Control system and control method for locking bias working point of silicon-based chip of MZM structure

Abstract

The invention provides a control system for locking a bias working point of a silicon-based chip of an MZM structure, which comprises the silicon-based chip, two sampling circuits, an MCU control unit, a multi-channel operational amplifier and an upper computer, and is characterized in that the silicon-based chip comprises an MZM modulator, the MZM modulator comprises a modulation arm A, a modulation arm B, a heater, an A-arm photodiode and a B-arm photodiode, a sampling circuit collects voltage and current signals on a driving arm on the MZM modulator for feedback, the voltage and current signals are transmitted to a peripheral MCU control unit and uploaded to an upper computer, and the MCU control unit regulates and controls the voltage or current of a modulation arm A through a multi-channel operational amplifier. The invention further provides a control method of the control system for locking the bias working point of the silicon-based chip of the MZM structure. The occupied space in the high-speed optical module is small, so that the layout of other electric chips is facilitated, and higher circuit reliability is realized; a brand-new and accurate control method is designed.

Description

Technical Field

[0001] The present invention relates to the technical field of optical modulators, and particularly to a control system and a control method for locking the bias operating point of a silicon-based chip with an MZM structure. Background Art

[0002] With the explosive growth of 5G communication, data center, and cloud computing technologies, the demand for the bandwidth, power consumption, and transmission rate of optical communication systems has increased sharply. As a core component of the optical network, high-speed optical modules need to meet the rate requirements of 400G / 800G or even 1.6T, and at the same time, they need to consider low power consumption, small size, and high reliability. Silicon Photonics has become one of the core technical routes for high-speed optical modules due to its compatibility with CMOS processes, high integration, and low cost advantages.

[0003] The Mach-Zehnder Modulator (MZM) is a key device for realizing electro-optic modulation in silicon-based chips. It changes the refractive index of the optical waveguide through an electrical signal and converts the electrical signal into an optical signal. The performance of the MZM directly determines key indicators such as the modulation efficiency, linearity, and bit error rate (BER) of high-speed optical modules. To achieve high-quality signal modulation, the MZM modulator needs to work at a specific bias operating point (Quadrature Bias Point) to maximize the linear region and extinction ratio (ER) of the modulator.

[0004] However, the bias operating point of the MZM modulator is prone to drift due to the following factors: 1) Temperature fluctuations. The refractive index of silicon material is thermally sensitive, and changes in the ambient temperature cause changes in the refractive index of the waveguide; 2) Device aging. Under long-term operation, the material properties of the waveguide (such as carrier concentration, stress distribution, etc.) gradually degrade; 3) Drift of the driving voltage. The electrical parameters of the driving circuit (such as bias voltage, impedance matching, etc.) drift over time. If the bias point deviates from the optimal position, it will lead to signal distortion, a decrease in the extinction ratio, and an aggravation of non-linear effects, seriously reducing the performance of high-speed optical modules. Therefore, the technology for dynamically locking the bias operating point of the MZM modulator has become a key difficulty in the design of high-speed silicon optical modules.

[0005] The silicon-based Mach-Zehnder Modulator (MZM) is based on the plasma dispersion effect of silicon material. By applying a reverse bias voltage to the PN junctions on both sides of the waveguide, the carrier concentration (electrons and holes) is changed, thereby regulating the refractive index of the waveguide. The MZM usually consists of two symmetric Y-branch waveguides. The input optical signal is divided into two paths, and after phase modulation, they are recombined, and the output optical intensity is determined by the phase difference between the two arms:

[0006] Among them, is the phase difference between the two arms, which has a linear relationship with the driving voltage V.

[0007] The bias operating point of the MZM is usually selected at the quadrature point of the transmission curve (i.e., ), at this time the linearity of the modulator is the highest and the extinction ratio is the largest. If the bias point drifts to the non-linear region (such as peaks or valleys) due to factors such as temperature and aging, it will lead to signal distortion, eye diagram closure and increased bit error rate. Therefore, the technology of dynamically locking the bias operating point of the MZM will determine the core parameters of its modulation performance.

[0008] At present, there are mainly several methods for locking the bias operating point of the silicon-based chip with the MZM structure. The first solution is to use a programmable system on chip (PSoC) and a proportional-integral-derivative (PID) control method to achieve the purpose of the electro-optic modulator working at the optimal operating point, as described in patent CN105302019A. The peripheral control device consists of a photodetector, a controller, a voltage amplifier circuit, an adder circuit, an error comparator and a second-order low-pass filter circuit, which requires closed-loop control and occupies a large area in the high-speed optical module, and the structure is cumbersome. At the same time, the PID control method has high requirements for parameter adjustment. For this non-linear system, linearization processing is required to improve the control accuracy. The tracking accuracy of the bias voltage control of this solution is only 100 mV, and it is also sensitive to external interference noise, and cannot achieve good dynamic control and locking effects.

[0009] The second solution is to apply a perturbation signal related to the bias voltage and detect the amplitude of the signal component with the same frequency as the applied perturbation signal in the output signal to maintain the bias operating point of the silicon-based optical modulator, as described in patent CN114137744A. This solution needs to introduce a perturbation signal first, and the size of the perturbation signal directly affects the jitter degree of the signal. A larger perturbation signal will make the modulation signal unable to be analyzed, resulting in uncorrectable bit errors and affecting the communication status of the link. At the same time, the method is relatively complex and requires linear fitting, integration, etc. The calculation accuracy is related to the perturbation signal and is not convenient for actual use.

[0010] The third solution is to establish a non-linear function relationship between the Fourier series ratio and the bias operating point, compare the real-time value with the current expected value, and perform feedback control to make the modulator operate at the expected bias operating point, as described in Patent CN117040643A. This solution uses the Fourier transform region to establish a non-linear function relationship between the Fourier series ratio and the bias operating point, obtains the current expected value through the expected bias operating point and the Fourier series ratio, and adjusts the bias voltage until the Fourier series ratio is equal to the expected value. However, the Fourier transform has a certain delay in processing real-time signals. Since the entire signal needs to be processed, it takes a certain amount of time to complete the calculation, and this delay may cause certain problems in applications with high real-time requirements; it will process the noise components together, which may have a greater impact on the spectrum analysis results. Summary of the Invention

[0011] The present invention proposes a control system for locking the bias operating point of a silicon-based chip with an MZM structure, which solves the problems of poor adjustment effect and difficult adjustment in the prior art.

[0012] The present invention also proposes a control method for a control system for locking the bias operating point of a silicon-based chip with an MZM structure, which solves the problems of complex adjustment methods in the prior art.

[0013] The technical solution of the present invention is realized as follows: A control system for locking the bias operating point of a silicon-based chip with an MZM structure includes a silicon-based chip, two sampling circuits, an MCU control unit, a multi-channel operational amplifier, and a host computer. The silicon-based chip includes an MZM modulator, and the MZM modulator includes modulation arm A, modulation arm B, a heater, an A-arm photodiode, and a B-arm photodiode. The heater is arranged on modulation arm A. Modulation arm A is electrically connected to the A-arm photodiode and a sampling circuit in sequence. Modulation arm B is electrically connected to the B-arm photodiode and another sampling circuit in sequence. The two sampling circuits are respectively electrically connected to the MCU control unit. The MCU control unit is electrically connected to the multi-channel operational amplifier. The multi-channel operational amplifier is respectively electrically connected to modulation arm A and modulation arm B. The MCU control unit is electrically connected to the host computer.

[0014] Further, the silicon-based chip includes at least two MZM modulators, and the MZM modulators are electrically connected in parallel. One MZM modulator is electrically connected to the corresponding two sampling circuits.

[0015] Further, it further includes a digital signal processing chip or a driver chip integrated with a linear equalization function. The silicon-based chip is provided with multiple groups of high-speed radio frequency signal electrical interfaces for electrically connecting to the digital signal processing chip or the driver chip integrated with the linear equalization function. The silicon-based chip is electrically connected to an external power supply.

[0016] Furthermore, the control system further includes a laser, and the MZM modulator further includes a beam splitter and a combiner. The beam splitter is disposed between the two modulation arms and the laser, and the combiner is disposed at one end of the two modulation arms away from the beam splitter.

[0017] A control method for a control system for locking the bias operating point of a silicon-based chip with an MZM structure includes the following steps: Step 1, the MCU control unit adjusts the drive voltage and current over the full range. Each sampling circuit collects the voltage and current signals of a corresponding modulation arm by monitoring a corresponding photodiode, and transmits the collected voltage and current signals to the MCU control unit. The MCU control unit converts the received analog voltage and current signals into digital signals and transmits them to the host computer, and the host computer generates two drive current-monitoring voltage working curves. Step 2, find multiple intersection points within the full cycle range of the set drive current. Select the drive current-monitoring voltage working curve of the modulation arm with a heater in the MZM modulator as a reference, and use its rising edge as the selection criterion. Select the intersection point corresponding to the first rising edge, obtain the drive current corresponding to the intersection point, and use the drive current corresponding to the intersection point of the first rising edge as a judgment. If the drive current is less than the set standard value, then select the intersection point corresponding to the second rising edge, and obtain the drive current corresponding to the intersection point of the second rising edge as the debugging current; if the drive current corresponding to the intersection point of the first rising edge is not less than the set standard value, then still select the drive current corresponding to the intersection point of the first rising edge as the debugging current. Step 3, after selecting the best intersection point, use the 3 dB drop point of the optical intensity peak corresponding to the best intersection point as the reference bias operating point, and use the ratio Ratio of the drive voltages of the two modulation arms corresponding to this operating point as the standard for dynamically adjusting the operating point. Step 4, when it is detected that the voltage ratio value corresponding to the bias operating point of the MZM modulator is not equal to the Ratio value, dynamically adjust the drive voltage or current so that the ratio of the drive voltages of the two arms of the corresponding bias operating point is consistent with the two-voltage ratio standard obtained from the reference bias operating point in Step 3. Taking Ratio as the central standard, if the voltage ratio value corresponding to the bias operating point > Ratio value, then adjust the modulation voltage or current on the modulation arm with a heater downward so that the adjusted voltage ratio value approaches the Ratio value; conversely, if the voltage ratio value corresponding to the bias operating point < Ratio value, then adjust the modulation voltage or current on the modulation arm with a heater upward so that the adjusted voltage ratio value approaches the Ratio value.

[0018] Furthermore, the ratio Ratio of the two voltages of the reference bias operating point is the proportional coefficient of the two voltages. Use V W / H to represent the modulation voltage on the modulation arm with a heater in the MZM modulator. Use VW / O represents the modulation voltage on the modulation arm without a heater in the MZM modulator, then Ratio = V W / H / V W / O .

[0019] Furthermore, a ±3% adjustment range is set near Ratio, and this range is used as the range for dynamically adjusting the operating point. That is, the adjusted voltage ratio value is not less than 97%Ratio and not greater than 103%Ratio 。

[0020] Furthermore, when adjusting the modulation voltage or current on the modulation arm with a heater downwards, the drive voltage or current is reduced in small steps, and when adjusting the modulation voltage or current on the modulation arm with a heater upwards, the drive voltage / current is increased in small steps.

[0021] The beneficial effects of the present invention are as follows: The control system and control method for locking the bias operating point of the silicon-based chip with the MZM structure of the present invention can automatically find the optimal operating point under different working environments through innovative method design and control logic, realizing dynamic stability of the bias point with high precision, high efficiency, and low latency, providing core technical support for high-speed silicon optical modules. The control system and control method for locking the bias operating point of the silicon-based chip with the MZM structure of the present invention build a relatively simple control system, reducing peripheral costs, reducing power consumption, occupying a small space in high-speed optical modules, facilitating the layout of other electrical chips, and achieving high circuit reliability; by designing a new and precise control method, it is easy to implement, has high precision, does not rely on other external devices, has a fast response speed, is convenient to operate, and has high stability, and is used for dynamically locking the bias operating point of the MZM modulator, real-time monitoring the drift amount of the operating point and feedback-adjusting the bias voltage to ensure that the silicon-based chip with the MZM structure always operates in the optimal linear region.

[0022] 1) Build a relatively simple control system, reduce peripheral costs, reduce power consumption, occupy a small space in high-speed optical modules, facilitate the layout of other electrical chips, achieve high circuit reliability, and facilitate product implementation; 2) Design a new and precise control method, cooperate with the peripheral control system, is easy to implement, does not rely on other external devices, is convenient to operate, and has high stability; 3) Can be used in cooperation with different silicon-based chips. Just adjust according to the working voltage or current of the corresponding silicon-based chip, select a suitable multi-channel operational amplifier, and scale the drive voltage or current of the control system to different degrees, which can achieve high control precision and make it at the optimal operating point with high precision.

[0023] 4) It can monitor the working conditions in real time, with fast response speed and high efficiency. It can adjust the driving voltage or current according to the real-time working conditions, has strong anti-interference ability, and realizes the locking of the optimal working point. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 It is the system schematic diagram of the control system for locking the bias working point of the silicon-based chip with an MZM structure of the present invention; Figure 2 It is the structural schematic diagram of the MZM modulator; Figure 3 It is the flowchart of the control method for locking the bias working point of the silicon-based chip with an MZM structure; Figure 4 It is the working curve graph of the driving current - monitoring voltage of the two arms obtained by adjusting the driving current in the full range. The abscissa represents the digital sampling value of the driving current; the ordinate represents the digital sampling value of the monitoring voltage; In the drawings: 1 - Modulation arm A; 2 - Modulation arm B; 3 - Heater; 4 - Photodiode of arm A; 5 - Photodiode of arm B. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] The present invention provides a control system and a control method for locking the bias working point of a silicon-based chip with an MZM structure, which are used to dynamically lock the MZM bias working point, monitor the working point drift amount in real time and feedback to adjust the bias voltage, so as to ensure that the silicon-based chip with an MZM structure always works in the optimal linear region.

[0028] The control system for locking the bias working point of the silicon-based chip with an MZM structure is as Figure 1 shown: The forward circuit includes a Digital Signal Processing (DSP) chip or a Driver chip integrated with CTLE (Continuous Time Linear Equalizer) function, both of which are used to compensate the high-speed signals coming forward to a certain extent and electrically connect the compensated high-speed radio frequency signals to the silicon-based chip.

[0029] As Figure 2 shown, the beam splitter on the MZM modulator couples the light emitted by the laser, which is responsible for the input of the laser power from the laser; the combiner on the MZM modulator couples and emits the output light, and the output optical power is output through the fiber array.

[0030] Each MZM modulator is independent of each other and is driven by its respective drive current electrical interface. Each MZM modulator has two parallel arms. The input optical signal is split into two beams of light with exactly the same amplitude and phase after passing through the beam splitter, and then transmitted along the upper and lower branches of the optical waveguide. By the difference in the modulation voltages applied to the two arms, the refractive index of the optical waveguide is changed, so that the phases of the two beams of light in the two parallel arms are changed, and finally the two beams of light are combined into a beam of light different from the original input optical signal at the combiner.

[0031] The multiple groups of high-speed radio frequency signal electrical interfaces of the silicon-based chip receive the high-speed radio frequency signals compensated by the front end. The power supply interface of the silicon-based chip is electrically connected to the peripheral power supply, which is responsible for supplying power to the silicon-based chip. The monitoring photodiode interface of the MZM modulator is electrically connected to the sampling circuit and then to the MCU control unit to monitor the sampling in real time to determine whether it is at the bias operating point. The multi-channel operational amplifiers are respectively electrically connected to modulation arm A and modulation arm B, and are responsible for adjusting the drive voltage or current of the MZM modulator.

[0032] A sampling circuit collects the voltage and current signals on one drive arm of the MZM modulator for feedback and transmits them to the peripheral MCU control unit; the peripheral MCU control unit not only receives the feedback signals of each MZM modulator from the sampling circuit, but also provides multiple bias voltages for the silicon-based chip. By real-time feedback of the working point drift amount, multiple bias voltages are adjusted by using the subsequent bias working point locking control method, so that the silicon-based chip is at the optimal bias point under different working conditions, realizing the dynamic stability of the bias point.

[0033] The multi-channel operational amplifier can amplify the drive voltage or current signals output by the peripheral MCU control unit to meet the working range of different bias working points of the silicon-based chip.

[0034] The control method for locking the bias working point of the silicon-based chip with MZM structure, the control flow is as Figure 3 shown, and the specific steps are as follows: 1) The MCU control unit adjusts the driving voltage and current over the full range. Each sampling circuit collects the voltage and current signals of a corresponding modulation arm by monitoring a corresponding photodiode, generates a driving voltage or current as the modulation signal input for the two driving arms on the MZM modulator through the MCU control unit, and changes the refractive index and phase change in the two optical path branches through the magnitude and phase change of the driving voltage or current within the modulation range, realizing the optical intensity modulation on the two modulation arms of the MZM modulator. The sampling circuits on the peripheral circuit form a monitoring photodiode detection circuit, transmit the collected voltage and current signals to the peripheral MCU control unit, the MCU control unit converts the received analog signals of voltage and current into digital signals and transmits them to the host computer, and the host computer generates two driving current - monitoring voltage working curves to determine the bias operating point of the modulator in the current state and obtain the magnitude of the driving current at the bias operating point. As shown in Figure 4 shown, the conversion relationship between the monitoring voltage V mon and the digital sampling value of the monitoring voltage is as follows:

[0035] Among them, the unit of the monitoring voltage V mon is consistent with the unit of the total voltage corresponding to the full range of the digital sampling of the monitoring voltage.

[0036] The conversion relationship between the driving current I mon and the digital sampling value of the driving current on the abscissa is as follows:

[0037] Among them, the unit of the driving current I mon is consistent with the unit of the total current corresponding to the full range of the digital sampling of the driving current.

[0038] 2) After obtaining the driving current - monitoring voltage working curve, find multiple positive intersections within the full cycle range of the set driving current. Select the driving current - monitoring voltage working curve of the modulation arm with a heater in the MZM modulator as a reference, use its rising edge as the selection criterion, select the positive intersection corresponding to its first rising edge, obtain the driving current corresponding to its positive intersection, and use its driving current as a judgment. If its driving current is less than the set standard value, then select the positive intersection corresponding to its second rising edge, and obtain the driving current corresponding to the second rising edge positive intersection as the debugging current; if the driving current of the positive intersection corresponding to the first rising edge is not less than the set standard value, then still select the driving current corresponding to the positive intersection of its first rising edge as the debugging current.

[0039] 3) Determine the bias operating point, and use the voltage ratio value corresponding to this bias operating point as the standard for the dynamic locking operating point. After selecting the optimal intersection point, use the point where the optical intensity peak corresponding to the optimal intersection point drops by 3 dB (optical power gain or attenuation value) as the reference bias operating point, and use the ratio of the driving voltages of the two modulation arms corresponding to this operating point as the standard for dynamically adjusting the operating point.

[0040]

[0041] Among them, V W / H is the modulation voltage on the modulation arm with a heater in the MZM modulator, and V W / O is the modulation voltage on the modulation arm without a heater in the MZM modulator, and Ratio is the proportional coefficient of the two voltages.

[0042] 4) In different environments, due to the influence of the material's own characteristics, temperature, device aging and other factors of the MZM modulator, the initial bias point will slowly drift over time. When it is detected that the voltage ratio value corresponding to the bias operating point of the MZM modulator in this state is not equal to the Ratio value, dynamically adjust the driving voltage or current so that the ratio of the driving voltages of the two arms of the corresponding bias operating point is consistent with the ratio standard obtained above.

[0043] Taking Ratio as the central standard, set an adjustment range of ±3% near Ratio, and use this range as the range for dynamically adjusting the operating point. If the voltage ratio value at the bias operating point > Ratio value, then adjust down the modulation voltage or current on the modulation arm with a heater, that is, slightly step down the driving voltage or current to make the adjusted voltage ratio value as close as possible to the Ratio value (that is, the adjusted voltage ratio value is not less than 97%Ratio and not greater than 103%Ratio); conversely, if the voltage ratio value at the bias operating point < Ratio value, then adjust up the modulation voltage or current on the modulation arm with a heater, that is, slightly step up the driving voltage / current to make the adjusted voltage ratio value as close as possible to the Ratio value (that is, the adjusted voltage ratio value is not less than 97%Ratio and not greater than 103%Ratio). Thus, dynamically adjust the bias operating point of the MZM modulator to ensure that the MZM modulator operates in the best state and guarantee the product performance.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control system for locking the bias operating point of a silicon-based chip with an MZM structure, characterized in that: It includes a silicon-based chip, two sampling circuits, an MCU control unit, a multi-channel operational amplifier, and a host computer. The silicon-based chip includes an MZM modulator. The MZM modulator includes a modulation arm A, a modulation arm B, a heater, a photodiode of arm A, and a photodiode of arm B. The heater is arranged on the modulation arm A. The modulation arm A is electrically connected to the photodiode of arm A and a sampling circuit in sequence. The modulation arm B is electrically connected to the photodiode of arm B and another sampling circuit in sequence. The two sampling circuits are respectively electrically connected to the MCU control unit. The MCU control unit is electrically connected to the multi-channel operational amplifier. The multi-channel operational amplifier is respectively electrically connected to the modulation arm A and the modulation arm B. The MCU control unit is electrically connected to the host computer.

2. The control system for locking the bias operating point of the silicon-based chip with the MZM structure according to claim 1, characterized in that: The silicon-based chip includes at least two MZM modulators, which are electrically connected in parallel. One MZM modulator is electrically connected to two corresponding sampling circuits.

3. The control system for locking the bias operating point of the silicon-based chip with the MZM structure according to claim 1, characterized in that: It further includes a digital signal processing chip or a driver chip integrated with a linear equalization function. There are multiple groups of high-speed radio frequency signal electrical interfaces on the silicon-based chip for electrically connecting with the digital signal processing chip or the driver chip integrated with the linear equalization function. The silicon-based chip is electrically connected to an external power supply.

4. The control system for locking the bias operating point of the silicon-based chip with the MZM structure according to claim 1, characterized in that: The control system further includes a laser. The MZM modulator further includes a beam splitter and a combiner. The beam splitter is arranged between the two modulation arms and the laser. The combiner is arranged at one end of the two modulation arms away from the beam splitter.

5. A control method for a control system of locking the bias operating point of a silicon-based chip with an MZM structure as described in any one of claims 1-4, characterized in that It includes the following steps: Step 1: The MCU control unit adjusts the driving voltage and current within the full range. Each sampling circuit collects the voltage and current signals of a corresponding modulation arm by monitoring a corresponding photodiode, and transmits the collected voltage and current signals to the MCU control unit. The MCU control unit converts the received analog voltage and current signals into digital signals and transmits them to the host computer. The host computer generates two driving current-monitoring voltage working curves. Step 2: Find multiple intersection points within the full cycle of the set driving current. Select the driving current-monitoring voltage working curve of the modulation arm with a heater in the MZM modulator as a reference, and use its rising edge as the selection criterion. Select the intersection point corresponding to its first rising edge, and obtain the driving current corresponding to the intersection point. Use the driving current of the intersection point corresponding to the first rising edge as a judgment. If the driving current is less than the set standard value, then select the intersection point corresponding to its second rising edge, and obtain the driving current corresponding to the second rising edge intersection point as the debugging current. If the driving current of the intersection point corresponding to the first rising edge is not less than the set standard value, still select the driving current of the intersection point corresponding to the first rising edge as the debugging current. Step 3: After selecting the best intersection point, use the 3 dB drop point of the light intensity peak corresponding to the best intersection point as the reference bias working point, and use the ratio Ratio of the driving voltages of the two modulation arms corresponding to this working point as the standard for dynamically adjusting the working point. Step 4: When it is detected that the voltage ratio value corresponding to the bias operating point of the MZM modulator is not equal to the Ratio value, dynamically adjust the driving voltage or current so that the ratio of the driving voltages of the two arms of the corresponding bias operating point is the same as the standard ratio of the two voltages obtained from the reference bias operating point in Step 3. Taking Ratio as the central standard, if the voltage ratio value corresponding to the bias operating point > Ratio value, then adjust downward the modulation voltage or current on the modulation arm with a heater so that the adjusted voltage ratio value approaches the Ratio value; conversely, if the voltage ratio value corresponding to the bias operating point < Ratio value, then adjust upward the modulation voltage or current on the modulation arm with a heater so that the adjusted voltage ratio value approaches the Ratio value.

6. The control method of the control system for locking the bias operating point of the silicon-based chip with the MZM structure as claimed in claim 5, characterized in that: The ratio Ratio of the two voltages at the reference bias operating point is the proportionality coefficient of the two voltages, denoted by V W / H represents the modulation voltage on the modulated arm with a heater in the MZM modulator, denoted by V W / O represents the modulation voltage on the modulated arm without a heater in the MZM modulator, then Ratio = V W / H / V W / O .

7. The control method of the control system for locking the bias operating point of the silicon-based chip of the MZM structure according to claim 5, characterized in that: Set an adjustment range of ±3% near Ratio and use this range as the range for dynamically adjusting the operating point.

8. The control method of the control system for locking the bias operating point of the silicon-based chip of the MZM structure according to claim 5, characterized in that: When adjusting downward the modulation voltage or current on the modulation arm with a heater, reduce the driving voltage or current in small steps; when adjusting upward the modulation voltage or current on the modulation arm with a heater, increase the driving voltage or current in small steps.

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