Methods, apparatus and electronic equipment for optical modulator bias control

Abstract

This application provides a method for bias control of an optical modulator, relating to the field of optical communication technology. The method includes: when the IQ modulator enters its operating mode, applying perturbation signals to the I-arm, Q-arm, and P-arm of the IQ modulator to obtain the signal light to be processed; performing low-pass filtering on the signal light to obtain an optical power feedback signal; calculating a decision ratio based on the optical power feedback signal; calculating the DC bias points of the I-arm, Q-arm, and P-arm based on the decision ratio; and controlling the I-arm, Q-arm, and P-arm based on each DC bias point. Based on the above method, the DC bias points of the three arms of the IQ modulator can be calculated and provided in real time, and each arm can be controlled according to the calculation results, ensuring the control accuracy of the system and realizing intelligent bias control of the IQ modulator.

Description

Technical Field

[0001] This application relates primarily to the field of optical communication technology, and in particular to methods, apparatus, and electronic devices for optical modulator bias control. Background Technology

[0002] As a key component in optical communication transmitters, optical modulators inherently possess nonlinear modulation characteristics, which are a major source of nonlinear distortion in the link. Besides improvements and optimizations to the device itself, most optical modulators require corresponding DC bias voltages for each DC arm to operate at the desired bias point, thereby improving parameters such as noise figure, gain, and dynamic range in the simulated optical link. Due to inherent defects in the lithium niobate material used to fabricate optical modulators, factors such as applied electric fields, temperature, and external forces can cause changes in the actual electric field applied to the lithium niobate crystal or its waveguide refractive index, which manifests as a shift in the modulator's DC operating bias point. This is the fundamental reason why related optical modulators (Mach-Zehnder modulators (MZM) and in-phase quadrature (IQ) modulators) require automatic bias control.

[0003] Currently, automatic bias control methods for lithium niobate optical modulators mainly include the DC power detection method and the control method based on external perturbation signals. The DC power method uses the DC component of the modulator's output optical power as the monitoring quantity for bias feedback control. This method has many limitations and poor accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a method, apparatus, and electronic device for optical modulator bias control, so as to solve the problem of poor accuracy in existing automatic bias control methods for optical modulators.

[0005] In a first aspect, the present invention provides a method for controlling the bias voltage of an optical modulator, the method comprising:

[0006] When the IQ modulator enters the working mode, a perturbation signal is applied to the I arm, Q arm and P arm of the IQ modulator to obtain the signal light to be processed, wherein the I arm, Q arm and P arm are different sub-modulators of the IQ modulator.

[0007] The optical signal light to be processed is low-pass filtered to obtain an optical power feedback signal;

[0008] The decision ratio is calculated based on the optical power feedback signal, wherein the decision ratio is the ratio of the fundamental frequency component to the second harmonic component of the optical power feedback signal, the fundamental frequency component is the amplitude of the optical power feedback signal at one frequency of the perturbation signal in the amplitude spectrum, and the second harmonic component is the amplitude of the amplitude at twice the frequency of the perturbation signal.

[0009] The DC bias points of the I-arm, Q-arm, and P-arm are calculated based on the decision ratio, and the I-arm, Q-arm, and P-arm are controlled based on each of the DC bias points.

[0010] Optionally, the DC bias point of the P-arm is set at the orthogonal point, and the perturbation signal is applied to the I-arm or the Q-arm, or the perturbation signal is applied to the P-arm, so that the AC component of the optical power feedback signal is represented as follows:

[0011] A cos(θcos(2πft)+θ bias )

[0012] Where A is a coefficient, θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied, f is the frequency of the perturbation signal, and θ bias It is the DC bias point of the arm to which the perturbation signal is applied.

[0013] Optionally, the method further includes determining the initial DC bias points of the I-arm, Q-arm, and P-arm respectively, and correcting the DC bias point calculated based on the decision ratio according to the initial DC bias points.

[0014] Optionally, the initial DC bias points of the I-arm, Q-arm, and P-arm are determined as follows: The perturbation signal is applied to the P-arm to obtain two P-arm DC bias points at 90° and 270° corresponding to the two local maximum values ​​of the decision ratio; when the P-arm is at the two P-arm DC bias points, the perturbation signal is applied to the I-arm, and the DC bias of the I-arm is adjusted to obtain two I-arm DC bias points corresponding to the two local minimum values ​​of the decision ratio; the perturbation signal of the I-arm is turned off, and while the perturbation signal is applied to the P-arm, the two I-arm DC bias points are determined to be 0° and 180° respectively based on the fundamental frequency component of the optical power feedback signal; when the P-arm is at the two P-arm DC bias points, the initial DC bias points of the Q-arm, Q-arm, and P-arm are determined as follows: The perturbation signal is applied to the Q-arm, and the DC bias of the Q-arm is adjusted to obtain two Q-arm DC bias points corresponding to the two local minimum values ​​of the decision ratio; the perturbation signal of the Q-arm is turned off, and with the perturbation signal applied to the P-arm, the two Q-arm DC bias points are determined to be 0° and 180° respectively according to the fundamental frequency component of the optical power feedback signal; the perturbation signal is applied to the P-arm, and the DC bias of the P-arm is adjusted to determine the two P-arm DC bias points of 0° and 180°; and the midpoint of the two P-arm DC bias points of 0° and 180° is determined to be the 90° P-arm DC bias point, and the other of the two P-arm DC bias points of 90° and 270° is the 270° P-arm DC bias point.

[0015] Iterative calculations ensure that the DC bias point of arms I and Q is 180° and the DC bias point of arm P is 90°, thus avoiding the ambiguity of the bias operating point controlled by arm P.

[0016] Optionally, the operating modes include: single-channel modulation mode, dual-channel modulation mode, and single-sideband modulation mode.

[0017] By biasing the optical IQ modulator, various modulation modes of optical signals can be achieved, including single-channel modulation, multi-channel modulation, and single-sideband modulation, which meets the conventional requirements of the communication modulation formats used in current space lasers.

[0018] Optionally, when the IQ modulator enters the single-path modulation mode or the dual-path modulation mode, the power expression of the signal light to be processed includes... The The maximum value of the carrier phase change introduced by the modulation signal applied to a certain arm is used to characterize the maximum value of the carrier phase change. The range of Δ is (-π / 4, 0) ∪ (0, π / 4).

[0019] Optionally, the single-path modulation mode specifically involves applying a communication modulation signal to the I arm of the IQ modulator, while not applying the communication modulation signal to the Q arm.

[0020] Optionally, the dual-path modulation mode specifically involves applying a communication modulation signal to both the I-arm and the Q-arm of the IQ modulator.

[0021] Optionally, the single-sideband modulation mode specifically involves applying sinusoidal signals with orthogonal phases and consistent amplitudes to both the I-arm and the Q-arm in the IQ modulator.

[0022] Optionally, when the IQ modulator enters the operating mode, applying a perturbation signal to any one of the I-arm, Q-arm, and P-arm of the IQ modulator includes: applying the perturbation signal to the P-arm when the IQ modulator enters the single-sideband modulation mode; or, applying the perturbation signal to the I-arm and locking the DC bias point of the P-arm at the quadrature point when the IQ modulator enters the single-sideband modulation mode; or, applying the perturbation signal to the Q-arm and locking the DC bias point of the P-arm at the quadrature point when the IQ modulator enters the single-sideband modulation mode.

[0023] Optionally, the expression for the decision ratio is:

[0024]

[0025] Where J1(·) is a first-order Bessel function of the first kind, J2(·) is a second-order Bessel function of the first kind, and -2Asin(θ) bias J1(θ) is the coefficient of the amplitude at one frequency of the perturbation signal in the amplitude spectrum, -2Acos(θ) bias J2(θ) is the coefficient of the amplitude at twice the frequency of the perturbation signal in the amplitude spectrum, where θ bias θ is the DC bias point of the arm to which the perturbation signal is applied, and θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied.

[0026] Optionally, the expressions for the DC bias points of the I-arm, the Q-arm, and the P-arm are:

[0027]

[0028] Where atan(·) is the arctangent function, and θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied.

[0029] Optionally, the step of calculating the decision ratio based on the optical power feedback signal conversion includes: performing a Fast Fourier Transform (FFT) on the optical power feedback signal, and calculating the ratio of the amplitude at one frequency of the perturbation signal to the amplitude at two frequencies of the perturbation signal in the transformed amplitude spectrum.

[0030] Optionally, after calculating the DC bias points of the I-arm, Q-arm, and P-arm based on the decision ratio, the method further includes: sampling multiple sets of signals at their respective corresponding DC bias points at equal time intervals, and calculating the standard deviation of the real-time DC bias points of the multiple sets of signals; determining whether the standard deviation is less than a set threshold; if the standard deviation is less than or equal to the set threshold, maintaining the integration time of the FFT; if the standard deviation is greater than the set threshold, increasing the integration time of the FFT, adjusting the frequency of the perturbation signal, or increasing the peak-to-peak value of the perturbation signal, wherein the peak-to-peak value does not exceed 10% of the half-wave voltage of the arm to which the perturbation signal is applied.

[0031] During bias control, the change in the bias points of the three arms can cause the detector output feedback signal to be weak, that is, the peak-to-peak value of the feedback signal is small. By increasing the FFT integration time, the signal-to-noise ratio of the feedback signal can be guaranteed when the feedback optical signal is weak, thereby maintaining the bias control accuracy of each DC arm of the optical IQ modulator at a high level.

[0032] Optionally, applying a perturbation signal to the I-arm, Q-arm, and P-arm of the IQ modulator to obtain the signal light to be processed includes: applying a perturbation signal to any one of the I-arm, Q-arm, and P-arm of the IQ modulator to obtain the signal light to be processed.

[0033] In a second aspect, the present invention provides an optical modulator bias control system, the system comprising:

[0034] An IQ modulator is used to modulate input light. The IQ modulator includes an I-arm, a Q-arm, and a P-arm, which are different sub-modulators of the IQ modulator.

[0035] A beam splitter is used to distribute the output light of the IQ modulator to the feedback detector according to a preset ratio.

[0036] A feedback detector is used to perform low-pass filtering on the signal light distributed by the beam splitter to obtain an optical power feedback signal.

[0037] An analog-to-digital converter is used to perform analog-to-digital conversion on the optical power feedback signal output by the feedback detector.

[0038] The digital signal processing and decision module is used to perform a fast Fourier transform (FFT) on the optical power feedback signal after analog-to-digital conversion, and to calculate the DC bias points corresponding to the I arm, the Q arm, and the P arm.

[0039] A first digital-to-analog converter is used to control the DC bias point of the P-arm;

[0040] The second digital-to-analog converter is used to control the DC bias point of the I-arm;

[0041] The third digital-to-analog converter is used to control the DC bias point of the Q arm.

[0042] Thirdly, the present invention provides an optical communication transmitter, the optical communication transmitter comprising: an optical modulator bias control system;

[0043] The optical modulator bias control system is used to implement the optical modulator bias control method steps described above.

[0044] Fourthly, the present invention provides an electronic device, which includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus;

[0045] Memory, used to store computer programs;

[0046] When a processor executes a program stored in memory, it implements any of the methods described in the first aspect above.

[0047] Fifthly, the present invention provides a computer-readable storage medium storing a computer program therein, which, when executed by a processor, implements any of the methods described in the first aspect above.

[0048] Beneficial effects of the embodiments in this application:

[0049] The method provided in this application can calculate and provide the DC bias points of the I, Q, and P arms of an IQ modulator in real time, and control each arm according to the calculation results, ensuring the control accuracy of the system and realizing intelligent biasing of the IQ modulator. In this embodiment, the DC bias points for controlling each arm are calculated using the low-pass filtered optical power feedback signal from a low-bandwidth feedback detector, achieving multi-body compatibility of the optical IQ modulator.

[0050] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0052] Figure 1 A schematic diagram of an optical modulator bias control system provided in this application;

[0053] Figure 2 A flowchart of a method for controlling the bias voltage of an optical modulator provided in this application;

[0054] Figure 3 The relationship between the decision ratio and the DC bias point is provided in this application;

[0055] Figure 4 A comparison diagram of the calculated DC bias point and the actual DC bias point provided for this application;

[0056] Figure 5 A graph showing the relationship between the calculated standard deviation and the number of FFT calculation points provided in this application;

[0057] Figure 6 A schematic diagram of the structure of an electronic device provided in this application. Detailed Implementation

[0058] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0059] Furthermore, in the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0060] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0061] See Figure 1This is a schematic diagram of the optical modulator bias control system provided in an embodiment of this application. The system 100 includes: a laser 101, an IQ modulator 102, a beam splitter 103, a feedback detector (FD) 104, an analog-to-digital converter (ADC) 105, a digital signal processing and decision module 106, a first digital-to-analog converter 107, a second digital-to-analog converter 108, and a third digital-to-analog converter 109. The IQ modulator can be considered as consisting of three sub-modulators: MZMI, MZMQ, and MZMP. Each of these requires corresponding DC bias control for the IQ modulator 102 to function properly. For ease of description, these three sub-modulators are referred to as the I-arm, Q-arm, and P-arm, respectively. The output light of the laser 101 is connected to the input of the IQ modulator 102, and the output of the IQ modulator 102 is connected to the beam splitter 103, distributing the light between the output and feedback in a certain proportion. For example, the beam splitter 103 uses 95% of the optical energy as the modulation signal light output by the transmitting system, and the remaining 5% of the optical energy enters the feedback detector 104 for changes in output optical power. The output of the feedback detector 104 is acquired by the analog-to-digital converter 105 and processed. In one embodiment, the output of the feedback detector 104 is DC-coupled. In the digital signal processing and decision module 106, the digital signal processing module is mainly responsible for performing the FFT calculation and calculating the DC bias point of each arm in real time using the amplitude spectrum calculated by the FFT. The decision module mainly adjusts the DC bias, the frequency and peak-to-peak value of the applied perturbation signal, and the integration time of the FFT calculation in real time based on the calculated value of the DC bias point of each arm to ensure high control accuracy. The decision module controls the first digital-to-analog converter 107, the second digital-to-analog converter 108, and the third digital-to-analog converter 109 to control the DC bias points of the P arm, I arm, and Q arm of the IQ modulator, respectively. The output of each digital-to-analog converter 107-109 includes two parts: DC bias voltage and perturbation signal. The peak-to-peak value of the applied perturbation signal does not exceed 10% of the half-wave voltage of the IQ modulator 102 used.

[0062] Based on the aforementioned optical modulator bias control system 100, this application embodiment provides a method for optical modulator bias control, such as... Figure 2 The diagram shown illustrates the process of this method, which may include the following steps:

[0063] Step 201: When the IQ modulator enters the working mode, apply perturbation signals to the I-arm, Q-arm, and P-arm of the IQ modulator to obtain the signal light to be processed;

[0064] Step 202: Perform low-pass filtering on the signal light to be processed to obtain the optical power feedback signal;

[0065] In this embodiment, the applied perturbation signal is a sinusoidal signal, and the operating mode may include, but is not limited to, single-channel modulation mode, dual-channel modulation mode, and single-sideband modulation mode. Different operating modes present various operating conditions, which are described in detail below. It should be noted that applying a perturbation signal to the I-arm, Q-arm, and P-arm of the I-Q modulator specifically means applying a perturbation signal to one of the I-arm, Q-arm, or P-arm at a certain moment.

[0066] Operating Mode 1: Single-channel modulation mode

[0067] The single-channel modulation mode means that the IQ modulator applies the communication modulation signal to only one channel, and the communication modulation signal is mainly a bipolar non-return-to-zero code. The reason for discussing this operating mode is that, under this condition, the IQ modulator can implement OOK (On-Off Keying) and BPSK (Binary Phase Shift Keying) modulation. This application's embodiments use the application of the communication modulation signal to the I-arm as an example. There are three operating conditions in this mode.

[0068] Operating Condition 1: A modulation signal is applied to the I-arm, but no modulation signal is applied to the Q-arm. A perturbation signal, such as a sinusoidal signal, is applied to the I-arm. Under this condition, the power of the light output from the IQ modulator 102 (i.e., the signal light to be processed) can be expressed as follows:

[0069]

[0070] Among them, P in m is the input optical power to the IQ modulator. I (t) represents the I-channel communication signal and m I (t) = ±1, The maximum value of the communication modulation signal applied to the I-arm with respect to the carrier phase change is defined in the range (0, π / 2], θ. Ibias-dc θ Qbias-dc θ IQbisa-dc The phase shifts θ are caused by the DC bias of the three arms of the IQ modulator, respectively. dI is the ratio of half the peak-to-peak value of the perturbation signal applied to arm I to the half-wave voltage of arm I, where f is the frequency of the applied perturbation signal.

[0072] The low-pass filter of detector 104 generates the required optical power feedback signal. As long as Δ≠0, this application can complete the DC bias control required for each modulation format of IQ modulator 102. Under this condition, the optical power feedback signal obtained after the signal light output from IQ modulator 102 passes through the low-pass filter of low-bandwidth feedback detector 104 can be written as follows:

[0073]

[0074] Operating Condition 2: A modulation signal is applied to the I-arm, but no modulation signal is applied to the Q-arm. A perturbation signal is applied to the Q-arm. Under this condition, the optical power output of the IQ modulator 102 can be written as follows:

[0075]

[0076] Where, θ dQ This is the ratio of half the peak-to-peak value of the perturbation signal applied to the Q-arm to the half-wave voltage of the Q-arm. Under this condition, the optical power feedback signal obtained after the signal light output from the IQ modulator 102 passes through the low-pass filter of the low-bandwidth feedback detector 104 can be written as follows:

[0077]

[0078] Operating condition 3: Modulation signal applied to I arm, no modulation signal applied to Q arm, and perturbation signal applied to P arm. Under this condition, the optical power output of IQ modulator 102 can be written as follows:

[0079]

[0080] Where, θ dIQ This is the ratio of half the peak-to-peak value of the perturbation signal applied to the P-arm to the half-wave voltage of the P-arm. Under this condition, the optical power feedback signal obtained after the signal light output from the IQ modulator 102 passes through the low-pass filter of the low-bandwidth feedback detector 104 can be written as follows:

[0081]

[0082] The above three operating conditions describe the use of the optical IQ modulator 102 for OOK or BPSK modulation, where only one communication modulation signal is applied to the I channel. After the optical power signal passes through the low-pass filter of the low-bandwidth feedback detector 104, it is easy to see that the signal modulation term m in the formula... I (t) are all eliminated.

[0083] Operating Mode 2: Dual-channel modulation mode

[0084] In single-channel modulation mode, the IQ modulator applies communication modulation signals through both channels. The communication modulation signals are primarily bipolar non-return-to-zero (NRZ) codes. The amplitudes of the communication modulation signals applied to the I and Q arms are consistent with those described earlier, with identical signs and amplitudes. When the codewords are completely identical, it is BPSK modulation; when the codewords are not completely identical, it is QPSK modulation. Essentially, both are QPSK modulation. This mode has the following three operating conditions.

[0085] Operating Condition 4: Modulation signal applied to I-arm, modulation signal applied to Q-arm, and perturbation signal applied to I-arm. Under this condition, the optical power (signal light to be processed) output by IQ modulator 102 can be written as follows:

[0086]

[0087] Where, m Q (t) is the Q-channel communication signal and m Q (t) = ±1, The maximum value of the communication modulation signal applied to the Q-arm with respect to the carrier phase change is required. And the range of Δ is (-π / 4, 0) ∪ (0, π / 4). After low-pass filtering by the low-bandwidth feedback detector 104, the optical power feedback signal is obtained, which can be written as follows:

[0088]

[0089] Operating condition 5: Modulation signal applied to I-arm, modulation signal applied to Q-arm, and perturbation signal applied to Q-arm. Under this condition, the optical power output of the IQ modulator 102 can be expressed as follows:

[0090]

[0091] After low-pass filtering by the low-bandwidth feedback detector 104, the resulting optical power feedback signal can be expressed as follows:

[0092]

[0093] Operating Condition 6: Modulation signal applied to I arm, modulation signal applied to Q arm, and perturbation signal applied to P arm. Under this condition, the optical power output of IQ modulator 102 can be expressed as follows:

[0094]

[0095] After low-pass filtering by the low-bandwidth feedback detector 104, the resulting optical power feedback signal can be expressed as follows:

[0096]

[0097] Based on the optical power signal output after low-pass filtering by the low-bandwidth feedback detector 104 in operating conditions 4, 5, and 6, the signal modulation term m in the formula can be seen. I (t), m Q (t) are all eliminated. The voltage signal output by the feedback detector 104 is equal to the optical power multiplied by the responsivity of the feedback detector 104 and then multiplied by the detector transimpedance, thus exhibiting a linear relationship. In both cases above, whether dual-channel or single-channel modulation is applied, the applied signal to the IQ modulator 102 is a digital binary signal.

[0098] Operating Mode 3: Single Sideband Modulation Mode

[0099] Single-sideband modulation mode involves applying sinusoidal signals with orthogonal phases and consistent amplitudes to both channels of the IQ modulator. This mode has the following three operating conditions.

[0100] Operating Condition 7: When sinusoidal signals with orthogonal phase and consistent amplitude are applied to the I and Q arms, and a perturbation signal is applied to the P arm, the optical power output of the IQ modulator 102 at this time can be written as follows:

[0101]

[0102] Where 'a' represents half the peak-to-peak value of the applied RF signal. In single-sideband modulation, to ensure the side-mode rejection ratio of the output optical signal, the peak-to-peak value of the applied RF signal is generally relatively small. rf The frequency of the applied radio frequency signal (i.e., the sinusoidal signal mentioned above) is given by the condition f. rf This is much greater than the frequency f of the perturbation signal and the detection bandwidth of the feedback detector 104. After low-pass filtering by the low-bandwidth feedback detector 104, the resulting optical power feedback signal can be expressed as follows:

[0103]

[0104] Where J0(·) is the zeroth-order Bessel function of the first kind.

[0105] Operating Condition 8: Sinusoidal signals with orthogonal phase and consistent amplitude are applied to both arms I and Q, and a perturbation signal is applied to arm I. Under this condition, the output optical power of the IQ modulator 102 is written as follows:

[0106]

[0107] When the bias point of the P-arm is the orthogonal point, i.e., the DC offset phase is π / 2, the above equation can be written as follows after low-pass filtering by a low-bandwidth detector:

[0108]

[0109] Operating condition 9: Sinusoidal signals with orthogonal phase and consistent amplitude are applied to the I and Q arms, and a perturbation signal is applied to the Q arm. Under this condition, the output optical power of the IQ modulator 102 is written as follows:

[0110]

[0111] When the bias point of the P-arm is the orthogonal point, that is, when the DC offset phase is π / 2, the above equation can be written as follows after low-pass filtering by the low-bandwidth feedback detector 102:

[0112]

[0113] Based on the above three working modes and nine operating conditions, it is easy to see that by setting the DC bias point of the P-arm at the quadrature point and adding a perturbation signal to the I-arm or Q-arm, or by adding a perturbation signal to the P-arm, after low-pass filtering by the low-bandwidth feedback detector 104, the AC component of the optical power feedback signal becomes as follows:

[0114] A cos(θcos(2πft)+θ bias )

[0115] Where A is a coefficient, θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied, f is the frequency of the perturbation signal, and θ biss It is the DC bias point of the arm to which the perturbation signal is applied.

[0116] Step 203: Calculate the decision ratio based on the optical power feedback signal;

[0117] In this embodiment, the optical power signal output by the feedback detector 104 is processed using FFT, and the decision ratio is used as the basis for bias control to complete the automatic control of the three arms of the IQ modulator 102 under different modulation formats. The decision ratio is the ratio of the amplitude at one times the perturbation signal frequency to the amplitude at two times the perturbation signal frequency in the amplitude spectrum of the optical power feedback signal. For ease of description, the amplitude at one times the perturbation signal frequency in the amplitude spectrum is referred to as the fundamental frequency component, and the amplitude at two times the perturbation signal frequency is referred to as the second harmonic component.

[0118] As mentioned above, A cos(θcos(2πft)+θ bias () is the general expression for the AC component of the optical power feedback signal, where the coefficient A may be positive or negative under different conditions. This AC signal can be written using a Bessel expansion as follows:

[0119] Acos(θcos(2πft)+θ bias )≈Acos(θ bias )J0(θ)

[0120] -2Acos(θ bias J2(θ)cos(4πft)

[0121] -2Asin(θ bias J1(θ)cos(2πft)

[0122] Where J1(·) is a first-order Bessel function of the first kind, and J2(·) is a second-order Bessel function of the first kind. From the above equation, it can be seen that the coefficient of the fundamental frequency component is -2Asin(θ). bias The coefficient of the second harmonic component is -2Acos(θ). biasIn the amplitude spectrum calculated by FFT, the absolute values ​​of the amplitudes of the fundamental frequency component and the second harmonic component can be obtained separately. Therefore, the ratio between them can be calculated. This ratio is called the decision ratio, denoted as rate, and its expression is as follows:

[0123]

[0124] Where, θ bias It is the DC bias point of the arm to which the perturbation signal is applied, and θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied.

[0125] Step 204: Calculate the DC bias points corresponding to I-arm, Q-arm, and P-arm based on the decision ratio, and control each arm based on each DC bias point.

[0126] The specific formulas for calculating the DC bias points corresponding to the I-arm, Q-arm, and P-arm based on the above decision ratios are as follows:

[0127]

[0128] Where atan(·) is the arctangent function, and θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied. In this application, the peak-to-peak value of the applied perturbation signal is known, and the half-wave voltage of each arm of the modulator can be obtained in the time slot when each arm is controlled separately, so the value of θ can be accurately calculated.

[0129] Taking the P-arm as an example, under the above three operating modes and when a perturbation signal is applied to the P-arm, in an ideal situation, the relationship between the ratio of the fundamental frequency component to the second harmonic component in the optical power feedback signal and the P-arm bias point is as follows: Figure 3 As shown. When the P-arm is locked at the orthogonal point (bias point is 90° or 270°), the relationship between the decision ratio and the corresponding bias point when a perturbation signal is applied to the I-arm or Q-arm is also as follows. Figure 3 As shown. Therefore, the criteria for controlling different DC arms of the IQ modulator 102 are completely consistent in this application.

[0130] For example, the comparison between the P-arm bias point position calculated using the above DC bias point calculation formula and the actual bias point position is as follows: Figure 4 As shown. According to Figure 4 There is a conversion relationship between the calculated bias point value and the actual bias point. This is mainly because the fundamental frequency component and the second harmonic component are both positive after amplitude spectrum modulus extraction; therefore, the calculated arctangent value has a range of (0, π / 2). Thus, a crucial factor is how each arm determines the four key bias positions: 0°, 90°, 180°, and 270°. This will be discussed in more detail below.

[0131] according to Figure 3 It is known that when a perturbation signal is applied to the P-arm, the DC bias point is either 90° or 270° when the P-arm is at the orthogonal point. At this point, the exact location of the DC bias point cannot be determined because the positions of the DC bias points of the I-arm and Q-arm are uncertain. Therefore, the first step is to adjust the P-arm bias point by applying a perturbation signal to the P-arm and obtaining the two local maximum values ​​of the decision ratio (e.g., ...). Figure 3 The two upper apexes shown correspond to the 90° and 270° DC bias points of the P-arm. The second step involves applying a perturbation signal to the I-arm and adjusting its DC bias, when the P-arm is at one of the two DC bias points. This constitutes a DC bias voltage scan process, during which the local minimum of two adjacent decision ratios is sought (e.g., ...). Figure 3 The two DC bias points (shown at their lower tips) are the two DC bias points of the I-arm. When the I-arm perturbation signal is turned off at these two points, and a perturbation signal is applied to the P-arm, the fundamental frequency components of the feedback signals at these two points in the I-arm are calculated. The point with the smaller fundamental frequency component is the 180° bias point of the I-arm, which is the bias point required by the IQ modulator. Conversely, the point with the larger fundamental frequency component is the 0° bias point of the I-arm.

[0132] It should be noted that this application applies a perturbation signal to only one of the three arms (I, Q, P) at any given time. The fundamental frequency component, second harmonic component, and decision ratio calculated at this time are all for their respective arms.

[0133] After determining that the I-arm is controlled near the 0° point, the P-arm is adjusted back to its previous DC bias voltage. A perturbation signal is applied to the Q-arm, and the DC bias voltage of the Q-arm is adjusted to obtain the two Q-arm DC bias voltage points corresponding to the two local minimum values ​​of the decision ratio. The perturbation signal of the Q-arm is turned off, and with the perturbation signal applied to the P-arm, the two Q-arm DC bias voltage points are determined to be 0° and 180° respectively based on the fundamental frequency component of the optical power feedback signal. This application applies the same control and calculation process to the Q-arm and I-arm, thereby determining that both the I-arm and Q-arm are near the 0° DC bias voltage point, and the P-arm is at the 90° or 270° DC bias voltage point. At this time, a perturbation signal is applied to the P-arm, and the DC bias voltage of the P-arm is adjusted to confirm the two DC bias voltage points of the P-arm at 0° and 180° (the optical power feedback signal has the highest DC component at the 0° DC bias voltage point, and the optical power feedback signal has the lowest DC component at the 180° bias voltage point). The midpoint of these two voltages is the determined 90° DC bias voltage point of the P-arm.

[0134] It is worth noting that the feedback detector output used is DC-coupled. When resolving the DC bias point of the P-arm to 90° and 270°, the DC power component needs to be used as a basis because it is already determined that the DC bias points of the I-arm and Q-arm are both near the 0° point. However, when resolving the 0° and 180° points of the I-arm and Q-arm, DC power is neither necessary nor acceptable as a criterion. This is because, taking QPSK as an example, when the peak-to-peak value of the applied RF modulation signal is greater than the modulator half-wave voltage, and the DC bias point of the I-arm and Q-arm is controlled at the 180° point, the optical power feedback signal has the highest DC power level. Conversely, when the peak-to-peak value of the applied RF modulation signal is less than the modulator half-wave voltage, and the DC bias point of the I-arm and Q-arm is controlled at the 180° point, the optical power feedback signal has the lowest DC power level. After determining the 0°, 90°, 180°, and 270° points for arm P, the corresponding 90° and 270° points can be determined based on the positions of arms I and Q at their 0° and 180° points, respectively. Once arm P is locked at the 90° point, the bias points of arms I and Q are adjusted to be near the 180° point. After determining the initial DC bias points of I, Q, and P, the following steps can be taken... Figure 4 The calculated real-time DC bias positions for each arm are given. The following four cases are discussed: When the actual bias point is between 0° and 90°, the actual bias point equals the calculated bias point; when the actual bias point is between 90° and 180°, the actual bias point equals the 180° bias point minus the calculated bias point; when the actual bias point is between 180° and 270°, the actual bias point equals the 180° bias point plus the calculated bias point; when the actual bias point is between 270° and 360°, the actual bias point equals the 360° bias point minus the calculated bias point.

[0135] Currently, the control principle of the bias control board of commercial optical IQ modulators is only responsible for controlling the DC bias point of the P-arm at the quadrature point. It cannot determine whether to control it at 90° or 270° (in previous IQ modulators, the P-arm would sometimes lock at 90° and sometimes at 270°, which would cause some problems in use, such as single-sideband modulation). After the above processing, the bias point of the P-arm can be determined to be controlled at 90°, thus greatly increasing the robustness of the control. It is worth mentioning that in the above process, the half-wave voltage of the P-arm is the difference between the voltages corresponding to the local maximum values ​​of the two decision ratios, while the half-wave voltages of the I-arm and Q-arm are the difference between the voltages corresponding to the local minimum values ​​of their respective two decision ratios. That is, the half-wave voltages of the three arms of the IQ modulator are also determined in this process. The above process is essentially a process of determining the initial state of an IQ modulator and calculating the half-wave voltage. Iterative measurement and decision-making can ensure that the DC bias points of the I arm and Q arm are both at 180° and the DC bias point of the P arm is at 90°.

[0136] The subsequent step involves performing a local optimum algorithm to calculate the decision ratio of each arm in real time across time slots and inversely determine the corresponding DC bias point, ensuring stable control of the bias points of each arm of the IQ modulator over a long period. Therefore, based on the above analysis, a key robustness of this application lies in its adaptability to a very wide range of RF modulation signals. As long as the peak-to-peak value of the applied RF signal is between 0 and 2 times the modulator's half-wave voltage and theoretically not equal to the modulator's half-wave voltage, this application can achieve the required bias point control for the modulator. Since the I and Q arms can be locked at any position through bias position calculation after the P arm is locked at the 90° point, various modulation formats can be implemented. For example, the implementation of OOK: I-channel adds a communication modulation signal, I-arm is locked at 90°, Q-arm is locked at 180°, and P-arm is locked at 90°; the implementation of BPSK: I-channel adds a communication modulation signal, I-arm is locked at 180°, Q-arm is locked at 180°, and P-arm is locked at 90°; the implementation of QPSK: I-channel adds a communication modulation signal, Q-channel adds a communication modulation signal, I-arm is locked at 180°, Q-arm is locked at 180°, and P-arm is locked at 90°; the implementation of single-sideband modulation: I-channel adds a sine modulation signal, Q-channel adds a cosine modulation signal, I-arm is locked at 180°, Q-arm is locked at 180°, and P-arm is locked at 90°.

[0137] Furthermore, this application can effectively improve the signal-to-noise ratio of the optical power feedback signal by appropriately improving the frequency and amplitude of the added perturbation signal and increasing the integration time of the FFT.

[0138] When the incident optical power of the IQ modulator is constant, applying a perturbation signal to the P-arm results in a monotonically decreasing peak-to-peak value of the AC component of the optical power feedback signal as the peak-to-peak value of the applied communication modulation signal monotonically increases from 0 to twice the modulator half-wave voltage. This AC component is precisely what we need to extract the decision ratio. When the DC bias point of the P-arm is controlled after the quadrature point and the incident optical power of the IQ modulator is constant, applying a perturbation signal to the I-arm or Q-arm results in a monotonically decreasing peak-to-peak value of the AC component of the optical power feedback signal as the peak-to-peak value of the applied RF signal gets closer to the modulator half-wave voltage. Therefore, without knowing the peak-to-peak value of the applied RF signal, applying perturbation signals to each arm can result in a low signal-to-noise ratio in the optical power feedback signal, which may weaken the accuracy of the bias control for each arm. Therefore, the signal-to-noise ratio of the detection can be improved by appropriately adjusting the frequency of the perturbation signal and increasing the peak-to-peak value of the perturbation signal (maximum not exceeding 10% of the half-wave voltage).

[0139] This application primarily employs an increased FFT integration time to ensure the DC bias control accuracy of each arm when the optical power feedback signal is weak. Specifically, multiple sets of signals are sampled at the corresponding DC bias points of the I, Q, and P arms at equal time intervals, and the standard deviation of the real-time DC bias points of these multiple sets of signals is calculated. It is then determined whether this standard deviation is less than a set threshold. If the standard deviation is less than the set threshold, the FFT integration time is reduced; if the standard deviation is equal to the set threshold, the FFT integration time is maintained; if the standard deviation is greater than the set threshold, the FFT integration time is increased, or the frequency of the perturbation signal is adjusted, or the peak-to-peak value of the perturbation signal is increased, but the peak-to-peak value of the perturbation signal cannot exceed 10% of the half-wave voltage of the arm to which the perturbation signal is applied.

[0140] Taking the P-arm as an example, the signal-to-noise ratio of the optical power feedback signal is set to 20dB, the actual range of the bias point is 90° to 270°, the peak-to-peak value of the perturbation signal is set to 0.1 times the modulator half-wave voltage, the frequency of the perturbation signal is 25kHz, and the sampling rate is set to 500kHz in the simulation. The relationship between the final calculation error standard deviation and the number of FFT calculation points is as follows. Figure 5 As shown. From Figure 5 It is easy to see that increasing the number of FFT calculation points can reduce the standard deviation of the calculation error, thereby improving the accuracy of the bias control of each arm. When the sampling rate remains unchanged, increasing the number of FFT calculation points means increasing the integration time.

[0141] The method provided in this application can calculate and provide the DC bias points of the three arms of the IQ modulator in real time. Based on the calculation results, the integration time of the FFT calculation can be adjusted in real time to ensure the control accuracy of the system and achieve intelligent bias control of the IQ modulator. Furthermore, the method of this application is compatible with multiple modulation formats, including OOK, BPSK, QPSK, and single-sideband modulation, meeting the conventional requirements of communication modulation formats used in current space lasers. The wide range of peak-to-peak values ​​of the communication modulation signal in this application improves the robustness of the control system. Iterative calculations ensure that the DC bias points of the I and Q arms are 180° and the DC bias point of the P arm is 90°, avoiding the ambiguity problem of the bias operating point for P arm control.

[0142] Based on the same inventive concept, this application also provides an optical modulator bias control system, see [link to relevant documentation]. Figure 1 As shown, the system includes:

[0143] IQ modulator 102 is used to modulate input light, wherein the IQ modulator includes an I-arm, a Q-arm, and a P-arm, and the I-arm, Q-arm, and P-arm are different sub-modulators of the IQ modulator;

[0144] The beam splitter 103 is used to distribute the output light of the IQ modulator 102 to the feedback detector according to a preset ratio.

[0145] Feedback detector 104 is used to perform low-pass filtering on the signal light distributed by beam splitter 103 to obtain optical power feedback signal;

[0146] Analog-to-digital converter 105 is used to perform analog-to-digital conversion on the optical power feedback signal output by feedback detector 104;

[0147] The digital signal processing and decision module 106 is used to perform a fast Fourier transform (FFT) on the optical power feedback signal after analog-to-digital conversion, and to calculate the DC bias points corresponding to the I arm, the Q arm and the P arm respectively.

[0148] The first digital-to-analog converter 107 is used to control the DC bias point of the P arm;

[0149] The second digital-to-analog converter 108 is used to control the DC bias point of the I-arm;

[0150] The third digital-to-analog converter 109 is used to control the DC bias point of the Q arm.

[0151] Based on the same inventive concept, this application also provides an electronic device, such as... Figure 6 As shown, the system includes a processor 601, a communication interface 602, a memory 603, and a communication bus 604. The processor 601, communication interface 602, and memory 603 communicate with each other via the communication bus 604. The memory 603 stores computer programs. When the processor 601 executes the program stored in the memory 603, it implements the optical modulator bias control method steps described in the previous embodiments to achieve the same technical effect.

[0152] The communication bus mentioned in the above electronic devices can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not indicate that there is only one bus or one type of bus.

[0153] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0154] The memory may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0155] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0156] In another embodiment provided in this application, a computer-readable storage medium is also provided, which stores a computer program. When the computer program is executed by a processor, it implements the method steps of any of the above-described optical modulator bias control methods to achieve the same technical effect.

[0157] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute any of the above-described optical modulator bias control method steps to achieve the same technical effect.

[0158] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means.

[0159] The data center performs the transmission. The computer-readable storage medium can be any available medium that a computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives (SSDs)).

[0160] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0161] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system, device, electronic device, storage medium, and program product embodiments are basically similar to the method embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0162] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A method for bias control of an optical modulator, characterized in that, The method includes: When the IQ modulator enters the working mode, a perturbation signal is applied to the I arm, Q arm and P arm of the IQ modulator to obtain the signal light to be processed, wherein the I arm, Q arm and P arm are different sub-modulators of the IQ modulator. The optical signal light to be processed is low-pass filtered to obtain an optical power feedback signal; The decision ratio is calculated based on the optical power feedback signal, wherein the decision ratio is the ratio of the fundamental frequency component to the second harmonic component of the optical power feedback signal, the fundamental frequency component is the amplitude of the optical power feedback signal at one frequency of the perturbation signal in the amplitude spectrum, and the second harmonic component is the amplitude of the amplitude at twice the frequency of the perturbation signal. The DC bias points of the I-arm, Q-arm, and P-arm are calculated based on the decision ratio, and the I-arm, Q-arm, and P-arm are controlled based on each of the DC bias points.

2. The method as described in claim 1, characterized in that, By setting the DC bias point of the P-arm at the quadrature point and applying the perturbation signal to the I-arm or the Q-arm, or by applying the perturbation signal to the P-arm, the AC component of the optical power feedback signal is expressed as follows: A cos(θcos(2πft)+θ bias ) Where A is a coefficient, θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied, f is the frequency of the perturbation signal, and θ bias It is the DC bias point of the arm to which the perturbation signal is applied.

3. The method as described in claim 1, characterized in that, It also includes determining the initial DC bias points of the I-arm, Q-arm, and P-arm respectively, and correcting the DC bias point calculated based on the decision ratio according to the initial DC bias points.

4. The method as described in claim 3, characterized in that, The initial DC bias points of the I-arm, Q-arm, and P-arm are determined as follows: By applying the perturbation signal to the P-arm, two DC bias points of the P-arm corresponding to the two local maximum values ​​of the decision ratio are obtained at 90° and 270°. When the P-arm is at one of the two P-arm DC bias points, the perturbation signal is applied to the I-arm, and the DC bias of the I-arm is adjusted to obtain the two I-arm DC bias points corresponding to the two local minimum values ​​of the decision ratio. The perturbation signal of the I-arm is turned off, and when the perturbation signal is applied to the P-arm, the DC bias points of the two I-arms are determined to be 0° and 180° respectively according to the fundamental frequency component of the optical power feedback signal. When the P-arm is at the two P-arm DC bias points, the perturbation signal is applied to the Q-arm, and the DC bias of the Q-arm is adjusted to obtain the two Q-arm DC bias points corresponding to the two local minimum values ​​of the decision ratio. The perturbation signal of the Q arm is turned off, and when the perturbation signal is applied to the P arm, the DC bias points of the two Q arms are determined to be 0° and 180° respectively according to the fundamental frequency component of the optical power feedback signal. The perturbation signal is applied to the P-arm, and the DC bias voltage of the P-arm is adjusted to determine the two DC bias voltage points of the P-arm at 0° and 180°. as well as The midpoint between the 0° and 180° DC bias points of the P-arm is determined to be the 90° DC bias point of the P-arm, and the other of the 90° and 270° DC bias points is the 270° DC bias point of the P-arm.

5. The method as described in claim 1, characterized in that, The operating modes include: single-channel modulation mode, dual-channel modulation mode, and single-sideband modulation mode.

6. The method as described in claim 5, characterized in that, It also includes, when the IQ modulator enters the single-path modulation mode or the dual-path modulation mode, the power expression of the signal light to be processed includes... The The maximum value of the carrier phase change introduced by the modulation signal applied to a certain arm is used to characterize the maximum value of the carrier phase change. The range of Δ is (-π / 4, 0) ∪ (0, π / 4).

7. The method as described in claim 5, characterized in that, The single-channel modulation mode is specifically as follows: A communication modulation signal is applied to the I arm of the IQ modulator, but no communication modulation signal is applied to the Q arm.

8. The method as described in claim 5, characterized in that, The dual-path modulation mode is specifically as follows: A communication modulation signal is applied to both the I-arm and the Q-arm in the IQ modulator.

9. The method as described in claim 5, characterized in that, The single-sideband modulation mode is specifically as follows: A sinusoidal signal with orthogonal phase and consistent amplitude is applied to both the I-arm and the Q-arm in the IQ modulator.

10. The method as described in claim 9, characterized in that, When the IQ modulator enters the operating mode, applying a perturbation signal to any one of the I-arm, Q-arm, and P-arm of the IQ modulator includes: When the IQ modulator enters the single-sideband modulation mode, the perturbation signal is applied to the P-arm; or, When the IQ modulator enters the single-sideband modulation mode, the perturbation signal is applied to the I-arm, and the DC bias point of the P-arm is locked at the quadrature point; or, When the IQ modulator enters the single-sideband modulation mode, the perturbation signal is applied to the Q arm, and the DC bias point of the P arm is locked at the quadrature point.

11. The method as described in claim 1, characterized in that, The expression for the decision ratio is: Where J1(·) is a first-order Bessel function of the first kind, J2(·) is a second-order Bessel function of the first kind, and -2Asin(θ) bias J1(θ) is the coefficient of the amplitude at one frequency of the perturbation signal in the amplitude spectrum, -2Acos(θ) bias J2(θ) is the coefficient of the amplitude at twice the frequency of the perturbation signal in the amplitude spectrum, where θ bias θ is the DC bias point of the arm to which the perturbation signal is applied, and θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied.

12. The method as described in claim 11, characterized in that, The expressions for the DC bias points of the I-arm, the Q-arm, and the P-arm are as follows: Where atan(·) is the arctangent function, and θ is the ratio of half the peak-to-peak value of the perturbation signal to the half-wave voltage of the arm to which the perturbation signal is applied.

13. The method as described in claim 1, characterized in that, The step of calculating the decision ratio based on the optical power feedback signal conversion includes: performing a Fast Fourier Transform (FFT) on the optical power feedback signal and calculating the ratio of the amplitude at one frequency of the perturbation signal to the amplitude at two frequencies of the perturbation signal in the transformed amplitude spectrum.

14. The method as described in claim 13, characterized in that, After calculating the DC bias points of the I-arm, Q-arm, and P-arm based on the decision ratio, the method further includes: At their respective corresponding DC bias points, multiple sets of signals are sampled at the same time interval, and the standard deviation of the real-time DC bias points of the multiple sets of signals is calculated. Determine whether the standard deviation is less than a set threshold; If the standard deviation is less than or equal to the set threshold, then the integration time of the FFT is maintained; If the standard deviation is greater than the set threshold, then the integration time of the FFT is increased, the frequency of the perturbation signal is adjusted, or the peak-to-peak value of the perturbation signal is increased, wherein the peak-to-peak value does not exceed 10% of the half-wave voltage of the arm to which the perturbation signal is applied.

15. The method as described in claim 1, characterized in that, The step of applying perturbation signals to the I-arm, Q-arm, and P-arm of the IQ modulator to obtain the signal light to be processed includes: A perturbation signal is applied to any one of the I-arm, Q-arm, and P-arm in the IQ modulator to obtain the signal light to be processed.

16. A bias control system for an optical modulator, characterized in that, The system includes: An IQ modulator is used to modulate input light. The IQ modulator includes an I-arm, a Q-arm, and a P-arm, which are different sub-modulators of the IQ modulator. A beam splitter is used to distribute the output light of the IQ modulator to the feedback detector according to a preset ratio. A feedback detector is used to perform low-pass filtering on the signal light distributed by the beam splitter to obtain an optical power feedback signal. An analog-to-digital converter is used to perform analog-to-digital conversion on the optical power feedback signal output by the feedback detector. The digital signal processing and decision module is used to perform a fast Fourier transform (FFT) on the optical power feedback signal after analog-to-digital conversion, and to calculate the DC bias points corresponding to the I arm, the Q arm, and the P arm. A first digital-to-analog converter is used to control the DC bias point of the P-arm; The second digital-to-analog converter is used to control the DC bias point of the I-arm; The third digital-to-analog converter is used to control the DC bias point of the Q arm.

17. An optical communication transmitter, characterized in that, The optical communication transmitter includes: an optical modulator bias control system; The optical modulator bias control system is used to implement the steps of the method described in any one of claims 1-15.

18. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus. The processor, communication interface, and memory communicate with each other through the communication bus. Memory, used to store computer programs; A processor, when executing a program stored in memory, implements the steps of the method described in any one of claims 1-15.

19. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the method described in any one of claims 1-15.

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