CN108833019A - A kind of any Bias point control method of smooth I/Q modulator and control system - Google Patents
A kind of any Bias point control method of smooth I/Q modulator and control system Download PDFInfo
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- CN108833019A CN108833019A CN201810664546.5A CN201810664546A CN108833019A CN 108833019 A CN108833019 A CN 108833019A CN 201810664546 A CN201810664546 A CN 201810664546A CN 108833019 A CN108833019 A CN 108833019A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
Abstract
The invention discloses a kind of any Bias point control methods of smooth I/Q modulator and control system, control method to include：First kind correlation intergal coefficient is calculated using the first disturbing signal and the second disturbing signal；The character voltage coarse value of each modulator is respectively obtained according to the relationship of bias voltage and first kind correlation intergal coefficient；The character voltage exact value of each modulator is obtained by iterative method using the character voltage coarse value of each modulator；The bias voltage of the load needed for each modulator under target bias point is calculated, and the bias voltage that each modulator is loaded correspondingly is set；The value of the second class correlation intergal coefficient is calculated using third disturbing signal, and is thus calculated and referred to related coefficient vector；Real-time related coefficient vector is obtained, and calculates error voltage, the bias voltage of each modulator is then accordingly adjusted using error voltage.The present invention can be realized the control to any bias point of light I/Q modulator and maintain the stabilization of bias point.
Description
Technical field
The invention belongs to fiber optic communications and Microwave photonics field, arbitrarily inclined more particularly, to a kind of smooth I/Q modulator
Set a control method and control system.
Background technique
In fiber optic communication systems, in order to improve channel capacity, increase spectrum efficiency, the high-orders such as QPSK, 16QAM, 64QAM
Modulation format is widely used.And in order to generate the optical signal of higher order modulation formats, light inphase/orthogonal modulates (In-
Phase and Quadrature-phase, IQ) modulator is widely used.Further, since light I/Q modulator works
At non-linear, the characteristic of a variety of high-order harmonic waves can be generated, Microwave photonics field also applies light I/Q modulator more to generate
The frequency microwave signal of frequency multiplication.In order to realize higher order modulation formats signal modulation, need for light I/Q modulator to be biased in most
Good Linear Points, and in order to generate multiple frequence signal, then need for light IQ to be biased in other non-linear points.Since existing smooth IQ is modulated
Device is mostly made of niobic acid lithium material, has higher sensibility to temperature and stress, and the relationship of bias point and bias voltage is
Time-varying, this will lead to the distortion and deterioration of output optical signal.Therefore, it in order to conveniently use light I/Q modulator, needs to lead to
Certain peripheral control circuits are crossed, according to different demands, I/Q modulator is adjusted to different bias points, meanwhile, in angle
After being provided with, it is also necessary to change bias voltage in real time, remain unchanged bias point.
Generally speaking, it realizes the control of any bias point of light I/Q modulator and maintains the stabilization of bias point that there is important meaning
Justice.The structure of common smooth I/Q modulator is as shown in Figure 1, include two sub- MZ Mach-Zehnders (MZMI, MZMQ) and one
Phase delay device P, the sub- MZM modulator of two of them carry out external modulation, and phase to two quadrature phases of input light field respectively
Delayer then defines the phase difference of two sub- modulator output light fields.Currently, light I/Q modulator optimum linear point control and
Any Bias point control of single MZM modulator has obtained extensive research, but these control methods all cannot achieve to light
The control of any bias point of I/Q modulator and the stabilization for maintaining bias point.
Summary of the invention
In view of the drawbacks of the prior art and Improvement requirement, the present invention provides a kind of smooth any Bias point controls of I/Q modulator
Method and control system, its object is to realize the control to any bias point of light I/Q modulator and maintain the stabilization of bias point.
To achieve the above object, according to the invention arbitrarily to be biased in a first aspect, providing a kind of smooth I/Q modulator
Point control method, includes the following steps：
(1) identical first disturbing signal of setting amplitude and the second disturbing signal；Respectively by the first disturbing signal and second
Disturbing signal is attached to bias voltage VIWith bias voltage VQOn, and bias voltage VPDo not add disturbing signal；Wherein, biased electrical
Press VI, bias voltage VQWith bias voltage VPThe direct current of respectively sub- modulator MZMI, sub- modulator MZMQ and female modulator MZMP
The bias voltage of bias input end load；
(2) mother is calculated separately using photosignal, the first disturbing signal and the second disturbing signal that light I/Q modulator exports
The first kind correlation intergal coefficient CID of modulator MZMPP, sub- modulator MZMI first kind correlation intergal coefficient CIDIWith sub- tune
The first kind correlation intergal coefficient CID of device MZMQ processedQ, and thus to obtain sub- modulator MZMI, sub- modulator MZMQ and female modulation
The coarse value of the character voltage of device MZMP；
(3) using the coarse value of the character voltage of each modulator, sub- modulator MZMI, sub- modulator MZMQ and female tune are obtained
The exact value of the character voltage of device MZMP processed；
(4) using the exact value of the character voltage of each modulator, calculating separately each modulator, it is straight under target bias point
The bias voltage loaded needed for bias input end is flowed, and bias voltage V is respectively setI, bias voltage VQWith bias voltage VPIt is right
The value answered, to realize the control to target bias point；
(5) the first disturbing signal is attached to bias voltage VIOn, the second disturbing signal is attached to bias voltage VQOn,
And bias voltage VPDisturbing signal is not added, the first kind correlation intergal coefficient CID under target bias point is thus calculatedPTake
Value, is denoted as
(6) the first disturbing signal and the second disturbing signal are closed, and third disturbing signal is set；It is defeated using light I/Q modulator
Photosignal and third disturbing signal out, calculate separately the second class correlation intergal coefficient of each modulator, and are thus joined
Examine related coefficient vector ψ；
(7) offset phase of current bias point is obtained and as real-time related coefficient vector ψ (t)；According to reference phase
Relationship number vector ψ and real-time related coefficient vector ψ (t) calculate error voltage, and accordingly adjust biased electrical using error voltage
Press VI, bias voltage VQWith bias voltage VP, to stablizing light I/Q modulator in target bias point.
Further, step (2) includes：
(21) bias voltage V is setIWith bias voltage VQIt is 0V and remains unchanged；
(22) change bias voltage VPValue, acquire the output signal of corresponding smooth I/Q modulator and be converted into pair
The ac digital signal I answeredAC, then calculate corresponding first kind correlation intergal coefficient CIDP, thus draw first kind correlation product
Divide coefficient CIDPWith bias voltage VPRelation curveFirst kind correlation intergal coefficient CIDPCalculation formula be：Wherein, T is the time of integration, ωIAnd ωQRespectively the first disturbing signal and second
The angular frequency of disturbing signal；
(23) according to relation curveObtain the coarse value of the character voltage of female modulator MZMP；Wherein, female modulator
The coarse value V of the linear bias voltage of the first of MZMPP(π/2)0For relation curveOn the nearest negative slope zero of distance 0V voltage
The voltage value of point, the coarse value V of the second linear bias voltage of female modulator MZMPP(-π/2)0For relation curveOn away from electricity
Press VP(π/2)0The voltage value of nearest positive slope zero point, the coarse value V of the half-wave voltage of female modulator MZMPπP 0For female modulator
The coarse value V of the linear bias voltage of the first of MZMPP(π/2)0With the coarse value V of the second linear bias voltageP(-π/2)0Difference；
(24) bias voltage V is setPFor VP(π/2)0And remain unchanged, bias voltage V is setQFor 0V and remain unchanged；
(25) change bias voltage VIValue, acquire the output signal of corresponding smooth I/Q modulator and be converted into pair
The ac digital signal I answeredAC, then calculate corresponding first kind correlation intergal coefficient CIDI, thus draw first kind correlation product
Divide coefficient CIDIWith bias voltage VIRelation curveFirst kind correlation intergal coefficient CIDICalculation formula be：
(26) according to relation curveObtain the coarse value of the character voltage of sub- modulator MZMI；Wherein, sub- modulator
The coarse value V of the linear bias voltage of MZMII(π)0For relation curveOn the voltage away from the nearest positive slope zero point of 0V voltage
Value, the coarse value V of the zero phase-shift point voltage of sub- modulator MZMII(0)0For relation curveOn away from voltage VI(π)0Nearest is negative
The voltage value of slope zero point, the coarse value V of the half-wave voltage of sub- modulator MZMIπI 0For the linear bias electricity of sub- modulator MZMI
The coarse value V of pressureI(π)0With the coarse value V of zero phase-shift point voltageI(0)0Difference；
(27) bias voltage V is setPFor VP(π/2)0And remain unchanged, bias voltage V is setIFor VI(π)0And it keeps not
Become；
(28) change bias voltage VQValue, acquire the output signal of corresponding smooth I/Q modulator and be converted into pair
The ac digital signal I answeredAC, then calculate corresponding first kind correlation intergal coefficient CIDQ, thus draw first kind correlation product
Divide coefficient CIDQWith bias voltage VQRelation curveFirst kind correlation intergal coefficient CIDQCalculation formula be：
(29) according to relation curveObtain the coarse value of the character voltage of sub- modulator MZMQ；Wherein, sub- modulator
The coarse value V of the linear bias voltage of MZMQQ(π) 0 is relation curveOn the voltage away from the nearest positive slope zero point of 0V voltage
Value, the coarse value V of the zero phase-shift point voltage of sub- modulator MZMQQ(0)0For relation curveOn away from voltage VQ(π)0Nearest is negative
The voltage value of slope zero point, the coarse value V of the half-wave voltage of sub- modulator MZMQπQ 0For the linear bias electricity of sub- modulator MZMQ
The coarse value V of pressureQ(π)0With the coarse value V of zero phase-shift point voltageQ(0)0Difference.
Further, step (3) includes：
(31) bias voltage V is setIFor VI(π)0And remain unchanged, bias voltage V is setQFor VQ(π)0And it remains unchanged；
Wherein, VI(π)0For the coarse value of the linear bias voltage of sub- modulator MZMI, VQ(π)0For the linear bias of sub- modulator MZMQ
The coarse value of voltage；
(32) with VP(π/2)0For bias voltage VPInitial value find first kind correlation intergal again using Newton iteration method
Coefficient CIDPWith bias voltage VPRelation curve negative slope zero point, to obtain the first linear bias of female modulator MZMP
The exact value V of voltageP(π/2)；With VP(-π/2)0For bias voltage VPInitial value obtain first kind phase using Newton iteration method
Close integral coefficient CIDPWith bias voltage VPRelation curve positive slope zero point, to obtain the second line of female modulator MZMP
The exact value V of property bias voltageP(-π/2)；Wherein, VP(π/2)0And VP(-π/2)0The first of respectively female modulator MZMP is linear
The coarse value of bias voltage and the second linear bias voltage；
(33) the exact value V of the half-wave voltage of female modulator MZMP is calculatedπP, its calculation formula is：VπP=VP(π/2)-VP
(-π/2)；Then the exact value V of the coherent subtraction point voltage of female modulator MZMP is calculatedP(π), its calculation formula is：VP(π)=
VP(π/2)+VπP/2；
(34) using the coarse value of the character voltage of sub- modulator MZMI and sub- modulator MZMQ as corresponding feature
The exact value of voltage, to meet：VI(π)=VI(π)0、VI(0)=VI(0)0、VπI=VπI 0、VQ(π)=VQ(π)0、VQ(0)=
VQ(0)0And VπQ=VπQ 0；Wherein, VI(π) is the exact value of the linear bias voltage of sub- modulator MZMI, VI(0)0And VI(0)
The coarse value and exact value of the zero phase-shift point voltage of respectively sub- modulator MZMI, VπI 0And VπIRespectively sub- modulator MZMI's
The coarse value and exact value of half-wave voltage, VQ(π) is the coarse value of the linear bias voltage of sub- modulator MZMQ, VQ(0)0And VQ
(π) is respectively the coarse value and exact value of the zero phase-shift point voltage of sub- modulator MZMQ, VπQ 0And VπQRespectively sub- modulator MZMQ
Half-wave voltage coarse value and exact value；
(35) bias voltage V is setPFor VP(π) is simultaneously remained unchanged；
(36) with VI(π) is bias voltage VIInitial value, while with VQ(π) is bias voltage VQInitial value, utilize binary ox
Iterative method finds first kind correlation intergal coefficient CID againIWith bias voltage VIRelation curve positive slope zero point and
First kind correlation intergal coefficient CIDQWith bias voltage VQRelation curve positive slope zero point, and thus update sub- modulator
The exact value V of the linear bias voltage of MZMIIThe exact value V of the linear bias voltage of (π) and sub- modulator MZMQQ(π)；
(37) bias voltage V is setQFor VQ(π) is simultaneously remained unchanged, while bias voltage V is arrangedPFor VP(pi/2) is simultaneously kept
It is constant；
(38) with VIIt (0) is bias voltage VIInitial value find first kind correlation intergal system again using Newton iteration method
Number CIDIWith bias voltage VIRelation curve negative slope zero point, and thus update the zero phase-shift point voltage of sub- modulator MZMI
Exact value VI(0)；Then the exact value V of the half-wave voltage of sub- modulator MZMI is updatedπI, its calculation formula is：VπI=VI(π)
+VI(0)；
(39) bias voltage V is setIFor VI(π) is simultaneously remained unchanged, while bias voltage V is arrangedPFor VP(pi/2) is simultaneously kept
It is constant；
(310) with VQIt (0) is bias voltage VQInitial value find first kind correlation intergal system again using Newton iteration method
Number CIDQWith bias voltage VQRelation curve negative slope zero point, and thus update the zero phase-shift point voltage of sub- modulator MZMQ
Exact value VQ(0)；Then the exact value V of the half-wave voltage of sub- modulator MZMQ is updatedπQ, its calculation formula is：VπQ=VQ(π)
+VQ(0)；
(311) using the exact value of updated character voltage, step (35)~(310) are repeated, until sub- modulator
The exact value V of the zero phase-shift point voltage of MZMII(0) and the exact value V of half-wave voltageπIAnd the zero phase-shift of sub- modulator MZMQ
The exact value V of point voltageQ(0) and the exact value V of half-wave voltageπQNo longer change.
Further, it in step (4), using the exact value of the character voltage of each modulator, calculates separately each modulator and exists
The bias voltage loaded needed for its direct current biasing input terminal under target bias point, including：Calculate bias voltage VIValue be：Calculate bias voltage VQValue be：
Calculate bias voltage VPValue be：Wherein,WithRespectively
Sub- modulator MZMI, sub- modulator MZMQ and mother modulator MZMP corresponding offset phase under target bias point；VI(π) is son
The exact value of the linear bias voltage of modulator MZMI, VπIFor the exact value of the half-wave voltage of sub- modulator MZMI, VQ(π) is son
The exact value of the linear bias voltage of modulator MZMQ, VπQFor the exact value of the half-wave voltage of sub- modulator MZMQ, VP(pi/2) is
The exact value of the first linear bias voltage of female modulator MZMP, VπPFor the exact value of the half-wave voltage of female modulator MZMP.
Further, the calculation method in step (6) with reference to related coefficient vector ψ includes：
(61) third disturbing signal is attached to bias voltage VPOn, and bias voltage VIWith bias voltage VQIt does not add
Disturbing signal；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital signal IAC, and count
Calculate the second class correlation intergal coefficient CIS of female modulator MZMPPValueIts calculation formula is：
Wherein,The voltage value of load needed for direct current biasing end for modulator MZMP female under target bias point, T are
The time of integration, ω0For the angular frequency of third disturbing signal；
(62) third disturbing signal is attached to bias voltage VIOn, and bias voltage VPWith bias voltage VQIt does not add
Disturbing signal；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital signal IAC, and count
The second class correlation intergal coefficient CIS of operator modulator MZMIIValueIts calculation formula is：
Wherein,The voltage value of load needed for direct current biasing end for sub- modulator MZMI under target bias point；
(63) third disturbing signal is attached to bias voltage VQOn, and bias voltage VPWith bias voltage VIIt does not add
Disturbing signal；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital signal IAC, and count
The second class correlation intergal coefficient CIS of operator modulator MZMPQValueIts calculation formula is：
Wherein,The voltage value of load needed for direct current biasing end for sub- modulator MZMQ under target bias point；
(64) it calculates and refers to related coefficient vectorWherein：
Wherein, max expression is maximized.
Further, it in step (7), is calculated and is missed according to reference related coefficient vector ψ and real-time related coefficient vector ψ (t)
The method of potential difference is：Establish following total differential equation group：
Then error voltage (Δ V is solved using gradient descent methodI,ΔVQ,ΔVP), wherein Δ VI、ΔVQWith Δ VPRespectively
For sub- modulator MZMI, sub- modulator MZMQ error voltage corresponding with mother modulator MZMP；Wherein, ψI(t)、ψQ(t) and ψP
It (t) is respectively sub- modulator MZMI, sub- modulator MZMQ and mother modulator MZMP corresponding offset phase under current bias point,WithRespectively sub- modulator MZMI, sub- modulator MZMQ and mother modulator MZMP are related in reference
Corresponding offset phase in coefficient vector ψ.
Further, the output signal of light I/Q modulator is converted to by corresponding ac digital signal by photoelectric conversion
IAC, including：It acquires the output signal of light I/Q modulator and light splitting operation is carried out to it；Resulting small component signal conversion will be divided
For electric signal；Electric signal is obtained into corresponding ac digital signal I by analog-to-digital conversionAC。
Second aspect according to the invention, the present invention provides a kind of light IQ provided for realizing first aspect present invention
The control device of any Bias point control method of modulator, including：Photoelectric conversion module, microprocessor and voltage output mould
Block；Then output signal is converted to corresponding ac digital by the output signal that photoelectric conversion module is used to acquire light I/Q modulator
Signal IAC；Microcontroller is used to generate the sampled value of disturbing signal, and according to ac digital signal IACWith the sampling of disturbing signal
Value calculates correlation intergal coefficient, then calculates bias voltage according to correlation intergal coefficient, and the sampled value of disturbing signal is added
The sampled value of bias control signal is obtained on to corresponding bias voltage, finally using the sampled value of bias control signal as voltage
The data of output module input；Voltage output module is used to receive data input and timing input from microcontroller, and passes through number
The sampled value of bias control signal is converted voltage signal by mould conversion, to obtain corresponding bias control signal, then will
Bias control signal inputs to corresponding modulator by the direct current biasing input terminal of modulator；Wherein, disturbing signal is low
Frequency sinusoidal signal, including：First disturbing signal, the second disturbing signal and third disturbing signal；Bias voltage includes：Son modulation
The bias voltage V of the direct current biasing input terminal load of device MZMII, sub- modulator MZMQ the load of direct current biasing input terminal biasing
Voltage VQAnd the bias voltage V of the direct current biasing input terminal load of female modulator MZMPP；Correlation intergal coefficient includes：The first kind
Correlation intergal coefficient CIDP、CIDIAnd CIDQAnd the second class correlation intergal coefficient CISI、CISQAnd CISP。
Further, photoelectric conversion module includes：Splitting ratio is less than 1:9 photo-coupler, photodetector and modulus
Converter；Photo-coupler is for carrying out light splitting operation to the output signal of light I/Q modulator, the big component signal conduct after light splitting
The working signal of light I/Q modulator exports；Photodetector is used to the small component signal that photo-coupler exports being converted to telecommunications
Number；Analog-digital converter is used to electric signal obtaining corresponding ac digital signal I by analog-to-digital conversionAC。
Further, microprocessor is including including disturbing signal generation module, and disturbing signal generation module includes multiple
Direct digital frequency synthesier unit, for generating the sampled value of disturbing signal by direct digital frequency synthesier technology.
In general, contemplated above technical scheme through the invention, can obtain following beneficial effect：
(1) any Bias point control method of smooth I/Q modulator provided by the present invention calculates the first kind according to disturbing signal
Correlation intergal coefficient and the second class correlation intergal coefficient, and further by first kind correlation intergal coefficient and the second class correlation product
The voltage coarse value and voltage exact value for dividing coefficient to calculate each modulator, so as to be directed to the offset phase meter of any bias point
The bias voltage that each modulator should load is calculated, and bias voltage is adjusted in real time.Therefore, it can be realized and light IQ modulated
Have a high regard for the modulation of meaning bias point, and maintains the stabilization of bias point simultaneously.
(2) any Bias point control method of smooth I/Q modulator provided by the present invention calculates the first kind according to disturbing signal
Correlation intergal coefficient and the second class correlation intergal coefficient, and further by first kind correlation intergal coefficient and the second class correlation product
Coefficient is divided to complete relevant calculating and adjusting；It is provided by the present invention since the method that coherent detection is utilized analyzes disturbing signal
Control method adjustment speed it is fast, and degree of regulation is high.
(3) any Bias point control method of smooth I/Q modulator provided by the present invention, according to reference related coefficient vector
When calculating error voltage with real-time related coefficient vector, total differential equation is first established, then solves error using gradient descent method
Voltage is not influenced so that the control stability of bias point is high by temperature change and mechanical oscillation.
(4) any Bias point control method of smooth I/Q modulator provided by the present invention, in the control for realizing any bias point
While, moreover it is possible to other device parameters of light I/Q modulator, such as half-wave voltage are got, therefore wider array of answer can be suitable for
Use range.
(5) control device provided by the present invention, disturbing signal are generated by microprocessor and voltage output module, sampling
Value is known quantity, is conducive to the realization of coherent detection.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of existing smooth I/Q modulator；
Fig. 2 is the structural schematic diagram of existing MZM modulator；
Fig. 3 is the electro-optical characteristic curves figure of existing MZM modulator；
Fig. 4 is control device structure chart provided in an embodiment of the present invention；
Fig. 5 is double disturbance injecting principle figures provided in an embodiment of the present invention；
Fig. 6 is single disturbance injecting principle figure provided in an embodiment of the present invention；(a) female modulator is injected into for single disturbing signal
The schematic diagram of MZMP；(b) schematic diagram of sub- modulator MZMI is injected into for single disturbing signal；(c) it is injected into for single disturbing signal
The schematic diagram of female modulator MZMQ.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
Not constituting a conflict with each other can be combined with each other.
Before the technical solution that the present invention will be described in detail, first the result of light I/Q modulator is briefly described.
The structure of common smooth I/Q modulator is as shown in Figure 1, include two sub- MZ Mach-Zehnder (sub- modulators
MZMI, sub- modulator MZMQ) and a phase delay device P (female modulator MZMP), the sub- MZM modulator of two of them is respectively to defeated
Two quadrature phases for entering light field carry out external modulation, and phase delay device then defines the phase of two sub- modulator output light fields
Difference.The structure of single MZM modulator is as shown in Fig. 2, the electric light phase shift slide comprising upper and lower two-arm, two slides constitute interference knot
Structure.In optical communication system, in order to guarantee the linear modulation of rf signal, sub- MZM modulator needs to control the line in amplitude
Property point, i.e. power minimum point, at this time the phase difference of sub- two slides of MZM modulator be 180 °.And in order to generate high order scheme
Optical signal then needs to guarantee the orthogonality of two sub- modulator output light field phases, the i.e. phase of control phase delay device P delay
It is ± 90 °.The electro-optical characteristic curves figure of single MZM modulator is as shown in Figure 3.As seen from Figure 1, Figure 2, light I/Q modulator and son
The structure of MZM modulator has similitude, therefore, is equivalent to the biasing control of phase delay device P to equivalent mother's MZM structure
Biasing control.In addition, light I/Q modulator is controlled in nonlinear operation point often, then input height in Microwave photonics field
Frequency cosine and sine signal, so that input signal frequency multiplication is generated the radio frequency cosine and sine signal of higher frequency.Therefore, light IQ modulation is realized
Any setting of device bias point and stabilization are of great significance.
As shown in figure 4, control device provided by the present invention includes：Photoelectric conversion module, microcontroller and voltage output
Module；
Photoelectric conversion module includes：Splitting ratio is less than 1:9 photo-coupler, photodetector (PD) and analog-digital converter
(ADC)；Photo-coupler is for carrying out light splitting operation to the output signal of light I/Q modulator, and the big component signal after light splitting is as light
The working signal of I/Q modulator exports；The splitting ratio of photo-coupler can also be 5:95,1:99 etc., but its small component output signal
10% of power no more than general power, to guarantee that the working signal of light I/Q modulator has enough power；Photodetector is used
Electric signal is converted in the small component signal for exporting photo-coupler；Analog-digital converter is for obtaining electric signal by analog-to-digital conversion
To corresponding ac digital signal IAC；
Microcontroller includes disturbing signal generation module, and disturbing signal generation module includes multiple Direct Digital frequencies
(DDS) unit is synthesized, for generating the sampled value of disturbing signal by direct digital frequency synthesier technology；Disturbing signal generates
Module further includes that number multiplies unit, for the amplitude of disturbing signal to be arranged；
Microcontroller further includes correlation intergal computing module and biasing computing module；Correlation intergal computing module is for receiving
Ac digital signal IACWith the sampled value of disturbing signal, and thus calculate correlation intergal coefficient；It biases computing module and is used for basis
Correlation intergal coefficient calculates bias voltage, and is adjusted in real time to bias voltage；
Microcontroller further includes addition unit, for the sampled value of disturbing signal to be attached to offset signal, thus
It is inputted to the sampled value of bias control signal, and using the sampled value of bias control signal as the data of voltage output module；
Voltage output module includes digital-to-analogue conversion (DAC) unit；Voltage output module is used to receive data from microcontroller
Input and timing input, and voltage signal is converted for the sampled value of bias control signal by D/A conversion unit, thus
To corresponding bias control signal, then bias control signal is inputed to by the direct current biasing input terminal of modulator corresponding
Modulator；
Wherein, disturbing signal is Low Frequency Sine Signals, including：First disturbing signal, the second disturbing signal and third
Disturbing signal；Bias voltage includes：The bias voltage V of the direct current biasing input terminal load of sub- modulator MZMII, sub- modulator
The bias voltage V of the direct current biasing input terminal load of MZMQQAnd the direct current biasing input terminal load of female modulator MZMP is inclined
Set voltage VP；Correlation intergal coefficient includes：First kind correlation intergal coefficient CIDP、CIDIAnd CIDQAnd the second class correlation intergal
Coefficient CISI、CISQAnd CISP。
In control device shown in Fig. 4, the execution of the smooth any Bias point control method of I/Q modulator provided by the invention
Process includes the following steps：
S1：Microprocessor calculates separately the sampling of the first disturbing signal and the second disturbing signal according to the sample rate of 48kHz
Value, and by scaling, the amplitude that the first disturbing signal and the second disturbing signal is arranged is 1V, then believes the first disturbance
Number and the sampled value of the second disturbing signal be transferred to voltage output module；Wherein, the frequency of the first disturbing signal is 4.8kHz, the
The frequency of two disturbing signals is 4.0kHz；
S2：According to double disturbance injecting principles shown in fig. 5, bias voltage is arranged by voltage output module, biased electrical is set
Press VI、VQAnd VPInitial value is that the first disturbance disturbing signal is attached to bias voltage V for 0VIOn, constitute control signal VI*；It will
Second disturbing signal is attached to bias voltage VQOn, constitute control signal VQ*；Bias voltage VPDisturbing signal is not added, is directly made
To control signal VP*；Signal V will be controlledI*、VQAnd V *P* the sub- modulator MZMI of light I/Q modulator, sub- modulation are separately input to
The direct current biasing input terminal of device MZMQ and female modulator MZMP；
S3：Mother is calculated separately using photosignal, the first disturbing signal and the second disturbing signal that light I/Q modulator exports
The first kind correlation intergal coefficient CID of modulator MZMPP, sub- modulator MZMI first kind correlation intergal coefficient CIDIWith sub- tune
The first kind correlation intergal coefficient CID of device MZMQ processedQ, and thus to obtain sub- modulator MZMI, sub- modulator MZMQ and female modulation
The coarse value of the character voltage of device MZMP；Specifically comprise the following steps：
S3-1：Bias voltage V is setIWith bias voltage VQIt is 0V and remains unchanged；
S3-2：In -10V~+10V range, step-length 0.5V is taken, V is set graduallyPValue, while utilize photoelectric conversion mould
Block acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital signal IAC, then calculate and correspond to
First kind correlation intergal coefficient CIDP, thus draw first kind correlation intergal coefficient CIDPWith bias voltage VPRelation curveFirst kind correlation intergal coefficient CIDPCalculation formula be：Wherein, T is product
Between timesharing and value is 50ms, ωIAnd ωQThe respectively angular frequency of the first disturbing signal and the second disturbing signal；
S3-3：According to relation curveObtain the coarse value of the character voltage of female modulator MZMP；Wherein, female modulator
The coarse value V of the linear bias voltage of the first of MZMPP(π/2)0For relation curveOn the nearest negative slope zero of distance 0V voltage
The voltage value of point, the second linear bias voltage coarse value V of female modulator MZMPP(-π/2)0For relation curveOn away from voltage VP
(π/2)0The voltage value of nearest positive slope zero point, the coarse value V of the half-wave voltage of female modulator MZMPπP 0For female modulator
The coarse value V of the linear bias voltage of the first of MZMPP(π/2)0With the coarse value V of the second linear bias voltageP(-π/2)0Difference；
S3-4：Bias voltage V is setPFor VP(π/2)0And remain unchanged, bias voltage V is setQFor 0V and remain unchanged；
S3-5：In -10V~+10V range, step-length 0.5V is taken, V is set graduallyIValue, while utilize photoelectric conversion mould
Block acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital signal IAC, then calculate and correspond to
First kind correlation intergal coefficient CIDI, thus draw first kind correlation intergal coefficient CIDIWith bias voltage VIRelation curveFirst kind correlation intergal coefficient CIDICalculation formula be：
S3-6：According to relation curve fI 0Obtain the coarse value of the character voltage of sub- modulator MZMI；Wherein, sub- modulator
The coarse value V of the linear bias voltage of MZMII(π)0For relation curveOn the voltage away from the nearest positive slope zero point of 0V voltage
Value, the coarse value V of the zero phase-shift point voltage of sub- modulator MZMII(0)0For relation curveOn away from voltage VI(π)0Nearest is negative
The voltage value of slope zero point, the coarse value V of the half-wave voltage of sub- modulator MZMIπI 0For the linear bias electricity of sub- modulator MZMI
The coarse value V of pressureI(π)0With the coarse value V of zero phase-shift point voltageI(0)0Difference；
S3-7：Bias voltage V is setPFor VP(π/2)0And remain unchanged, bias voltage V is setIFor VI(π)0And it keeps not
Become；
S3-8：In -10V~+10V range, step-length 0.5V is taken, V is set graduallyQValue, while utilize photoelectric conversion mould
Block acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital signal IAC, then calculate and correspond to
First kind correlation intergal coefficient CIDQ, thus draw first kind correlation intergal coefficient CIDQWith bias voltage VQRelation curveFirst kind correlation intergal coefficient CIDQCalculation formula be：
S3-9：According to relation curveObtain the character voltage coarse value of sub- modulator MZMQ；Wherein, sub- modulator MZMQ
Linear bias voltage coarse value VQ(π)0For relation curveOn the voltage value away from the nearest positive slope zero point of 0V voltage, son
The coarse value V of the zero phase-shift point voltage of modulator MZMQQ(0)0For relation curveOn away from voltage VQ(π)0Nearest negative slope zero
The voltage value of point, the coarse value V of the half-wave voltage of sub- modulator MZMQπQ 0For sub- modulator MZMQ linear bias voltage it is thick
Slightly value VQ(π)0With the coarse value V of zero phase-shift point voltageQ(0)0Difference；
S4：Using the coarse value of the character voltage of each modulator, sub- modulator MZMI, sub- modulator MZMQ and female tune are obtained
The exact value of the character voltage of device MZMP processed；Specifically comprise the following steps：
S4-1：Bias voltage V is setIFor VI(π)0And remain unchanged, bias voltage V is setQFor VQ(π)0And it remains unchanged；
Wherein, VI(π)0For the coarse value of the linear bias voltage of sub- modulator MZMI, VQ(π)0For the linear bias of sub- modulator MZMQ
The coarse value of voltage；
S4-2：With VP(π/2)0For bias voltage VPInitial value find first kind correlation product again using Newton iteration method
Divide coefficient CIDPWith bias voltage VPRelation curve negative slope zero point, thus obtain female modulator MZMP first it is linear partially
Set the exact value V of voltageP(π/2)；With VP(-π/2)0For bias voltage VPInitial value obtain the first kind using Newton iteration method
Correlation intergal coefficient CIDPWith bias voltage VPRelation curve positive slope zero point, to obtain the second of female modulator MZMP
The exact value V of linear bias voltageP(-π/2)；Wherein, VP(π/2)0And VP(-π/2)0The First Line of respectively female modulator MZMP
The coarse value of property bias voltage and the second linear bias voltage；
S4-3：Calculate the exact value V of the half-wave voltage of female modulator MZMPπP, its calculation formula is：VπP=VP(π/2)-VP
(-π/2)；Then the exact value V of the coherent subtraction point voltage of female modulator MZMP is calculatedP(π), its calculation formula is：VP(π)=
VP(π/2)+VπP/2；
S4-4：Using the coarse value of the character voltage of sub- modulator MZMI and sub- modulator MZMQ as corresponding feature
The exact value of voltage, to meet：VI(π)=VI(π)0、VI(0)=VI(0)0、VπI=VπI 0、VQ(π)=VQ(π)0、VQ(0)=
VQ(0)0And VπQ=VπQ 0；Wherein, VI(π) is the exact value of the linear bias voltage of sub- modulator MZMI, VI(0)0And VI(0)
The coarse value and exact value of the zero phase-shift point voltage of respectively sub- modulator MZMI, VπI 0And VπIRespectively sub- modulator MZMI's
The coarse value and exact value of half-wave voltage, VQ(π) is the coarse value of the linear bias voltage of sub- modulator MZMQ, VQ(0)0And VQ
(π) is respectively the coarse value and exact value of the zero phase-shift point voltage of sub- modulator MZMQ, VπQ 0And VπQRespectively sub- modulator MZMQ
Half-wave voltage coarse value and exact value；
S4-5：Bias voltage V is setPFor VP(π) is simultaneously remained unchanged；
S4-6：With VI(π) is bias voltage VIInitial value, while with VQ(π) is bias voltage VQInitial value, utilize binary
Newton iteration method finds first kind correlation intergal coefficient CID againIWith bias voltage VIRelation curve positive slope zero point with
And first kind correlation intergal coefficient CIDQWith bias voltage VQRelation curve positive slope zero point, and thus update sub- modulator
The exact value V of the linear bias voltage of MZMIIThe exact value V of the linear bias voltage of (π) and sub- modulator MZMQQ(π)；
S4-7：Bias voltage V is setQFor VQ(π) is simultaneously remained unchanged, while bias voltage V is arrangedPFor VP(pi/2) is simultaneously kept
It is constant；
S4-8：With VIIt (0) is bias voltage VIInitial value seek again using Newton iteration method and state first kind correlation intergal system
Number CIDIWith bias voltage VIRelation curve negative slope zero point, and thus update the zero phase-shift point voltage of sub- modulator MZMI
Exact value VI(0)；Then the exact value V of the half-wave voltage of sub- modulator MZMI is updatedπI, its calculation formula is：VπI=VI(π)
+VI(0)；
S4-9：Bias voltage V is setIFor VI(π) is simultaneously remained unchanged, while bias voltage V is arrangedPFor VP(pi/2) is simultaneously kept
It is constant；
S4-10：With VQIt (0) is bias voltage VQInitial value find first kind correlation intergal again using Newton iteration method
Coefficient CIDQWith bias voltage VQRelation curve negative slope zero point, and thus update the zero phase-shift point electricity of sub- modulator MZMQ
The exact value V of pressureQ(0)；Then the exact value V of the half-wave voltage of sub- modulator MZMQ is updatedπQ, its calculation formula is：VπQ=VQ
(π)+VQ(0)；
S4-11：Using the exact value of updated character voltage, step S4-5~S4-10 is repeated, until sub- modulator
The exact value V of the zero phase-shift point voltage of MZMII(0) and the exact value V of half-wave voltageπIAnd the zero phase-shift point of modulator MZMQ
The exact value V of voltageQ(0) and the exact value V of half-wave voltageπQNo longer change；
S5：Using the exact value of the character voltage of each modulator, calculating separately each modulator, it is straight under target bias point
The bias voltage loaded needed for bias input end is flowed, and bias voltage V is respectively setI, bias voltage VQWith bias voltage VPIt is right
The value answered, to realize the control to target bias point；Specifically, bias voltage VIValue be：Bias voltage VQValue be：
Bias voltage VPValue be：Wherein,WithRespectively son is adjusted
Device MZMI processed, sub- modulator MZMQ and mother modulator the MZMP corresponding offset phase under target bias point；VI(π) is son modulation
The exact value of the linear bias voltage of device MZMI, VπIFor the exact value of the half-wave voltage of sub- modulator MZMI, VQ(π) is son modulation
The exact value of the linear bias voltage of device MZMQ, VπQFor the exact value of the half-wave voltage of sub- modulator MZMQ, VP(pi/2) is female adjust
The exact value of the first linear bias voltage of device MZMP processed, VπPFor the exact value of the half-wave voltage of female modulator MZMP；
S6：First disturbing signal is attached to bias voltage VIOn, the second disturbing signal is attached to bias voltage VQOn,
And bias voltage VPDisturbing signal is not added, the first kind correlation intergal coefficient CID under target bias point is thus calculatedPTake
Value, is denoted as
S7：The first disturbing signal and the second disturbing signal are closed, and the third that frequency is 3.0kHz, amplitude is 0.1V is set
Disturbing signal；Using the photosignal and third disturbing signal of the output of light I/Q modulator, the second class of each modulator is calculated separately
Correlation intergal coefficient, and thus obtain with reference to related coefficient vector ψ；
Calculation method with reference to related coefficient vector ψ includes：
S7-1：Third disturbing signal is attached to bias voltage VPOn, and bias voltage VIWith bias voltage VQIt does not add
Disturbing signal, as shown in Fig. 6 (a)；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding exchange number
Word signal IAC, and calculate the second class correlation intergal coefficient CIS of female modulator MZMPPValueIt calculates public
Formula is：
Wherein,The voltage value of load needed for direct current biasing end for modulator MZMP female under target bias point, T are
The time of integration, ω0For the angular frequency of third disturbing signal；
S7-2：Third disturbing signal is attached to bias voltage VIOn, and bias voltage VPWith bias voltage VQIt does not add
Disturbing signal, as shown in Fig. 6 (b)；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding exchange number
Word signal IAC, and calculate the second class correlation intergal coefficient CIS of sub- modulator MZMIIValueIts calculation formula
For：
Wherein,The voltage value of load needed for direct current biasing end for sub- modulator MZMI under target bias point；
S7-3：Third disturbing signal is attached to bias voltage VQOn, and bias voltage VPWith bias voltage VIIt does not add
Disturbing signal, as shown in Fig. 6 (c)；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding exchange number
Word signal IAC, and calculate the second class correlation intergal coefficient CIS of sub- modulator MZMPQValueIts calculation formula
For：
Wherein,The voltage value of load needed for direct current biasing end for sub- modulator MZMQ under target bias point；
S7-4：It calculates and refers to related coefficient vectorWherein：
Wherein, max expression is maximized；
S8：Obtain the offset phase of current bias point and as real-time related coefficient vector ψ (t)=[ψI(t),ψQ
(t),ψP(t)]；Following total differential equation group is established according to reference related coefficient vector ψ and real-time related coefficient vector ψ (t)：
Then error voltage (Δ V is solved using gradient descent methodI,ΔVQ,ΔVP), wherein Δ VI、ΔVQWith Δ VPRespectively
For sub- modulator MZMI, sub- modulator MZMQ error voltage corresponding with mother modulator MZMP；And accordingly using error voltage
Adjust bias voltage VI, bias voltage VQWith bias voltage VP, thus stable bias point；
Wherein, ψI(t)、ψQ(t) and ψPIt (t) is respectively that sub- modulator MZMI, sub- modulator MZMQ and mother modulator MZMP exist
Corresponding offset phase under current bias point,WithRespectively sub- modulator MZMI, sub- modulator
MZMQ and mother modulator MZMP corresponding offset phase in reference related coefficient vector ψ.
Any Bias point control method of smooth I/Q modulator provided by the present invention, realize control to any bias point and
Stablize, and by calculating first kind correlation intergal coefficient and the second class correlation intergal coefficient, to utilize the method for coherent detection
Disturbing signal is analyzed, therefore adjustment speed is fast and degree of regulation is high.In the present embodiment, it adjusts time-consuming less than 30s, adjusting resolution
Rate is about ± 0.02V, compared to existing control method, has apparent advantage.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (10)
1. a kind of any Bias point control method of smooth I/Q modulator, which is characterized in that include the following steps：
(1) identical first disturbing signal of setting amplitude and the second disturbing signal；Respectively by first disturbing signal and described
Second disturbing signal is attached to bias voltage VIWith bias voltage VQOn, and bias voltage VPDo not add disturbing signal；Wherein, institute
State bias voltage VI, the bias voltage VQWith the bias voltage VPRespectively sub- modulator MZMI, sub- modulator MZMQ and mother
The bias voltage of the direct current biasing input terminal load of modulator MZMP；
(2) it is counted respectively using photosignal, first disturbing signal and second disturbing signal of light I/Q modulator output
Calculate the first kind correlation intergal coefficient CID of female modulator MZMPP, sub- modulator MZMI first kind correlation intergal coefficient CIDIWith
The first kind correlation intergal coefficient CID of sub- modulator MZMQQ, and thus to obtain sub- modulator MZMI, sub- modulator MZMQ and mother
The coarse value of the character voltage of modulator MZMP；
(3) using the coarse value of the character voltage of each modulator, sub- modulator MZMI, sub- modulator MZMQ and female modulator are obtained
The exact value of the character voltage of MZMP；
(4) using the exact value of the character voltage of each modulator, it is inclined to calculate separately each modulator its direct current under target bias point
The bias voltage loaded needed for input terminal is set, and the bias voltage V is respectively setI, the bias voltage VQWith the biased electrical
Press VPFor corresponding value, to realize the control to target bias point；
(5) first disturbing signal is attached to the bias voltage VIOn, second disturbing signal is attached to described inclined
Set voltage VQOn, and the bias voltage VPDisturbing signal is not added, the first kind phase under target bias point is thus calculated
Close integral coefficient CIDPValue, be denoted as
(6) first disturbing signal and second disturbing signal are closed, and third disturbing signal is set；It is modulated using light IQ
The photosignal of device output and the third disturbing signal, calculate separately the second class correlation intergal coefficient of each modulator, and by
This is obtained with reference to related coefficient vector ψ；
(7) offset phase of current bias point is obtained and as real-time related coefficient vector ψ (t)；Phase is referred to according to described
Relationship number vector ψ and the real-time related coefficient vector ψ (t) calculate error voltage, and are accordingly adjusted using the error voltage
Save the bias voltage VI, the bias voltage VQWith the bias voltage VP, to stablizing light I/Q modulator in target bias
Point.
2. any Bias point control method of light I/Q modulator as described in claim 1, which is characterized in that step (2) packet
It includes：
(21) the bias voltage V is setIWith the bias voltage VQIt is 0V and remains unchanged；
(22) change the bias voltage VPValue, acquire the output signal of corresponding smooth I/Q modulator and be converted into pair
The ac digital signal I answeredAC, then calculate corresponding first kind correlation intergal coefficient CIDP, thus draw the first kind phase
Close integral coefficient CIDPWith the bias voltage VPRelation curveThe first kind correlation intergal coefficient CIDPCalculating it is public
Formula is：Wherein, T is the time of integration, ωIAnd ωQThe respectively described first disturbance letter
Number and second disturbing signal angular frequency；
(23) according to the relation curveObtain the coarse value of the character voltage of female modulator MZMP；Wherein, female modulator
The coarse value V of the linear bias voltage of the first of MZMPP(π/2)0For the relation curveOn distance 0V voltage it is nearest it is negative tiltedly
The voltage value of rate zero point, the coarse value V of the second linear bias voltage of female modulator MZMPP(-π/2)0For the relation curveOn away from voltage VP(π/2)0The voltage value of nearest positive slope zero point, the coarse value V of the half-wave voltage of female modulator MZMPπP 0
For the coarse value V of the first linear bias voltage of female modulator MZMPP(π/2)0With the coarse value V of the second linear bias voltageP(-
π/2)0Difference；
(24) the bias voltage V is setPFor VP(π/2)0And remain unchanged, the bias voltage V is setQFor 0V and keep not
Become；
(25) change the bias voltage VIValue, acquire the output signal of corresponding smooth I/Q modulator and be converted into pair
The ac digital signal I answeredAC, then calculate corresponding first kind correlation intergal coefficient CIDI, thus draw the first kind phase
Close integral coefficient CIDIWith the bias voltage VIRelation curveThe first kind correlation intergal coefficient CIDICalculating it is public
Formula is：
(26) according to the relation curveObtain the coarse value of the character voltage of sub- modulator MZMI；Wherein, sub- modulator
The coarse value V of the linear bias voltage of MZMII(π)0For the relation curveOn away from the nearest positive slope zero point of 0V voltage
Voltage value, the coarse value V of the zero phase-shift point voltage of sub- modulator MZMII(0)0For the relation curveOn away from voltage VI(π)0
The voltage value of nearest negative slope zero point, the coarse value V of the half-wave voltage of sub- modulator MZMIπI 0For the line of sub- modulator MZMI
The coarse value V of property bias voltageI(π)0With the coarse value V of zero phase-shift point voltageI(0)0Difference；
(27) the bias voltage V is setPFor VP(π/2)0And remain unchanged, the bias voltage V is setIFor VI(π)0And it keeps
It is constant；
(28) change the bias voltage VQValue, acquire the output signal of corresponding smooth I/Q modulator and be converted into pair
The ac digital signal I answeredAC, then calculate corresponding first kind correlation intergal coefficient CIDQ, thus draw the first kind phase
Close integral coefficient CIDQWith the bias voltage VQRelation curveThe first kind correlation intergal coefficient CIDQCalculating it is public
Formula is：
(29) according to the relation curveObtain the coarse value of the character voltage of sub- modulator MZMQ；Wherein, sub- modulator
The coarse value V of the linear bias voltage of MZMQQ(π)0For the relation curveOn away from the nearest positive slope zero point of 0V voltage
Voltage value, the coarse value V of the zero phase-shift point voltage of sub- modulator MZMQQ(0)0For the relation curveOn away from voltage VQ(π)0
The voltage value of nearest negative slope zero point, the coarse value V of the half-wave voltage of sub- modulator MZMQπQ 0For the line of sub- modulator MZMQ
The coarse value V of property bias voltageQ(π)0With the coarse value V of zero phase-shift point voltageQ(0)0Difference.
3. any Bias point control method of light I/Q modulator as described in claim 1, which is characterized in that step (3) packet
It includes：
(31) the bias voltage V is setIFor VI(π)0And remain unchanged, the bias voltage V is setQFor VQ(π)0And it keeps not
Become；Wherein, VI(π)0For the coarse value of the linear bias voltage of sub- modulator MZMI, VQ(π)0For the linear of sub- modulator MZMQ
The coarse value of bias voltage；
(32) with VP(π/2)0For the bias voltage VPInitial value it is related to find the first kind again using Newton iteration method
Integral coefficient CIDPWith the bias voltage VPRelation curve negative slope zero point, to obtain the first of female modulator MZMP
The exact value V of linear bias voltageP(π/2)；With VP(-π/2)0For the bias voltage VPInitial value, using Newton iteration method,
Obtain the first kind correlation intergal coefficient CIDPWith the bias voltage VPRelation curve positive slope zero point, to obtain
The exact value V of the second linear bias voltage of female modulator MZMPP(-π/2)；Wherein, VP(π/2)0And VP(-π/2)0It is respectively female
The coarse value of the linear bias voltage of the first of modulator MZMP and the second linear bias voltage；
(33) the exact value V of the half-wave voltage of female modulator MZMP is calculatedπP, its calculation formula is：VπP=VP(π/2)-VP(-π/
2)；Then the exact value V of the coherent subtraction point voltage of female modulator MZMP is calculatedP(π), its calculation formula is：VP(π)=VP(π/
2)+VπP/2；
(34) using the coarse value of the character voltage of sub- modulator MZMI and sub- modulator MZMQ as corresponding character voltage
Exact value, to meet：VI(π)=VI(π)0、VI(0)=VI(0)0、VπI=VπI 0、VQ(π)=VQ(π)0、VQ(0)=VQ(0)0
And VπQ=VπQ 0；Wherein, VI(π) is the exact value of the linear bias voltage of sub- modulator MZMI, VI(0)0And VI(0) it is respectively
The coarse value and exact value of the zero phase-shift point voltage of sub- modulator MZMI, VπI 0And VπIThe half-wave electricity of respectively sub- modulator MZMI
The coarse value and exact value of pressure, VQ(π) is the coarse value of the linear bias voltage of sub- modulator MZMQ, VQ(0)0And VQ(π) difference
For the coarse value and exact value of the zero phase-shift point voltage of sub- modulator MZMQ, VπQ 0And VπQThe half-wave of respectively sub- modulator MZMQ
The coarse value and exact value of voltage；
(35) the bias voltage V is setPFor VP(π) is simultaneously remained unchanged；
(36) with VI(π) is the bias voltage VIInitial value, while with VQ(π) is the bias voltage VQInitial value, utilize two
First Newton iteration method finds the first kind correlation intergal coefficient CID againIWith the bias voltage VIRelation curve just
Slope zero point and the first kind correlation intergal coefficient CIDQWith the bias voltage VQRelation curve positive slope zero point,
And thus update the exact value V of the linear bias voltage of sub- modulator MZMIIThe linear bias voltage of (π) and sub- modulator MZMQ
Exact value VQ(π)；
(37) the bias voltage V is setQFor VQ(π) is simultaneously remained unchanged, while the bias voltage V is arrangedPFor VP(pi/2) is simultaneously protected
It holds constant；
(38) with VIIt (0) is the bias voltage VIInitial value find the first kind correlation product again using Newton iteration method
Divide coefficient CIDIWith the bias voltage VIRelation curve negative slope zero point, and thus update zero phase of sub- modulator MZMI
Move the exact value V of point voltageI(0)；Then the exact value V of the half-wave voltage of sub- modulator MZMI is updatedπI, its calculation formula is：
VπI=VI(π)+VI(0)；
(39) the bias voltage V is setIFor VI(π) is simultaneously remained unchanged, while the bias voltage V is arrangedPFor VP(pi/2) is simultaneously protected
It holds constant；
(310) with VQIt (0) is the bias voltage VQInitial value find the first kind correlation product again using Newton iteration method
Divide coefficient CIDQWith the bias voltage VQRelation curve negative slope zero point, and thus update zero phase of sub- modulator MZMQ
Move the exact value V of point voltageQ(0)；Then the exact value V of the half-wave voltage of sub- modulator MZMQ is updatedπQ, its calculation formula is：
VπQ=VQ(π)+VQ(0)；
(311) using the exact value of updated character voltage, step (35)~(310) are repeated, until sub- modulator MZMI
The exact value V of zero phase-shift point voltageI(0) and the exact value V of half-wave voltageπIAnd the zero phase-shift point voltage of sub- modulator MZMQ
Exact value VQ(0) and the exact value V of half-wave voltageπQNo longer change.
4. any Bias point control method of light I/Q modulator as described in claim 1, which is characterized in that in the step (4),
Using the exact value of the character voltage of each modulator, each modulator its direct current biasing input terminal under target bias point is calculated separately
The bias voltage of required load, including：Calculate the bias voltage VIValue be：
Calculate the bias voltage VQValue be：Calculate the bias voltage VPTake
Value is：
Wherein,WithRespectively sub- modulator MZMI, sub- modulator MZMQ and mother modulator MZMP are in target bias point
Under corresponding offset phase；VI(π) is the exact value of the linear bias voltage of sub- modulator MZMI, VπIFor sub- modulator MZMI's
The exact value of half-wave voltage, VQ(π) is the exact value of the linear bias voltage of sub- modulator MZMQ, VπQFor sub- modulator MZMQ's
The exact value of half-wave voltage, VP(pi/2) is the exact value of the first linear bias voltage of female modulator MZMP, V πPFor female modulator
The exact value of the half-wave voltage of MZMP.
5. any Bias point control method of light I/Q modulator as described in claim 1, which is characterized in that in the step (6)
The calculation method with reference to related coefficient vector ψ includes：
(61) the third disturbing signal is attached to the bias voltage VPOn, and the bias voltage VIWith the biased electrical
Press VQDisturbing signal is not added；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital
Signal IAC, and calculate the second class correlation intergal coefficient CIS of female modulator MZMPPValueIts calculation formula
For：
Wherein,The voltage value of load needed for direct current biasing end for modulator MZMP female under target bias point, T is integral
Time, ω0For the angular frequency of the third disturbing signal；
(62) the third disturbing signal is attached to the bias voltage VIOn, and the bias voltage VPWith the biased electrical
Press VQDisturbing signal is not added；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital
Signal IAC, and calculate the second class correlation intergal coefficient CIS of sub- modulator MZMIIValueIts calculation formula is：
Wherein,The voltage value of load needed for direct current biasing end for sub- modulator MZMI under target bias point；
(63) the third disturbing signal is attached to the bias voltage VQOn, and the bias voltage VPWith the biased electrical
Press VIDisturbing signal is not added；It acquires the output signal of corresponding smooth I/Q modulator and is converted into corresponding ac digital
Signal IAC, and calculate the second class correlation intergal coefficient CIS of sub- modulator MZMPQValueIts calculation formula is：
Wherein,The voltage value of load needed for direct current biasing end for sub- modulator MZMQ under target bias point；
(64) it calculates described with reference to related coefficient vectorWherein：
Wherein, max expression is maximized.
6. any Bias point control method of light I/Q modulator as described in claim 1, which is characterized in that in the step (7),
It is according to the method that the reference related coefficient vector ψ and the real-time related coefficient vector ψ (t) calculate error voltage：It establishes
Following total differential equation group：
Then error voltage (Δ V is solved using gradient descent methodI,ΔVQ,ΔVP), wherein Δ VI、ΔVQWith Δ VPIt is respectively sub
Modulator MZMI, sub- modulator MZMQ error voltage corresponding with mother modulator MZMP；Wherein, ψI(t)、ψQ(t) and ψP(t) divide
Not Wei sub- modulator MZMI, sub- modulator MZMQ and mother modulator MZMP corresponding offset phase under current bias point,WithRespectively sub- modulator MZMI, sub- modulator MZMQ and mother modulator MZMP are in the reference
Corresponding offset phase in related coefficient vector ψ.
7. any Bias point control method of light I/Q modulator as described in claim 2 or claim 5, which is characterized in that logical
It crosses photoelectric conversion and the output signal of light I/Q modulator is converted into corresponding ac digital signal IAC, including：Acquire light IQ modulation
The output signal of device simultaneously carries out light splitting operation to it；Resulting small component signal will be divided and be converted to electric signal；By the telecommunications
Number corresponding ac digital signal I is obtained by analog-to-digital conversionAC。
8. a kind of control device for realizing any Bias point control method of light I/Q modulator as described in claim 1,
It is characterized in that, including：Photoelectric conversion module, microprocessor and voltage output module；
Then the output signal is converted to correspondence by the output signal that the photoelectric conversion module is used to acquire light I/Q modulator
Ac digital signal IAC；
The microcontroller is used to generate the sampled value of disturbing signal, and according to the ac digital signal IACBelieve with the disturbance
Number sampled value calculate correlation intergal coefficient, bias voltage is then calculated according to the correlation intergal coefficient, and by the disturbance
The sampled value of signal, which is attached on corresponding bias voltage, obtains the sampled value of bias control signal, finally controls the biasing
The sampled value of signal is inputted as the data of the voltage output module；
The voltage output module is used to receive data input and timing input from the microcontroller, and will by digital-to-analogue conversion
The sampled value of the bias control signal is converted into voltage signal, so that corresponding bias control signal is obtained, it then will be described
Bias control signal inputs to corresponding modulator by the direct current biasing input terminal of modulator；
Wherein, the disturbing signal is Low Frequency Sine Signals, including the first disturbing signal, the second disturbing signal and third are disturbed
Dynamic signal；The bias voltage includes the bias voltage V of the direct current biasing input terminal load of sub- modulator MZMII, sub- modulator
The bias voltage V of the direct current biasing input terminal load of MZMQQAnd the direct current biasing input terminal load of female modulator MZMP is inclined
Set voltage VP；The correlation intergal coefficient includes：First kind correlation intergal coefficient CIDP、CIDIAnd CIDQAnd second class it is related
Integral coefficient CISI、CISQAnd CISP。
9. control device as claimed in claim 8, which is characterized in that the photoelectric conversion module includes：Splitting ratio is less than 1:9
Photo-coupler, photodetector and analog-digital converter；
The photo-coupler is for carrying out light splitting operation to the output signal of light I/Q modulator, the big component signal conduct after light splitting
The working signal of light I/Q modulator exports；
The photodetector is used to the small component signal that the photo-coupler exports being converted to electric signal；
The analog-digital converter is used to the electric signal obtaining corresponding ac digital signal I by analog-to-digital conversionAC。
10. control device as claimed in claim 8, which is characterized in that the microprocessor includes generating including disturbing signal
Module, and the disturbing signal generation module includes multiple direct digital frequency synthesier units, for passing through Direct Digital
The sampled value of frequency synthesis technique generation disturbing signal.
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