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

Abstract

This invention proposes a control system for bias-locked operating points in a silicon-based chip with an MZM structure. The control system comprises 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, which comprises modulation arms A and B, a heater, and photodiodes for arm A and arm B. A sampling circuit collects voltage and current signals from a driving arm of the MZM modulator, transmits them to a peripheral MCU control unit, and then uploads them to the host computer. The MCU control unit regulates the voltage or current of modulation arm A via the multi-channel operational amplifier. The invention also proposes a control method for bias-locked operating points in a silicon-based chip with an MZM structure. The control system occupies a small space in a high-speed optical module, facilitating the layout of other electronic chips and achieving high circuit reliability. This system utilizes a novel and precise control method.

Description

Technical Field

[0001] The present invention relates to the technical field of optical modulators, and in particular 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 communications, data centers, and cloud computing technologies, demands for bandwidth, power consumption, and transmission speeds in optical communication systems are skyrocketing. As core components of optical networks, high-speed optical modules must meet speed requirements of 400G / 800G, and even 1.6T, while also maintaining low power consumption, compact size, and high reliability. Silicon photonics, with its CMOS process compatibility, high integration, and low cost, has become a core technology for high-speed optical modules.

[0003] The Mach-Zehnder modulator (MZM) is a key component for implementing electro-optical modulation in silicon chips. It converts electrical signals into optical signals by changing the refractive index of an optical waveguide using an electrical signal. The performance of the MZM directly determines key metrics of high-speed optical modules, such as modulation efficiency, linearity, and bit error rate (BER). To achieve high-quality signal modulation, the MZM modulator must operate at a specific bias point (quadrature bias point) to maximize the modulator's linear region and extinction ratio (ER).

[0004] However, the bias operating point of an MZM modulator is susceptible to drift due to the following factors: 1) temperature fluctuations. The refractive index of silicon material is thermally sensitive, and changes in ambient temperature cause the waveguide's refractive index to change; 2) device aging. Over long-term operation, waveguide material properties (such as carrier concentration and stress distribution) gradually degrade; and 3) drive voltage drift. The electrical parameters of the drive circuit (such as bias voltage and impedance matching) drift over time. If the bias point deviates from the optimal position, it will lead to signal distortion, a decrease in extinction ratio, and increased nonlinear effects, seriously degrading 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 challenge in the design of high-speed silicon photonic modules.

[0005] Silicon-based Mach-Zehnder modulators (MZMs) utilize the plasmon dispersion effect of silicon materials. By applying a reverse bias voltage to the PN junctions on either side of a waveguide, the carrier concentration (electrons and holes) is altered, thereby regulating the waveguide's refractive index. An MZM typically consists of two symmetrical Y-branch waveguides. The input optical signal is split into two paths, which are then recoupled after phase modulation. The output light intensity is determined by the phase difference between the two arms:

[0006]

[0007] in, is the phase difference between the two arms, which is linearly related to the driving voltage V.

[0008] The bias operating point of the MZM is usually selected at the quadrature point of the transmission curve (i.e. At this point, the modulator achieves maximum linearity and extinction ratio. If the bias point drifts into nonlinear regions (such as peaks or valleys) due to factors like temperature and aging, signal distortion, eye closure, and increased bit errors can result. Therefore, the technology for dynamically locking the MZM bias operating point is a key parameter that determines its modulation performance.

[0009] Currently, there are several main approaches for locking the bias operating point of silicon-based chips with MZM structures. The first approach uses a programmable system-on-chip (PSOC) and proportional-integral-differential (PID) control to achieve the optimal operating point of the electro-optical modulator, as described in patent CN105302019A. This peripheral control device, consisting of a photodetector, controller, voltage amplifier circuit, adder circuit, error comparator, and second-order low-pass filter circuit, requires closed-loop control. This occupies a large area in high-speed optical modules and has a complex structure. Furthermore, the PID control method requires high parameter adjustment requirements, and linearization is required for this nonlinear system to improve control accuracy. This solution achieves a bias voltage tracking accuracy of only 100mV and is also sensitive to external interference noise, failing to achieve good dynamic control and locking effects.

[0010] The second approach, as described in patent CN114137744A, involves applying a perturbation signal related to the bias voltage and detecting the amplitude of a 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. This approach requires the introduction of a perturbation signal, the magnitude of which directly affects the degree of signal jitter. A large perturbation signal can make the modulated signal unresolvable, resulting in uncorrectable errors and affecting the communication status of the link. Furthermore, the method is complex, requiring linear fitting and integration. The calculation accuracy is dependent on the perturbation signal, making it inconvenient for practical use.

[0011] A third approach involves establishing a nonlinear functional relationship between the Fourier series ratio and the bias operating point, comparing the real-time value with the current expected value, and performing feedback control to maintain the modulator at the desired bias operating point, as described in patent CN117040643A. This approach uses the Fourier transform region to establish a nonlinear functional relationship between the Fourier series ratio and the bias operating point. The current expected value is obtained by comparing the expected bias operating point with the Fourier series ratio, and the bias voltage is adjusted until the Fourier series ratio equals the expected value. However, the Fourier transform has a certain delay when processing real-time signals. Since the entire signal needs to be processed, the calculation takes a certain amount of time to complete. This delay can cause certain problems in applications with high real-time requirements. It also processes noise components together, which may have a significant impact on the spectrum analysis results. Summary of the Invention

[0012] 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 bias operating point adjustment effect and difficulty in adjustment in the prior art.

[0013] The present invention also proposes a control method for a control system of a silicon-based chip bias operating point locking of an MZM structure, which solves the problems of complex adjustment methods in the prior art.

[0014] The technical solution of the present invention is achieved as follows: a control system for bias operating point locking of a silicon-based chip with an MZM structure, comprising a silicon-based chip, two sampling circuits, an MCU control unit, a multi-channel operational amplifier, and a host computer, wherein 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, the heater being arranged on the modulation arm A, the modulation arm A being electrically connected to the A-arm photodiode and a sampling circuit in sequence, the modulation arm B being electrically connected to the B-arm photodiode and another sampling circuit in sequence, the two sampling circuits being electrically connected to the MCU control unit respectively, the MCU control unit being electrically connected to the multi-channel operational amplifier, the multi-channel operational amplifier being electrically connected to the modulation arm A and the modulation arm B respectively, and the MCU control unit being electrically connected to the host computer.

[0015] Furthermore, the silicon-based chip includes at least two MZM modulators, the MZM modulators are electrically connected in parallel, and one MZM modulator is electrically connected to two corresponding sampling circuits.

[0016] Furthermore, it also includes a digital signal processing chip or a driver chip with integrated linear equalization function. The silicon-based chip is provided with multiple sets of high-speed RF signal electrical interfaces for electrically connecting to the digital signal processing chip or the driver chip with integrated linear equalization function, and the silicon-based chip is electrically connected to an external power supply.

[0017] Further, 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.

[0018] A control method for a control system for locking a bias operating point of a silicon-based chip with an MZM structure includes the following steps: Step 1, the MCU control unit adjusts the driving voltage and current in a 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 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.

[0019] Step 2, find multiple intersection points 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, and use its rising edge as the selection criterion. Select the intersection point corresponding to the first rising edge, obtain the driving current corresponding to the intersection point, and use the driving current corresponding to the intersection point of 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 the second rising edge, and obtain the driving current corresponding to the second rising edge intersection point as the debugging current; if the driving current corresponding to the intersection point of the first rising edge is not less than the set standard value, still select the driving current corresponding to the intersection point of the first rising edge as the debugging current.

[0020] 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 driving voltages of the two modulation arms corresponding to this operating point as the standard for dynamically adjusting the operating point.

[0021] 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 to make the ratio of the driving voltages of the two arms of the corresponding bias operating point 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 to make the adjusted voltage ratio value close to 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 to make the adjusted voltage ratio value close to the Ratio value.

[0022] Further, the ratio Ratio of the two voltages of the reference bias operating point is the proportional coefficient of the two voltages, using VW / H The modulation voltage on the modulation arm with heater in the MZM modulator is represented by V W / O represents the modulation voltage on the modulation arm without heater in the MZM modulator, then Ratio = V W / H / V W / O .

[0023] Furthermore, a ±3% adjustment range is set around the Ratio, and this range is used as the range of the dynamic adjustment working point. That is, the voltage ratio value after adjustment is not less than 97% of the Ratio and not greater than 103% of the Ratio 。

[0024] Furthermore, the modulation voltage or current on the modulation arm with the heater is adjusted downward by reducing the driving voltage or current in small steps, and the modulation voltage or current on the modulation arm with the heater is adjusted upward by increasing the driving voltage / current in small steps.

[0025] 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 of the MZM structure of the present invention, through innovative method design and control logic, can automatically find the optimal operating point under different working environments, achieve high-precision, high-efficiency, low-latency bias point dynamic stability, and provide core technical support for high-speed silicon photonic modules. The control system and control method for locking the bias operating point of the silicon-based chip of the MZM structure of the present invention build a relatively simple control system, reduce peripheral costs and power consumption, occupy a small space in the high-speed optical module, facilitate the layout of other electrical chips, and achieve higher circuit reliability; by designing a new and precise control method, it is easy to implement, has high precision, does not need to rely on other external devices, has a fast response speed, is easy to operate, and has high stability. It is used to dynamically lock the bias operating point of the MZM modulator, monitor the operating point drift in real time, and feedback-adjust the bias voltage to ensure that the silicon-based chip of the MZM structure always operates in the optimal linear region.

[0026] 1) Build a simpler control system, reduce peripheral costs and power consumption, take up less space in high-speed optical modules, facilitate the layout of other electronic chips, achieve higher circuit reliability, and facilitate product implementation;

[0027] 2) Design a new and precise control method, which is easy to implement in conjunction with the peripheral control system, does not rely on other external equipment, is easy to operate and has high stability;

[0028] 3) It can be used with different silicon-based chips. It only needs to be adjusted according to the working voltage or current of the corresponding silicon-based chip, and the appropriate multi-channel operational amplifier is selected to scale the driving voltage or current of the control system to different degrees. This can achieve higher control accuracy and make it at the optimal working point with high precision.

[0029] 4) It can monitor the working conditions in real time, with fast response speed and high efficiency, 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

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a system principle diagram of a control system for bias operating point locking of a silicon-based chip with an MZM structure according to the present invention;

[0032] Figure 2 This is the structural principle diagram of the MZM modulator;

[0033] Figure 3 A flow chart of a control method for locking the bias operating point of a silicon-based chip with an MZM structure;

[0034] Figure 4 The working curve of the driving current-monitoring voltage of the two arms obtained by adjusting the driving current in the full range is shown in the figure. The horizontal axis represents the digital sampling value of the driving current; the vertical axis represents the digital sampling value of the monitoring voltage.

[0035] In the accompanying drawings: 1-modulation arm A; 2-modulation arm B; 3-heater; 4-A arm photodiode; 5-B arm photodiode. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] The patent of this invention provides a control system and control method for locking the bias operating point of a silicon-based chip with an MZM structure, which is used to dynamically lock the MZM bias operating point, monitor the operating point drift in real time, and feedback-adjust the bias voltage to ensure that the silicon-based chip with an MZM structure always operates in the optimal linear region.

[0038] The control system of MZM structure silicon chip bias operating point locking, such as Figure 1 As shown:

[0039] The forward circuit includes a digital signal processing (DSP) chip or a driver chip with integrated CTLE (linear equalization) function, both of which are used to compensate the high-speed signal transmitted from the forward direction to a certain extent and electrically connect the compensated high-speed RF signal to the silicon-based chip.

[0040] like Figure 2 As shown, the beam splitter on the MZM modulator couples the light emitted by the laser and is responsible for the laser power input from the laser; the beam combiner on the MZM modulator couples the emitted output light and outputs the optical power through the optical fiber array.

[0041] Each MZM modulator is independent and driven by its own current-generating electrical interface. Each MZM modulator has two parallel arms. The input optical signal passes through a beam splitter, splitting it into two beams of identical amplitude and phase. These beams are then transmitted along the upper and lower branches of the optical waveguide. The difference in modulation voltage applied to the two arms changes the refractive index of the optical waveguide, shifting the phase of the two beams in the parallel arms. Finally, the beams are combined in a beam combiner to form a beam different from the original input signal.

[0042] The multiple sets of high-speed RF signal electrical interfaces of the silicon-based chip receive the high-speed RF signals after front-end compensation. The power supply interface of the silicon-based chip is electrically connected to the external power supply and is responsible for powering 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 for real-time monitoring and sampling to determine whether it is at the bias operating point. The multi-channel operational amplifier is electrically connected to the modulation arm A and the modulation arm B respectively, and is responsible for adjusting the driving voltage or current of the MZM modulator.

[0043] A sampling circuit collects the voltage and current signals on a driving 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 signal 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 operating point drift, the subsequent bias operating point locking control method is used to adjust the multiple bias voltages, so that the silicon-based chip is at the optimal bias point under different operating conditions, achieving dynamic stability of the bias point.

[0044] The multi-channel operational amplifier can amplify the driving voltage or current signal output by the peripheral MCU control unit to meet the working range of different silicon-based chip bias operating points.

[0045] The control method of bias operating point locking of silicon-based chip with MZM structure, the control process is as follows Figure 3 The specific steps are as follows:

[0046] 1) The MCU control unit adjusts the driving voltage and current over the entire range. Each sampling circuit collects the voltage and current signals of the corresponding modulation arm by monitoring a corresponding photodiode. The MCU control unit generates a driving voltage or current as the modulation signal input for the two driving arms on the MZM modulator. By changing the magnitude and phase of the driving voltage or current within the modulation range, the refractive index and phase changes in the two optical path branches are changed, thereby realizing light intensity modulation on the two modulation arms of the MZM modulator. The sampling circuit on the peripheral circuit constitutes a monitoring photodiode detection circuit, and transmits 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. 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 driving current magnitude under the bias operating point, such as Figure 4 As shown, the monitoring voltage V mon The conversion relationship with the monitoring voltage digital sampling value is as follows:

[0047]

[0048] Among them, the monitoring voltage V mon The unit is consistent with the unit of the total voltage corresponding to the total range of digital sampling.

[0049] Drive current I mon The conversion relationship with the digital sampling value of the horizontal axis drive current is as follows:

[0050]

[0051] Among them, the driving current I mon The unit is consistent with the unit of the total current corresponding to the total range of the driving current digital sampling.

[0052] 2) After obtaining the driving current-monitoring voltage working curve, find multiple orthogonal points within the set driving current full cycle range, 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 standard, select the orthogonal point corresponding to its first rising edge, obtain the driving current corresponding to its orthogonal point, and use its driving current as a judgment. If its driving current is less than the set standard value, select the orthogonal point corresponding to its second rising edge, and obtain the driving current corresponding to the orthogonal point of the second rising edge as the debugging current; if the driving current of the orthogonal point corresponding to the first rising edge is not less than the set standard value, then the driving current corresponding to the orthogonal point of the first rising edge is still selected as the debugging current.

[0053] 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.

[0054]

[0055] 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 proportionality coefficient of the two voltages.

[0056] 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.

[0057] Taking Ratio as the central standard, set a ±3% adjustment range near Ratio and use this range as the range for dynamically adjusting the operating point. If the voltage ratio value under the bias operating point > Ratio value, then adjust downward the modulation voltage or current on the modulation arm with a heater, that is, gradually reduce the driving voltage or current in small steps so that the adjusted voltage ratio value is 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 under the bias operating point < Ratio value, then adjust upward the modulation voltage or current on the modulation arm with a heater, that is, gradually increase the driving voltage / current in small steps so that the adjusted voltage ratio value is 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.

[0058] 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 principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control system for bias-locked operating point of a silicon-based chip with an MZM structure, characterized by: The invention comprises a silicon-based chip, two sampling circuits, an MCU control unit, a multi-channel operational amplifier and a host computer, wherein 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, the heater is arranged on the modulation arm A, the modulation arm A is electrically connected to the A-arm photodiode and a sampling circuit in sequence, the modulation arm B is electrically connected to the B-arm photodiode and another sampling circuit in sequence, the two sampling circuits are electrically connected to the MCU control unit respectively, the MCU control unit is electrically connected to the multi-channel The operational amplifier is electrically connected, the multi-channel operational amplifier is electrically connected to the modulation arm A and the modulation arm B respectively, the MCU control unit is electrically connected to the host computer, the control system also includes a laser, the MZM modulator also includes a beam splitter and a beam combiner, the beam splitter is arranged between the two modulation arms and the laser, and the beam combiner is arranged at one end of the two modulation arms away from the beam splitter. The beam splitter on the MZM modulator couples the light emitted by the laser and is responsible for the laser power input from the laser; the beam combiner on the MZM modulator couples the emitted output light and outputs the optical power through the optical fiber array.

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

3. The control system for bias-locked silicon chip bias operating point of the MZM structure according to claim 1, characterized in that: It also includes a digital signal processing chip or a driver chip with integrated linear equalization function. The silicon-based chip is provided with multiple sets of high-speed RF signal electrical interfaces for electrically connecting to the digital signal processing chip or the driver chip with integrated linear equalization function, and the silicon-based chip is electrically connected to a peripheral power supply.

4. A control method for a control system for a silicon-based chip bias operating point locking of an MZM structure according to any one of claims 1 to 3, characterized in that The following steps are involved: Step 1: The MCU control unit adjusts the driving voltage and current over the entire 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 signals of voltage and current 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 orthogonal points within the set full cycle range of the 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 standard, select the orthogonal point corresponding to its first rising edge, obtain the driving current corresponding to its orthogonal point, and use the driving current of the orthogonal point corresponding to the first rising edge as a judgment. If its driving current is less than the set standard value, select the orthogonal point corresponding to its second rising edge, and obtain the driving current corresponding to the orthogonal point of the second rising edge as the debugging current; if the driving current of the orthogonal point corresponding to the first rising edge is not less than the set standard value, then the driving current corresponding to the orthogonal point of the first rising edge is still selected as the debugging current; Step 3: After selecting the optimal orthogonality point, use the 3 dB drop point of the optical intensity peak corresponding to the optimal orthogonality point as the reference bias operating point, and use the ratio of the driving voltages of the two modulation arms corresponding to this operating point, Ratio, 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 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 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 down 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 up the modulation voltage or current on the modulation arm with a heater so that the adjusted voltage ratio value approaches the Ratio value.

5. The control method of the control system for bias operating point locking of a silicon-based chip with an MZM structure as claimed in claim 4, characterized in that: The ratio of the two voltages at the reference bias operating point is the proportional coefficient of the two voltages, and V W / H The modulation voltage on the modulation arm with heater in the MZM modulator is represented by V W / O represents the modulation voltage on the modulation arm without heater in the MZM modulator, then Ratio = V W / H / V W / O .

6. The control method for a control system for bias-locked operation point of a silicon-based chip with an MZM structure according to claim 4, characterized in that: Set an adjustment range of ±3% near Ratio, and use this range as the range for dynamically adjusting the operating point.

7. The control method of a control system for bias-locked operation point of a silicon-based chip with an MZM structure according to claim 4, characterized in that: When adjusting down the modulation voltage or current on the modulation arm with a heater, reduce the driving voltage or current in small steps, and when adjusting up 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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