAmplitude positive correlation, V
GainV greatly then
RFAmplitude big, vice versa.Vb is a direct current level, is the setting value of bias point signal Vbias.
The scheme that two parameters add modulation signal mutually is promptly: 1, will control bias point signal V
Bias, then at gain signal V
GainLow frequency signal V of last superposition
AM, as bias point signal V
BiasWhen different directions was offset, the low frequency signal of superposition can have different performances on the light signal that modulates, and adjusted biasing voltage signal Vb according to the difference that shows on the output light signal, guaranteed bias point signal V
BiasBe operated in desired value; 2, to control modulation signal V
RFAmplitude, then at biasing voltage signal V
bLow frequency signal V of last superposition
Add, when the amplitude of VRF was bigger than normal or less than normal, the low frequency signal of superposition can have different performances on the light signal that modulates, and adjusted gain signal Vgain according to the difference of output light signal performance, and the amplitude that promptly guarantees modulation signal VRF is in desired value.
Two parameters are from the scheme of tonal signal promptly: 1, will control Vbias, then low frequency signal V of superposition on Vb
Add, work as V
BiasWhen different directions was offset, the low frequency signal of superposition can have different performances on the light signal that modulates, and adjusted V according to the difference that shows on the output light signal
b, guarantee V
BiasBe operated in desired value; 2, to control V
RFAmplitude, then at V
GainLow frequency signal V of last superposition
AM, work as V
RFAmplitude when bigger than normal or less than normal, the low frequency signal of superposition can have different performances on the light signal that modulates, adjust V according to the difference of output light signal performance
Gain, can guarantee modulation signal V
RFAmplitude be controlled in desired value.
Realize at times bias point and modulation amplitude are controlled with same low frequency signal, realize this two different control procedures, the position difference that same modulation signal loaded in the different periods, the post-processed of signal are also different.Below in conjunction with accompanying drawing these two kinds of control methods are elaborated for example.
What embodiment 1 provided is by two parameters being added mutually a kind of scheme of modulation signal realization to the control of this parameter, i.e. control to bias voltage realizes by load low frequency signal on modulation amplitude, and the control of modulation amplitude is realized that by load low frequency signal on bias voltage target is with modulation signal V
RFAmplitude be controlled at V
π, with bias point voltage V
BiasBe controlled at V
Bias=V
π/ 2.
To bias point voltage V
BiasControl method with at present existing other patent principles are identical, by to modulation signal V
RFThe method of last loading low frequency signal modulation realizes;
To modulation signal V
RFAmplitude control adopt and V
BiasThe similar principle of control method, by to bias point voltage V
BiasThe method of last loading low frequency signal modulation realizes.Fig. 3 has provided modulation signal V
RFThe principle controlled of amplitude, (a) and (b), (c) corresponding V respectively among Fig. 3
RFAmplitude equal V
π, greater than V
π, less than V
πThe time modulation case:
What Fig. 3 (a) provided is as modulation signal V
RFAmplitude equal V
π, at V
Bias=V
πThe superposition frequency is f on/2 the basis
0Low frequency signal the time modulation case, can see because V
RFAmplitude equal V
π, " 1 " signal and " 0 " signal are modulated near the crest of adjustment curve and trough respectively, and the signal after obtaining modulating is f with frequency
0Low frequency superposition signal to be converted into frequency be 2f
0The low frequency amplitude modulation(PAM), and High Speed Modulation signal V can appear
RFFrequency-doubled signal.
What Fig. 3 (b) provided is as modulation signal V
RFAmplitude greater than V
π, at V
Bias=V
πThe superposition frequency is f on/2 the basis
0Modulation case during low frequency signal can be seen because V
RFAmplitude greater than V
π, " 1 " signal and " 0 " signal are modulated on another edge of the crest of crossing adjustment curve and trough respectively, and it is f that the signal after obtaining modulating comprises frequency
0Low frequency signal and and V
BiasThe frequency of last superposition is f
0Low frequency signal phase place phase difference of pi, and High Speed Modulation signal V can appear
RFFrequency-doubled signal.
What Fig. 3 (c) provided is as modulation signal V
RFAmplitude less than V
π, at v
Bias=V
πThe superposition frequency is f on/2 the basis
0Modulation case during low frequency signal can be seen because V
RFAmplitude less than V
π, " 1 " signal and " 0 " signal are all at V
BiasThe place adjustment curve along on modulate, it is f that the signal after obtaining modulating comprises frequency
0Low frequency signal and and V
BiasThe low frequency signal of last superposition High Speed Modulation signal V can not occur with the frequency homophase
RFFrequency-doubled signal.
By above analysis as can be known, be f as long as leach the modulation signal medium frequency
0Low frequency signal and and V
BiasThe phase place of the low frequency signal of last superposition compares, and just can be used for to V
RFSignal amplitude carry out feedback adjusting, lock it in V
πThat is:
If the low frequency signal that leaches represents then that with the low frequency signal homophase of loading current modulation amplitude is littler than signal modulation desired value, should increase; If the low frequency signal that leaches represents then that with the low frequency signal of loading is anti-phase current modulation amplitude is bigger than signal modulation desired value, should reduce.
As shown in Figure 4, be the structured flowchart of device for controlling dynamically of the present invention.
Modulation signal generator is used to produce signals such as Tone, Sine, and Tone is a clock signal, the synchronous sinusoidal signal of Sine signal for leaching from Tone.
Timing controller is used to produce S0, S1 signal, S0 and S1 are the opposite timing controling signal of phase place, these signals and Tone signal come from same clock source to guarantee the synchronism of signal, be the homophase n fractional frequency signal (being eight frequency divisions among the figure) of Tone clock, act on the Sine signal with S0 and S1 as enable signal respectively and obtain V among Fig. 4
AddAnd V
AMSignal waveform.
Signal Tone, S0, S1 and control signal V
Add, V
AMBetween sequential relationship as shown in Figure 5.
Timing controller switches between two kinds of control models with the switch transition signal that is obtained by the homology clock, all begins in integer position to guarantee each the switching, avoids control procedure mistake to occur.
The Error processing module comprises photodetector, amplifier, wave filter, quadrature demodulator and Error processing unit, the output detection signal of lithium niobate modulator is the light signal that is loaded with low frequency signal, be converted into electric signal through behind the photodetector, the low frequency signal that is wherein loaded after the amplification filtering, this filtering gained signal reaction the offset information of signal to be adjusted, with obtain error signal after the demodulation of Tone clock signal, this error signal comprises status signal that signal to be adjusted should increase or reduce and needs the value that increases or reduce, increases or the value that reduces is provided automatically by device.
Because the difference of bias point value of setting and the quantification numerically of the modulation amplitude value of setting, in order to make error signal be suitable for control to bias point initial value or modulation amplitude initial value, need carry out different linear or nonlinear adjustment to error signal by the Error processing unit, obtain error and adjust signal.
Bias point and modulation amplitude control module comprise the first, second, third and the 4th totalizer 41,42,43,44, first, second switch 45,46 of first timing controling signal S0 control, the the 3rd, the 4th switch 47,48 of second timing controling signal S1 control, wherein
Error is adjusted the first input end of signal through first switch, 45 input first adders 41, first input end through the 3rd switch 47 input second adders 42, second input end of the modulation amplitude value of setting input first adder 41, second input end of the signal biasing value of setting input second adder 42, it all is direct current signal that error is adjusted signal, signal biasing value of setting and the signal amplitude value of setting; Before adjusting beginning, signal biasing value of setting and the signal amplitude value of setting provide an initial value earlier, after this along with V
bAnd V
GainThe adjustment respective change.。
Low frequency signal is through the first input end of second switch 46 inputs the 3rd totalizer 43, the output signal V of second adder 42
bImport second input end of the 3rd totalizer 43, the bias voltage input end of the output signal input lithium niobate modulator of the 3rd totalizer 43;
Low frequency signal is through the first input end of the 4th switch 48 inputs the 4th totalizer 44, the output signal V of first adder 41
GainImport second input end of the 4th totalizer 44, the gain control pin of the output signal input signal driver of the 4th totalizer 44, the output signal input high-frequency signal input end of signal driver.
In conjunction with Fig. 4 and Fig. 5, the workflow of The whole control system is described in detail as follows:
The light signal that is loaded with low frequency signal is converted into electric signal through photodetector, the low frequency signal that filtering is wherein loaded after amplifying, according to the analysis of front to Fig. 2, this signal is the offset information of reaction signal to be adjusted, to obtain offset information after this low frequency signal and the demodulation of Tone clock signal, promptly obtain error through the Error processing unit again and adjust signal.When S0 was " 1 ", switch 46 was connected V
AddBe low frequency sinusoidal signal, V
AMBe 0, V
BiasGone up by superposition low frequency signal V
Add, to be connected by the switch 45 of S0 signal controlling simultaneously, error adjustment signal is admitted to totalizer and adjusts V
GainSetting, thereby can adjust V
RFSignal amplitude remain on V
πNear, promptly realized at V
BiasLast loading low frequency signal is controlled V
RFAmplitude; In like manner, when S0 was " 0 ", S1 was " 1 ", switch 48 connections this moment, V
AMBe low frequency sinusoidal signal, V
AddBe 0, low frequency signal V
AMTo V
RFCarry out amplitude modulation(PAM), the switch 47 of S1 signal controlling is connected simultaneously, and error adjustment signal is admitted to totalizer and adjusts V
bSetting, thereby can adjust V
BiasValue remain on V
Bias=V
πNear/2, promptly realized V
RFCarry out the low frequency amplitude modulation(PAM) and control V
Bias
Use example:
When being " 1 ", realizes S0 control to modulation amplitude, if the normal range of signal amplitude is 1V ± 1V, the initial value of modulation amplitude signal is 1V, input signal amplitude is provided with end, superposition low frequency signal on the bias point signal, output detection signal is carried out filtering, the value that the error that obtains after the modulation is adjusted signal is+0.5V, the value of then adjusted modulation amplitude signal is 1.5V, this moment, signal amplitude was provided with end along with adjusted signal value becomes 1.5V, circulation is carried out the adjustment of a new round to adjusted modulation amplitude signal, is 0 up to the error adjustment signal that is carried on the bias point signal.
Embodiment 2
What embodiment 2 provided is a kind of scheme of controlling by to the Loading Control signal of control parameter own, i.e. control to bias voltage realizes by Loading Control signal on bias voltage, and the control of modulation amplitude is realized that by Loading Control signal on modulation amplitude target is with modulation signal V
RFAmplitude be controlled at 2V
π, with bias point voltage V
BiasBe controlled at V
Bias=0.
To bias point voltage V
BiasControl method with at present existing other patent principles are identical, realize by the method that self is loaded the low frequency signal modulation;
To modulation signal V
RFThe control and the V of amplitude
BiasControl method similarly realize that by Loading Control signal on himself signal Fig. 6 has provided modulation signal V
RFThe principle controlled of amplitude, (a) and (b), (c) corresponding V respectively among Fig. 6
RFAmplitude equal 2V
π, greater than 2V
π, less than 2V
πThe time modulation case:
What Fig. 6 (a) provided is as modulation signal V
RFAmplitude equal 2V
π, at V
BiasIn the time of=0, be f with the frequency
0Low frequency signal to modulation signal V
RFModulation case when carrying out amplitude modulation can be seen because V
RFAmplitude equal 2V
π, " 1 " signal and " 0 " signal are all modulated near the crest of adjustment curve, and it is 2f that the signal after obtaining modulating will contain frequency
0Low frequency component, and High Speed Modulation signal V can appear
RFFrequency multiplication and quadruple signal.
What Fig. 6 (b) provided is as modulation signal V
RFAmplitude greater than 2V
π, at V
BiasIn the time of=0, be f with the frequency
0Low frequency signal to modulation signal V
RFModulation case when carrying out amplitude modulation can be seen because V
RFAmplitude greater than 2V
π, " 1 " signal and " 0 " signal are modulated on another edge of two crests crossing adjustment curve respectively, and it is f that the signal after obtaining modulating comprises frequency
0Low frequency signal and with am signals phase place phase difference of pi, and High Speed Modulation signal V can appear
RFFrequency multiplication and quadruple signal.
What Fig. 6 (c) provided is as modulation signal V
RFAmplitude less than 2V
π, at V
BiasIn the time of=0, be f with the frequency
0Low frequency signal to modulation signal V
RFModulation case when carrying out amplitude modulation can be seen because V
RFAmplitude less than 2V
π, " 1 " signal and " 0 " signal respectively the inboard of two crests of adjustment curve along on modulate, it is f that the signal after obtaining modulating comprises frequency
0Low frequency signal and with the am signals homophase, and High Speed Modulation signal V can appear
RFFrequency multiplication and quadruple signal.
By above analysis as can be known, be f as long as leach the modulation signal medium frequency
0Low frequency signal and and V
RFOn the phase place of amplitude modulation low frequency signal compare, just can be used for to V
RFSignal amplitude carry out feedback adjusting, lock it in 2V
πThat is:
If the low frequency signal that leaches represents then that with the low frequency signal homophase of loading current modulation amplitude is littler than signal modulation desired value, should increase; If the low frequency signal that leaches represents then that with the low frequency signal of loading is anti-phase current modulation amplitude is bigger than signal modulation desired value, should reduce.
The structured flowchart of The whole control system as shown in Figure 7, compare with the structured flowchart 4 of embodiment 1, only need to change the position of control signal S0 and S1 loading, the 3rd switch 47 intermodulation that first switch 45 of i.e. first control signal S0 control and the second control signal S1 control the position, wherein identical among signal Tone, Sine, S0, S1 and the embodiment 1, all come from same clock source to guarantee the synchronism of signal.Signal Tone, S0, S1 and control signal V
Add, V
AMBetween sequential relationship equally as shown in Figure 5.
In conjunction with Fig. 6 and Fig. 7, the workflow of The whole control system is described in detail as follows:
The light signal that is loaded with low frequency signal is converted into electric signal through photodetector, the low frequency signal that filtering is wherein loaded after amplifying, according to the analysis of front to Fig. 5, this signal is the offset information of reaction signal to be adjusted, to obtain offset information after this low frequency signal and the demodulation of Tone clock signal, promptly obtain error through the Error processing unit again and adjust signal.When S0 was " 1 ", switch B connected, V
AddBe low frequency sinusoidal signal, V
AMBe 0, V
BiasGone up by superposition low frequency signal V
Add, to be connected by the switch D of S0 signal controlling simultaneously, error adjustment signal is admitted to totalizer and adjusts V
bSetting, thereby can adjust V
BiasValue remain on V
BiasNear=0, promptly realized at V
BiasSelf loads low frequency signal and controls V
BiasIn like manner, when S0 was " 0 ", S1 was " 1 ", and switch A connects, at this moment V
AMBe low frequency sinusoidal signal, V
AddBe 0, low frequency signal V
AMTo V
RFCarry out amplitude modulation(PAM), the switch C of S1 signal controlling connects simultaneously, and error adjustment signal is admitted to totalizer and adjusts V
GainSetting, thereby can adjust V
RFThe signal amplitude value remain on 2V
πNear, promptly realized V
RFSelf carry out amplitude modulation(PAM) and control V
RFAmplitude.
The inventive method and device are to LiNbO
3Modulator bias voltage and modulation amplitude have carried out FEEDBACK CONTROL simultaneously, have improved LiNbO greatly
3The precision of modulator bias point control has reduced because the possibility that the variation of modulation amplitude causes modulating performance to descend has been improved LiNbO
3The reliability of modulator work has effectively improved LiNbO
3The stability of modulator work.
Claims (10)
1, a kind of device for controlling dynamically of lithium niobate modulator, it is characterized in that this device is by loading the control of low frequency signal realization to bias point and modulation amplitude, this device comprises modulation signal generation module, Error processing module and bias point and modulation amplitude control module, wherein
Modulation signal generation module is used to produce the low frequency signal that loads usefulness and conciliates the restituted signal that calls;
The Error processing module is used for that the modulator output detection signal that is loaded with low frequency signal is carried out filtering amplifies, and analyzes acquisition control information by signal correction;
Bias point and modulation amplitude control module are used for to this signal to be controlled or another signal loading low frequency signal to be controlled, and are used for according to control information this signal to be controlled being adjusted, and signal wherein to be controlled is meant bias point signal or modulation amplitude signal.
2, device as claimed in claim 1, it is characterized in that: described Error processing module comprises photodetector, amplifier, wave filter and detuner, the output detection signal of modulator is output error signal behind amplifier, wave filter, detuner, and another input signal of quadrature demodulator is a restituted signal.
3, device as claimed in claim 2, it is characterized in that: described Error processing module also comprises the Error processing unit, be used for the error signal of modulator output is carried out different linear or non-linear adjustment, adjust signal, realize control bias point or modulation amplitude to obtain error.
4, device as claimed in claim 1 is characterized in that: this device also comprises a timing control module, is used to produce two timing controling signals, to realize the control to bias point and modulation amplitude at times.
5, device as claimed in claim 4, it is characterized in that: described restituted signal, low frequency signal and two timing controling signals are the signals that come from same clock source, wherein restituted signal is a clock signal, low frequency signal is this synchronization of clock signals sinusoidal signal, two timing controling signal phase places are opposite, are the homophase n fractional frequency signals of clock signal.
6, device as claimed in claim 5, it is characterized in that: bias point and modulation amplitude control module realize control by the mode that bias point and modulation amplitude add modulation signal mutually, this module comprises the first, second, third and the 4th totalizer (41,42,43,44), first, second switch (45,46) of first timing controling signal control, the the 3rd, the 4th switch (47,48) and the signal driver of the control of second timing controling signal, wherein
Error is adjusted the first input end of signal through first switch (45) input first adder (41), first input end through the 3rd switch (47) input second adder (42), second input end of the modulation amplitude value of setting input first adder (41), second input end of the signal biasing value of setting input second adder (42), it all is direct current signal that error is adjusted signal and signal biasing value of setting and the signal amplitude value of setting, and it all is direct current signal that error is adjusted signal, signal biasing value of setting and the signal amplitude value of setting; Before adjusting beginning, signal biasing value of setting and the signal amplitude value of setting provide an initial value earlier, adjust the signal respective change with error afterwards;
Low frequency signal is through the first input end of second switch (46) input the 3rd totalizer (43), the output signal of second adder (42) is imported second input end of the 3rd totalizer (43), the bias voltage input end of the output signal input lithium niobate modulator of the 3rd totalizer (43);
Low frequency signal is through the first input end of the 4th switch (48) input the 4th totalizer (44), the output signal of first adder (41) is imported second input end of the 4th totalizer (44), the gain control pin of the output signal input signal driver of the 4th totalizer 44, the output signal input high-frequency signal input end of signal driver.
7, device as claimed in claim 6 is characterized in that: bias point and modulation amplitude control module realize control, described first switch in this module and described the 3rd position of the switch intermodulation by bias point and modulation amplitude from the mode that adds modulation signal.
8, a kind of kinetic controlling equation method of lithium niobate modulator is characterized in that, this method is by loading the control of low frequency signal realization to bias point and modulation amplitude, and the control method of this each signal to be controlled may further comprise the steps:
A is input modulator behind superposition one low frequency signal on this signal to be controlled or another signal to be controlled;
B carries out filtering amplification, demodulation with the modulator output detection signal and obtains error and adjust signal;
C adjusts signal according to this error and adjusts the control of this signal realization to be controlled to this signal to be controlled, and described signal to be controlled refers to bias point signal or modulation amplitude signal.
9, kinetic controlling equation method as claimed in claim 8 is characterized in that: at times bias point or modulation amplitude are realized control.
10, method as claimed in claim 9, it is characterized in that: adopt the at times control of two clock control signals realizations bias point and modulation amplitude, low frequency signal described in the steps A is a sinusoidal signal, after among the step B modulator output detection signal being carried out filtering and amplifies, utilize with this low frequency signal clock signal synchronous and carry out demodulation, and described two timing controling signal phase places are opposite, and come from same clock source with clock signal, are the homophase n fractional frequency signals of clock signal.
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| CNA2008100972313A CN101276067A (en) | 2008-05-05 | 2008-05-05 | Dynamic control method and device of lithium niobate modulator |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101807085A (en) * | 2010-03-12 | 2010-08-18 | 上海华魏光纤传感技术有限公司 | Device for controlling and driving biasing and method for controlling and driving light intensity modulator |
| CN102195583A (en) * | 2011-05-24 | 2011-09-21 | 中兴通讯股份有限公司 | Device and method for controlling gain of transimpedance amplifier of lithium niobate (LiNbO3) modulator |
| CN101674138B (en) * | 2009-10-16 | 2013-07-03 | 中兴通讯股份有限公司 | Driving magnitude control device of differential quadrature phase shift keying transmitter and method |
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2008
- 2008-05-05 CN CNA2008100972313A patent/CN101276067A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101674138B (en) * | 2009-10-16 | 2013-07-03 | 中兴通讯股份有限公司 | Driving magnitude control device of differential quadrature phase shift keying transmitter and method |
| CN101807085A (en) * | 2010-03-12 | 2010-08-18 | 上海华魏光纤传感技术有限公司 | Device for controlling and driving biasing and method for controlling and driving light intensity modulator |
| CN102195583A (en) * | 2011-05-24 | 2011-09-21 | 中兴通讯股份有限公司 | Device and method for controlling gain of transimpedance amplifier of lithium niobate (LiNbO3) modulator |
| CN102195583B (en) * | 2011-05-24 | 2016-01-20 | 中兴通讯股份有限公司 | A kind of lithium niobate modulator trans-impedance amplifier gain control and method |
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