Multi-segment MZM closed-loop control system and method based on dynamic electric field regulation and control

Abstract

The invention discloses a multi-segment MZM closed-loop control system and method based on dynamic electric field regulation and control, and relates to the technical field of optical signal modulation, and the method comprises the steps: arranging a plurality of discrete electro-optic phase modulation segments on upper and lower interference arms of a Mach-Zehnder modulator; complementary doped isolation regions are inserted between the discrete electro-optic phase modulation segments; applying a dynamic reverse bias voltage to the complementary doped isolation region, and optimizing the bias voltage to balance the isolation performance and the modulation efficiency; acquiring the amplitude, phase, eye pattern and inter-symbol crosstalk of the output optical signal through a monitoring detector; pre-defining a mapping relation table of driving voltage and modulation output, and quickly adjusting a segmented driving signal and an isolation area bias voltage through a lookup table; driving signals of all sections are dynamically optimized in combination with an LMS self-adaptive algorithm, and process deviation and environment disturbance are compensated.

Description

Technical Field

[0001] The present invention relates to the technical field of optical signal modulation, and specifically to a multi-segment MZM closed-loop control system and method based on dynamic electric field regulation. Background Art

[0002] As a core device for realizing optical signal modulation in an optical communication system, the performance of a Mach-Zehnder modulator (MZM) directly affects the transmission rate and stability of optical communication.

[0003] Traditional Mach-Zehnder modulators face three main technical bottlenecks when realizing high-order modulation: First, the single-segment modulation structure is difficult to meet the multi-bit resolution requirements, resulting in limited modulation linearity; second, there are carrier diffusion and electric field crosstalk between modulation segments, seriously affecting the quality of high-frequency signals; third, environmental temperature changes and process deviations will introduce uncontrollable phase drift.

[0004] Existing solutions such as thermo-optic tuning compensation have a slow response speed, while pure electro-optic compensation is difficult to balance static deviation and dynamic disturbance. Although segmented MZMs can improve modulation accuracy through discrete driving, traditional isolation designs will generate leakage current during high-speed modulation, resulting in increased crosstalk between adjacent segments. Moreover, open-loop control schemes cannot compensate for modulation non-linearity caused by process inconsistency in real time. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-segment MZM closed-loop control system and method based on dynamic electric field regulation to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A multi-segment MZM closed-loop control method based on dynamic electric field regulation, the method comprising:

[0007] S100, input an optical signal into a chip through an input optical port, and divide the optical signal into two paths through a beam splitter, and respectively enter the upper and lower interference arms of a Mach-Zehnder modulator;

[0008] S200, arrange a plurality of discrete electro-optic phase modulation segments on the upper and lower interference arms of the Mach-Zehnder modulator; the discrete electro-optic phase modulation segments adopt a non-uniform length design and are independently driven, and complementary doped isolation regions are inserted between the discrete electro-optic phase modulation segments;

[0009] S300, apply a dynamic reverse bias voltage to the complementary doped isolation region, and optimize the bias voltage according to the modulation frequency and signal amplitude to balance the isolation performance and modulation efficiency;

[0010] S400, combine the two modulated optical signals through a combiner, and output the optical signal to a monitoring detector and a driving voltage control unit through an output optical port;

[0011] S500. Obtain the amplitude, phase, eye diagram, and inter-symbol interference of the output optical signal through a monitoring detector, and feedback the error signal to the drive voltage control unit;

[0012] S600. Pre-define a mapping relationship table between the drive voltage and the modulation output, and quickly adjust the segmented drive signal and the isolation region bias voltage by looking up the table; Combine the LMS adaptive algorithm to dynamically optimize each segmented drive signal to compensate for process deviations and environmental disturbances.

[0013] According to the above scheme, the discrete electro-optic phase modulation segments are arranged in sequence along the optical waveguide axis, and independent drive electrodes are configured to complete voltage or current control, which is compatible with the photoelectric effect, thermo-optic effect, or carrier dispersion effect;

[0014] The lengths of the discrete electro-optic phase modulation segments are non-uniformly distributed according to a preset ratio, and the non-uniform distribution is binary weight or thermometer coding to adapt to the modulation requirements of different bit resolutions;

[0015] The complementary doped isolation region is composed of materials with a doping type opposite to that of the adjacent segments, forming a PN junction or PIN junction structure, and a high-impedance depletion layer is formed by reverse biasing to block the leakage current path between the segments; The doping concentration, geometric shape, and depth of the complementary doped isolation region are adapted to the waveguide cross-section size.

[0016] According to the above scheme, step S300 includes:

[0017] S310. Apply a reverse bias voltage to the complementary doped isolation region through an external bias circuit to make the PN junction or PIN junction of the complementary doped isolation region in a reverse bias state, forming a high-impedance depletion layer;

[0018] S320. Adjust the amplitude of the bias voltage according to the modulation frequency. When it is high-frequency modulation, increase the voltage amplitude to broaden the depletion layer and enhance the suppression ability of carrier migration and parasitic capacitance coupling. When it is low-frequency modulation, reduce the voltage amplitude to avoid excessive broadening of the depletion layer affecting the optical waveguide modulation efficiency;

[0019] S330. Dynamically balance the isolation performance and modulation efficiency according to the real-time signal amplitude. When the signal amplitude is large, optimize the voltage so that the depletion layer can block the leakage current and maintain the carrier modulation concentration; When the signal amplitude is small, reduce the voltage to reduce power consumption and maintain the basic isolation effect;

[0020] S340. Optimize the voltage gradient and range according to the geometric size, segment spacing, and doping concentration characteristics of the complementary doped region to adapt to the electric field distribution requirements of the waveguide cross-section.

[0021] According to the above scheme, step S500 includes:

[0022] S510, obtaining a real-time waveform of the output optical signal through a high-speed photodetector, and obtaining the amplitude, phase, eye diagram, and inter-symbol crosstalk of the real-time waveform;

[0023] S520: Compare the real-time signal with the ideal reference signal and extract the error signal. The formula is as follows:

[0024] e=S ref -S out ;

[0025] Where, e represents the error signal; S ref Represents the ideal reference signal; S out It represents the optical signal collected and output by the high-speed photodetector; the error signal includes amplitude error, phase error, eye closure and inter-symbol crosstalk indicators;

[0026] S530. Use the mean square error to obtain an error evaluation. The formula is as follows:

[0027]

[0028] Where MSE represents the error evaluation; N represents the number of sampling points in the current evaluation window; j represents the index of the sampling point;

[0029] S540 , converting the analog signal output by the high-speed photodetector into a digital error signal through a high-speed analog-to-digital converter, and transmitting the digital error signal to the driving voltage control unit.

[0030] According to the above solution, step S600 includes:

[0031] S610, extracting the target parameter to be compensated based on the error signal and error evaluation fed back by the monitoring detector, querying the mapping relationship table between the driving voltage and the modulation output, and retrieving the corresponding voltage adjustment amount;

[0032] S620: Adaptively adjust the driving voltage of each electro-optical phase modulation segment using an LMS algorithm. The formula is as follows:

[0033]

[0034] in, It is represented as the driving voltage of the i-th segment modulator in the t-th control cycle; It represents the updated driving voltage under the current error feedback; t represents the index of the current control cycle; μ represents the learning rate, which is used to control the step size of the voltage update; e represents the error signal; It is expressed as the sensitivity of the output optical signal to the modulation segment voltage;

[0035] S630. To compensate for the slow phase drift, analyze the slow phase drift on the interferometer modulation path, and based on the slow phase drift on the interferometer modulation path, obtain the heater power adjustment value. The formula is as follows:

[0036]

[0037] Wherein, represents the adjusted heating power applied to the thermo-optic modulator; represents the heating power currently applied to the thermo-optic modulator; α represents the thermo-optic sensitivity coefficient; Δφ global represents the slow phase drift on the interferometer modulation path;

[0038] S640. Repeat the above optimization adjustment. When the error evaluation is lower than the error threshold, or the error signal shows no obvious improvement in multiple rounds of iteration, terminate the iteration and output the final control voltage value.

[0039] According to the above scheme, the mapping relationship table between the drive voltage and the modulation output includes:

[0040] On the upper and lower interference arms of the Mach-Zehnder modulator, a total of M discrete electro-optic phase modulation segments are arranged, and the length ratio of each electro-optic phase modulation segment is L1:L2:…:L M ;

[0041] The maximum phase shift capacity of each segment, the formula is as follows:

[0042] φ i max =L i ×η;

[0043] Wherein, φ i max represents the maximum phase shift capacity of each segment; η represents the modulation efficiency per unit length of each segment; i represents the index of the electro-optic phase modulation segment;

[0044] The input control code is D = b M-1 , b M-2 ,…, b i ,…, b0; wherein, b i represents the i-th bit value in the input control code, and b i ∈{0,1}, i represents the index of the electro-optic phase modulation segment;

[0045] For the i-th segment, the mapping rule of the modulation voltage, the formula is as follows:

[0046]

[0047] Wherein, V i represents the modulation voltage. When bi When b π = 1, it indicates that the corresponding weight segment is enabled, and the i-th segment modulator applies the driving voltage V π , where V i represents the driving voltage corresponding to the required π phase; when b

[0048] The overall phase shift is obtained by superimposing the phase shifts of each segment, and the formula is as follows:

[0049]

[0050] where φ total represents the overall phase shift; φ i max represents the maximum phase shift ability of each segment; M represents the total number of input control codes.

[0051] According to the above scheme, the slow phase drift includes:

[0052] Establish an ideal output light intensity look-up table, and the formula is as follows:

[0053]

[0054] where LUT represents the ideal output light intensity look-up table; D represents the input control code; Δφ ideal represents the corresponding ideal phase difference; I0 represents the input optical power; I ref (D) represents the target value;

[0055] Calculate the phase difference corresponding to the actual output light intensity, and the formula is as follows:

[0056]

[0057] where Δφ real represents the phase difference corresponding to the actual output light intensity, and I meas represents the actual output light intensity;

[0058] Calculate the ideal phase difference corresponding to the ideal output light intensity, and the formula is as follows:

[0059]

[0060] where Δφ ideal represents the ideal phase difference corresponding to the ideal output light intensity, and I ideal represents the ideal output light intensity in the ideal output light intensity look-up table;

[0061] Based on the phase difference corresponding to the actual output light intensity and the ideal phase difference corresponding to the ideal output light intensity, obtain the current phase drift amount, and the formula is as follows:

[0062] δΔφ global = Δφ real -Δφ ideal ;

[0063] wherein, δΔφ global represents the current phase drift amount, which is used to reflect the degree of phase drift.

[0064] A multi-segment MZM closed-loop control system based on dynamic electric field regulation, the system includes: an optical signal input module, a Mach-Zehnder modulator module, an electric field regulation module, a monitoring and detection module, a drive control module, and a closed-loop control module;

[0065] The optical signal input module is used to provide an optical signal input channel, and evenly divides the optical signal into two paths through a beam splitter, and inputs them into the upper and lower interference arms of the Mach-Zehnder modulator respectively;

[0066] The Mach-Zehnder modulator module realizes the phase or amplitude modulation output of the optical signal through multi-segment independent modulation and interference effects;

[0067] The electric field regulation module generates and adjusts the driving voltage and the bias voltage to realize the electric field control of the modulation segment and the isolation region;

[0068] The monitoring and detection module monitors the amplitude, phase, eye diagram and inter-symbol interference of the output optical signal in real time, extracts the error signal and error evaluation, and feeds them back to the closed-loop control module;

[0069] The closed-loop control module loads the initial driving parameters from the mapping relationship table of the predefined driving voltage and modulation output, and dynamically optimizes them through an adaptive algorithm;

[0070] The drive control module converts the initial parameters provided by the closed-loop control module into an analog drive signal and applies it to the segmented electrodes and isolation regions in the Mach-Zehnder modulator module.

[0071] According to the above solution, the closed-loop control module includes a look-up table module, an optimization parameter module, and a thermo-optic compensation control module; the look-up table module stores the mapping relationship between the driving voltage and the modulation output, and completes the dynamic compensation of the segmented driving signal and the bias voltage of the isolation region by querying and calling the predefined voltage adjustment parameters; the optimization parameter module dynamically optimizes the driving voltage of each segment based on the real-time error signal, compensates for process deviations and environmental disturbances, and realizes the dynamic adjustment of the closed-loop control; the thermo-optic compensation control module calculates the slow phase drift, adjusts the phase of the interferometer path through the thermo-optic effect, and realizes the thermo-optic compensation control.

[0072] According to the above solution, the Mach-Zehnder modulator module includes upper and lower interference arms, discrete electro-optic modulation segments, and complementary doping isolation regions; a plurality of discrete electro-optic phase modulation segments are arranged on the upper and lower interference arms, and the electro-optic phase modulation segments adopt a non-uniform length design; the complementary doping isolation regions are inserted between the optical phase modulation segments, and a high-impedance depletion layer is formed by reverse biasing to block leakage current.

[0073] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0074] 1. The present invention realizes high-precision modulation of optical signals through discrete electro-optic phase modulation segments with non-uniform length design and dynamic electric field regulation;

[0075] 2. The present invention combines the LMS algorithm with a look-up table to dynamically optimize the driving voltage of each segment, and can effectively compensate for process deviations and environmental disturbances;

[0076] 3. Based on the slow phase drift amount, the present invention uses a thermo-optic modulator to dynamically adjust the heating power to ensure that the system can work stably under various environmental conditions. Description of the Drawings

[0077] Figure 1 It is a flowchart of the steps of the multi-segment MZM closed-loop control method based on dynamic electric field regulation of the present invention;

[0078] Figure 2 It is a schematic structural diagram of the multi-segment MZM closed-loop control system based on dynamic electric field regulation of the present invention;

[0079] Figure 3 It is a schematic structural diagram of a segmented electro-optic modulator with an NPN-type structure configuration of the multi-segment MZM closed-loop control method based on dynamic electric field regulation of the present invention;

[0080] Figure 4 It is a schematic structural diagram of a Mach-Zehnder modulator with a complementary doping isolation structure of the multi-segment MZM closed-loop control method based on dynamic electric field regulation of the present invention. Detailed Embodiments

[0081] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0082] Embodiment: As Figures 1-4 shown, the present invention provides a technical solution, a multi-segment MZM closed-loop control method based on dynamic electric field regulation, and the method includes the steps:

[0083] S100. Input an optical signal into the chip through the input optical port, and divide the optical signal into two paths through a beam splitter, and enter the upper and lower interference arms of the Mach-Zehnder modulator respectively;

[0084] S200. Arrange a plurality of discrete electro-optic phase modulation segments on the upper and lower interference arms of the Mach-Zehnder modulator; the discrete electro-optic phase modulation segments adopt a non-uniform length design and are independently driven, and complementary doped isolation regions are inserted between the discrete electro-optic phase modulation segments;

[0085] Specifically, the discrete electro-optic phase modulation segments are arranged in sequence along the optical waveguide axis, and independent drive electrodes are configured to complete voltage or current control, and are compatible with the photoelectric effect, thermo-optic effect or carrier dispersion effect;

[0086] The lengths of the discrete electro-optic phase modulation segments are non-uniformly distributed according to a preset ratio, and the non-uniform distribution is binary weight or thermometer coding to adapt to the modulation requirements of different bit resolutions;

[0087] The complementary doped isolation region is composed of materials with a doping type opposite to that of the adjacent segments, forms a PN junction or PIN junction structure, and forms a high-impedance depletion layer through reverse biasing to block the leakage current path between the segments; the doping concentration, geometric shape and depth of the complementary doped isolation region are adapted to the waveguide cross-section size.

[0088] S300. Apply a dynamic reverse bias voltage to the complementary doped isolation region, and optimize the bias voltage according to the modulation frequency and signal amplitude to balance the isolation performance and modulation efficiency;

[0089] Specifically, step S300 includes:

[0090] S310. Apply a reverse bias voltage to the complementary doped isolation region through an external bias circuit to make the PN junction or PIN junction of the complementary doped isolation region in a reverse bias state, forming a high-impedance depletion layer;

[0091] S320. Adjust the amplitude of the bias voltage according to the modulation frequency. When it is high-frequency modulation, increase the voltage amplitude to broaden the depletion layer and enhance the suppression ability of carrier migration and parasitic capacitance coupling. When it is low-frequency modulation, reduce the voltage amplitude to avoid excessive broadening of the depletion layer affecting the optical waveguide modulation efficiency;

[0092] S330. Dynamically balance the isolation performance and modulation efficiency according to the real-time signal amplitude. When the signal amplitude is large, optimize the voltage so that the depletion layer can block the leakage current and maintain the carrier modulation concentration; when the signal amplitude is small, reduce the voltage to reduce power consumption and maintain the basic isolation effect;

[0093] S340. Optimize the voltage gradient and range according to the geometric dimensions, segment spacing, and doping concentration characteristics of the complementary doping region to adapt to the electric field distribution requirements of the waveguide cross-section.

[0094] S400. The two modulated optical signals are combined by a beam combiner, and the optical signal is output through the output optical port to the monitoring detector and the drive voltage control unit;

[0095] S500. Obtain the amplitude, phase, eye diagram, and inter-symbol interference of the output optical signal through the monitoring detector, and feedback the error signal to the drive voltage control unit;

[0096] Specifically, step S500 includes:

[0097] S510. Obtain the real-time waveform of the output optical signal through a high-speed photodetector, and obtain the amplitude, phase, eye diagram, and inter-symbol interference of the real-time waveform;

[0098] S520. Compare the real-time signal with the ideal reference signal, and extract the error signal. The formula is as follows:

[0099] e = S ref -S out ;

[0100] where e represents the error signal; S ref represents the ideal reference signal; S out represents the optical signal collected and output by the high-speed photodetector; the error signal includes amplitude error, phase error, eye diagram closure, and inter-symbol interference index;

[0101] S530. Use the mean square error to obtain the error evaluation. The formula is as follows:

[0102]

[0103] where MSE represents the error evaluation; N represents the number of sampling points within the current evaluation window; j represents the index of the sampling point;

[0104] S540. Convert the analog signal output by the high-speed photodetector into a digital error signal through a high-speed analog-to-digital converter, and transmit the digital error signal to the drive voltage control unit.

[0105] S600. The drive voltage control unit predefines the mapping relationship table between the drive voltage and the modulation output, and quickly adjusts the segmented drive signal and the isolation region bias voltage through the look-up table; combine the LMS adaptive algorithm to dynamically optimize each segmented drive signal to compensate for process deviations and environmental disturbances;

[0106] Specifically, step S600 includes:

[0107] S610. Extract the target parameters to be compensated according to the error signal and error evaluation fed back by the monitoring detector, query the mapping relationship table between the drive voltage and the modulation output, and retrieve the corresponding voltage adjustment amount.

[0108] Further, the mapping relationship table between the drive voltage and the modulation output includes:

[0109] On the upper and lower interference arms of the Mach-Zehnder modulator, a total of M discrete electro-optic phase modulation segments are arranged, and the length ratios of each electro-optic phase modulation segment are L1:L2:…:L M ;

[0110] The maximum phase shift capacity of each segment is as follows:

[0111] φ i max = L i ×η;

[0112] Among them, φ i max represents the maximum phase shift capacity of each segment; η represents the modulation efficiency per unit length of each segment; i represents the index of the electro-optic phase modulation segment.

[0113] The input control code is D = b M-1 , b M-2 , …, b i , …, b0; where b i represents the i-th bit value in the input control code, and b i ∈{0,1}, and i represents the index of the electro-optic phase modulation segment.

[0114] For the i-th segment, the mapping rule of the modulation voltage is as follows:

[0115]

[0116] Among them, V i represents the modulation voltage. When b i = 1, it means that the corresponding weight segment is enabled, and the i-th segment modulator applies the drive voltage V π , and V π represents the drive voltage corresponding to the required π phase; when b i = 0, it means that the corresponding weight segment is not enabled, and the drive voltage of the i-th segment modulator is 0.

[0117] The overall phase shift is obtained by superimposing the phase shifts of each segment, and the formula is as follows:

[0118]

[0119] Among them, φ total represents the overall phase shift; φi max is expressed as the maximum phase shift capability per segment; M is expressed as the total number of input control codes.

[0120] S620. Use the LMS algorithm to adaptively adjust the driving voltage of each electro-optic phase modulation segment. The formula is as follows:

[0121]

[0122] where is expressed as the driving voltage of the i-th segment modulator under the t-th control cycle; is expressed as the updated driving voltage under the current error feedback; t is expressed as the index of the current control period; μ is expressed as the learning rate, which is used to control the step size of voltage update; e is expressed as the error signal; is expressed as the sensitivity of the output optical signal to the modulation segment voltage;

[0123] S630. To compensate for slow phase drift, analyze the slow phase drift on the interferometer modulation path, and obtain the heater power adjustment value based on the slow phase drift on the interferometer modulation path. The formula is as follows:

[0124]

[0125] where is expressed as the adjusted heating power applied to the thermo-optic modulator is expressed as the heating power currently applied to the thermo-optic modulator; α is expressed as the thermo-optic sensitivity coefficient; Δφ global is expressed as the slow phase drift on the interferometer modulation path;

[0126] Furthermore, the slow phase drift includes:

[0127] Establish an ideal output optical intensity look-up table. The formula is as follows:

[0128]

[0129] where LUT is expressed as the ideal output optical intensity look-up table; D is expressed as the input control code; Δφ ideal is expressed as the corresponding ideal phase difference; I0 is expressed as the input optical power; I ref (D) is expressed as the target value;

[0130] Calculate the phase difference corresponding to the actual output optical intensity. The formula is as follows:

[0131]

[0132] where Δφ real is expressed as the phase difference corresponding to the actual output optical intensity, I measIt is expressed as the actual output optical intensity;

[0133] Calculate the ideal phase difference corresponding to the ideal output optical intensity. The formula is as follows:

[0134]

[0135] Among them, Δφ ideal is expressed as the ideal phase difference corresponding to the ideal output optical intensity, and I ideal is expressed as the ideal output optical intensity in the ideal output optical intensity look-up table;

[0136] Based on the phase difference corresponding to the actual output optical intensity and the ideal phase difference corresponding to the ideal output optical intensity, obtain the current phase drift amount. The formula is as follows:

[0137] δΔφ global = Δφ real - Δφ ideal ;

[0138] Among them, δΔφ global is expressed as the current phase drift amount, which is used to reflect the degree of phase drift.

[0139] S640. Repeat the above optimization and adjustment. When the error evaluation is lower than the error threshold, or the error signal shows no obvious improvement within the pair iteration, terminate the iteration and output the final control voltage value.

[0140] The present invention provides another technical solution, a multi-segment MZM closed-loop control method based on dynamic electric field regulation, and a segmented electro-optic modulator configured with an NPN structure;

[0141] As Figure 3 shown, the segmented electro-optic modulator configured with an NPN structure includes an N++ doped region 100, an N++ doped region 900, an N doped region 200, an N doped region 800, a waveguide region 300, a waveguide region 800, a P doped region 400, a P doped region 600, a P++ doped region 500, a complementary doped isolation region 110, a complementary doped isolation region 120, and a complementary doped isolation region 130;

[0142] The N++ doped region 100 and the N++ doped region 900 are respectively located at both ends of the entire modulator structure, and are used to form ohmic contact regions with low contact resistance, serving as the connection interfaces for external drive electrodes;

[0143] The N doped region 200 and the N doped region 800 are respectively arranged between the N++ doped region and the waveguide region, serving as transition regions for electric field regulation, facilitating the uniform distribution of the electric field in the modulation region and participating in the electro-optic modulation effect;

[0144] The waveguide regions 300 and 800 are respectively the upper and lower arm optical waveguide regions of the Mach-Zehnder modulator, located at the center of the modulator, and are used to guide and carry the input optical signal;

[0145] The P-doped regions 400 and 600 are respectively arranged at corresponding positions of the upper and lower waveguide regions, and are used to form a PN junction structure with the n-type doped region to modulate the optical refractive index;

[0146] The P++-doped region 500 is located in the center of the p-doped region, forming a good p-region metal contact area, improving the carrier injection efficiency, and thus enhancing the modulation depth;

[0147] The complementary doped isolation regions 110, 120, and 130 are composed of materials with a doping type opposite to that of the adjacent modulation segments. A P-type doped region is introduced between adjacent N-type modulation regions to form a high-resistance isolation region; the P++-type doping is continued between adjacent P-type modulation regions to maintain conductivity. The isolation region forms a back-to-back PN junction structure through reverse biasing. During operation, one of the PN junctions is in a reverse-biased state, and the depletion layer exhibits a megaohm-level high-resistance characteristic, effectively suppressing carrier diffusion and leakage current.

[0148] The present invention provides another technical solution, a multi-segment MZM closed-loop control method based on dynamic electric field regulation, a Mach-Zehnder modulator with a complementary doped isolation structure;

[0149] An optical signal is input into the chip through the input optical port, and the optical signal is divided into two paths by a beam splitter and enters the upper and lower interference arms of the Mach-Zehnder modulator respectively; a plurality of discrete electro-optic phase modulation segments are arranged on the upper and lower interference arms of the Mach-Zehnder modulator; the discrete electro-optic phase modulation segments adopt a non-uniform length design and are independently driven, and complementary doped isolation regions are inserted between the discrete electro-optic phase modulation segments;

[0150] Specifically, the discrete electro-optic phase modulation segments are arranged in sequence along the optical waveguide axis and are configured with independent drive electrodes to complete voltage or current control, compatible with the photoelectric effect, thermo-optic effect or carrier dispersion effect; the lengths of the discrete electro-optic phase modulation segments are non-uniformly distributed according to a preset ratio, and the non-uniform distribution is binary weight or thermometer coding to adapt to the modulation requirements of different bit resolutions; the complementary doped isolation region is composed of materials with a doping type opposite to that of the adjacent segments, forming a PN junction or PIN junction structure, and forming a high-impedance depletion layer through reverse biasing to block the leakage current path between the segments; the doping concentration, geometric shape and depth of the complementary doped isolation region are adapted to the waveguide cross-section size.

[0151] Such as Figure 4As shown, the Mach-Zehnder modulator of the complementary doping isolation structure includes an input optical port 1, a thermo-optical phase modulator 2, a first electro-optical phase modulation segment 3, a first complementary doping isolation region 4, a second electro-optical phase modulation segment 5, a second complementary doping isolation region 6, a third electro-optical phase modulation segment 7, a third complementary doping isolation region 8, a fourth electro-optical phase modulation segment 9, an output optical port 10 and a monitoring detector 11;

[0152] The input optical port 1 is used to receive the input optical signal, including the input optical waveguide and coupling port;

[0153] Thermo-optical phase modulator 2 is set at the front section of the interferometer arm and is used to adjust the initial phase, as well as bias point control or temperature stabilization control;

[0154] Four discrete electro-optical phase modulation segments are arranged on the upper and lower interferometer arms of the Mach-Zehnder modulator, namely a first electro-optical phase modulation segment 3, a second electro-optical phase modulation segment 5, a third electro-optical phase modulation segment 7 and a fourth electro-optical phase modulation segment 9;

[0155] The first electro-optical phase modulation segment 3 is the first carrier depletion or injection electro-optical modulator, which is used to perform the first stage of high-speed modulation of the optical signal; the second electro-optical phase modulation segment 5, the third electro-optical phase modulation segment 7 and the fourth electro-optical phase modulation segment 9 continue to perform the high-speed phase modulation task; the fourth electro-optical phase modulation segment 9 is the last segment at the end of the interferometer arm;

[0156] Complementary doped isolation regions are inserted between discrete electro-optical phase modulation segments. The complementary doped isolation regions include a first complementary doped isolation region 4, a second complementary doped isolation region 6, and a third complementary doped isolation region 8. The structure uses semiconductor materials with opposite doping types to adjacent modulation segments to form a PN junction or PIN junction structure for electrical isolation and crosstalk reduction, thereby improving modulation performance.

[0157] The first complementary doped isolation region 4 is disposed between the first and second electro-optical phase modulation segments, the second complementary doped isolation region 6 is disposed between the second and third electro-optical phase modulation segments, and the third complementary doped isolation region 8 is disposed between the third and fourth electro-optical phase modulation segments;

[0158] The output optical port 10 is used to output the modulated optical signal, including an output optical waveguide and a coupling port;

[0159] The monitoring detector 11 is used to monitor the modulated optical signal.

[0160] The present invention provides another technical solution, a multi-segment MZM closed-loop control method based on dynamic electric field regulation, and a Mach-Zehnder modulator with a 1:2:3:4 length ratio segmented structure, which is applied to a 4-bit digital code phase modulation scenario;

[0161] The input 4-bit digital code is D = b3b2b1b0; and b i ∈{0,1} (i = 0,1,2,3), where i represents the index of the electro-optic phase modulation segments;

[0162] The length ratios of each electro-optic phase modulation segment are L1:L2:L3:L4 = 1:2:3:4, and the modulation efficiency per unit length is η; the maximum phase shift capacity φ of each segment i max = η×L i ;

[0163] The driving voltage V i , when b i = 1, V i = V π , when b i = 0, V i = 0;

[0164] Establish an ideal output optical intensity look-up table, and the formula is as follows:

[0165]

[0166] where LUT represents the ideal output optical intensity look-up table; D represents the input control code; Δφ ideal represents the corresponding ideal phase difference; I0 represents the input optical power; I ref (D) represents the target value;

[0167] For the 4 electro-optic phase modulation segments, apply different combinations of driving voltages in sequence, and measure the phase shift and optical intensity of the corresponding output optical signal; for example: when the input digital code is 0001, only apply V π voltage to the first segment, and measure and record the output phase and optical intensity;

[0168] Establish the mapping between the input digital code b3b2b1b0 and the driving voltages V1, V2, V3, V4 of each segment. The mapping rule of the modulation voltage is as follows:

[0169]

[0170] where V i represents the modulation voltage. When b i = 1, it means that the corresponding weighted segment is enabled, and the i-th segment modulator is applied with the driving voltage V π , V π represents the driving voltage corresponding to the required π phase; when b i = 0, it means that the corresponding weighted segment is not enabled, and the driving voltage of the i-th segment modulator is 0;

[0171] Calculate and store the ideal output optical intensity I corresponding to the input digital code ref , construct an ideal output optical intensity look-up table. For example: when the input digital code is 0001, the corresponding ideal phase difference is Δφ ideal is η×1, I ref = i0cos(η×1 / 2);

[0172] Compare the real-time signal with the ideal reference signal to extract the error signal. The formula is as follows:

[0173] e = S ref - S out ;

[0174] where e represents the error signal; S ref represents the ideal reference signal; S out represents the optical signal collected and output by the high-speed photodetector; the error signal includes amplitude error, phase error, eye diagram closure degree, and inter-symbol interference index;

[0175] Use the mean square error to obtain the error evaluation. The formula is as follows:

[0176]

[0177] where MSE represents the error evaluation; N represents the number of sampling points within the current evaluation window; j represents the index of the sampling point;

[0178] Retrieve the drive voltage look-up table, and obtain the drive voltage adjustment amount for each segment according to the input digital code and the error parameter. For example, if the phase shift is due to insufficient modulation in the second segment and the input code corresponds to b2 = 1, then adjust V2 to approach V π , to compensate for the phase deviation.

[0179] Set the initial drive voltage V t i = LUT(b i ), where t represents the index of the current control cycle, the learning rate μ, for example, initially 0.01, needs to be adjusted according to the convergence speed and stability;

[0180] Use the LMS algorithm to adaptively adjust the drive voltage for each electro-optic phase modulation segment. The formula is as follows:

[0181]

[0182] where represents the drive voltage of the i-th segment modulator in the t-th control cycle; represents the updated drive voltage under the current error feedback; t represents the index of the current control cycle; μ represents the learning rate, which is used to control the step size of voltage update; e represents the error signal; It is expressed as the sensitivity of the output optical signal to the modulation section voltage;

[0183] To compensate for the slow phase drift, analyze the slow phase drift on the modulation path of the interferometer, and based on the slow phase drift on the modulation path of the interferometer, obtain the heater power adjustment value. The formula is as follows:

[0184]

[0185] Where, It is expressed as the adjusted heating power applied to the thermo-optic modulator; It is expressed as the heating power currently applied to the thermo-optic modulator; α is expressed as the thermo-optic sensitivity coefficient; Δφ global It is expressed as the slow phase drift on the modulation path of the interferometer;

[0186] Repeat the above optimization adjustment, when the error evaluation is lower than the error threshold, or when the error signal shows no obvious improvement in multiple rounds of iteration, then terminate the iteration and output the final control voltage value.

[0187] The present invention provides another technical solution, a multi-segment MZM closed-loop control system based on dynamic electric field regulation. The system includes: an optical signal input module, a Mach-Zehnder modulator module, an electric field regulation module, a monitoring and detection module, a drive control module, and a closed-loop control module;

[0188] The optical signal input module is used to provide an optical signal input channel, evenly divide the optical signal into two paths through a beam splitter, and respectively input them into the upper and lower interference arms of the Mach-Zehnder modulator; the Mach-Zehnder modulator module realizes the phase or amplitude modulation output of the optical signal through multi-segment independent modulation and interference effects; the electric field regulation module generates and adjusts the drive voltage and the bias voltage to realize the electric field control of the modulation section and the isolation area; the monitoring and detection module monitors the amplitude, phase, eye diagram, and inter-symbol interference of the output optical signal in real time, extracts the error signal and the error evaluation, and feeds them back to the closed-loop control module; the closed-loop control module loads the initial drive parameters from the pre-defined mapping relationship table between the drive voltage and the modulation output, and dynamically optimizes them through an adaptive algorithm; the drive control module converts the initial parameters provided by the closed-loop control module into an analog drive signal and applies it to the segmented electrodes and the isolation area in the Mach-Zehnder modulator module.

[0189] The closed-loop control module includes a look-up table module, an optimized parameter module, and a thermo-optic compensation control module; the look-up table module stores the mapping relationship between the driving voltage and the modulation output, and completes the dynamic compensation of the segmented driving signal and the bias voltage of the isolation region by querying and calling the predefined voltage adjustment parameters; the optimized parameter module dynamically optimizes the segmented driving voltages based on the real-time error signal through an adaptive algorithm, compensates for process deviations and environmental disturbances, and realizes the dynamic adjustment of the closed-loop control; the thermo-optic compensation control module calculates the slow phase drift and adjusts the phase of the interferometer path through the thermo-optic effect to realize the thermo-optic compensation control.

[0190] The Mach-Zehnder modulator module includes upper and lower interference arms, discrete electro-optic modulation segments, and complementary doped isolation regions; a plurality of discrete electro-optic phase modulation segments are arranged on the upper and lower interference arms, and the electro-optic phase modulation segments adopt a non-uniform length design; the complementary doped isolation regions are inserted between the optical phase modulation segments, and a high-impedance depletion layer is formed by reverse biasing to block the leakage current.

[0191] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A closed-loop control method for a multi-segment MZM based on dynamic electric field regulation, characterized in that, The method includes: S100. Input an optical signal into the chip through an input optical port, and divide the optical signal into two paths through a beam splitter, and enter the upper and lower interference arms of the Mach-Zehnder modulator respectively; S200. Arrange a plurality of discrete electro-optic phase modulation segments on the upper and lower interference arms of the Mach-Zehnder modulator; the discrete electro-optic phase modulation segments adopt a non-uniform length design and are independently driven, and complementary doped isolation regions are inserted between the discrete electro-optic phase modulation segments; S300. Apply a dynamic reverse bias voltage to the complementary doped isolation region, and optimize the bias voltage according to the modulation frequency and signal amplitude to balance the isolation performance and modulation efficiency; S400. The two modulated optical signals are combined through a combiner, and the optical signal is output through an output optical port to a monitoring detector and a drive voltage control unit; S500. Obtain the amplitude, phase, eye diagram and inter-symbol interference of the output optical signal through the monitoring detector, and feedback the error signal to the drive voltage control unit; S600. Pre-define a mapping relationship table between the drive voltage and the modulation output, and quickly adjust the segmented drive signal and the isolation region bias voltage through a look-up table; combine the LMS adaptive algorithm to dynamically optimize each segmented drive signal to compensate for process deviations and environmental disturbances.

2. The multi-segment MZM closed-loop control method based on dynamic electric field regulation according to claim 1, characterized in that: The discrete electro-optic phase modulation segments are arranged in sequence along the optical waveguide axis and are configured with independent drive electrodes to complete voltage or current control, and are compatible with the photoelectric effect, thermo-optic effect or carrier dispersion effect; The lengths of the discrete electro-optic phase modulation segments are non-uniformly distributed according to a preset ratio, and the non-uniform distribution is binary weight or thermometer coding to adapt to the modulation requirements of different bit resolutions; The complementary doped isolation region is composed of materials with doping types opposite to those of adjacent segments, forms a PN junction or PIN junction structure, and forms a high-impedance depletion layer through reverse bias to block the leakage current path between segments; the doping concentration, geometric shape and depth of the complementary doped isolation region are adapted to the waveguide cross-section size.

3. The multi-segment MZM closed-loop control method based on dynamic electric field regulation according to claim 1, characterized in that: Step S300 includes: S310. Apply a reverse bias voltage to the complementary doped isolation region through an external bias circuit to make the PN junction or PIN junction of the complementary doped isolation region in a reverse bias state, forming a high-impedance depletion layer; S320. Adjust the amplitude of the bias voltage according to the modulation frequency. When it is high-frequency modulation, increase the voltage amplitude to broaden the depletion layer and enhance the suppression ability of carrier migration and parasitic capacitance coupling. When it is low-frequency modulation, reduce the voltage amplitude to avoid excessive broadening of the depletion layer affecting the optical waveguide modulation efficiency; S330. Dynamically balance the isolation performance and modulation efficiency according to the real-time signal amplitude. When it is a large signal amplitude, optimize the voltage so that the depletion layer can block the leakage current and maintain the carrier modulation concentration; when it is a small signal amplitude, reduce the voltage to reduce power consumption and maintain the basic isolation effect; S340. Optimize the voltage gradient and range according to the geometric size, segment spacing and doping concentration characteristics of the complementary doped region to adapt to the electric field distribution requirements of the waveguide cross-section.

4. The multi-segment MZM closed-loop control method based on dynamic electric field regulation according to claim 1, characterized in that: Step S500 includes: S510. Obtain the real-time waveform of the output optical signal through a high-speed photodetector, and obtain the amplitude, phase, eye diagram, and inter-symbol interference of the real-time waveform; S520. Compare the real-time signal with the ideal reference signal to extract the error signal. The formula is as follows: e = S ref -S out ; where e represents the error signal; S ref represents the ideal reference signal; S out represents the optical signal collected and output by the high-speed photodetector; the error signal includes amplitude error, phase error, eye diagram closure, and inter-symbol interference index; S530. Use the mean square error to obtain the error evaluation. The formula is as follows: Where, MSE represents the error evaluation; N represents the number of sampling points within the current evaluation window; j represents the index of the sampling point; S540. Convert the analog signal output by the high-speed photodetector into a digital error signal through a high-speed analog-to-digital converter, and transmit the digital error signal to the drive voltage control unit.

5. The multi-segment MZM closed-loop control method based on dynamic electric field regulation according to claim 1, characterized in that: Step S600 includes: S610. According to the error signal and error evaluation feedback by the monitoring detector, extract the target parameters to be compensated, query the mapping relationship table between the drive voltage and the modulation output, and retrieve the corresponding voltage adjustment amount; S620. Use the LMS algorithm to adaptively adjust the drive voltage for each electro-optic phase modulation segment. The formula is as follows: Among them, represents the driving voltage of the i-th segment modulator under the t-th control cycle; represents the updated driving voltage under the current error feedback; t represents the index of the current control cycle; μ represents the learning rate, which is used to control the step size of voltage update; e represents the error signal; represents the sensitivity of the output optical signal to the modulation segment voltage; S630. To compensate for the slow phase drift, analyze the slow phase drift on the modulation path of the interferometer, and based on the slow phase drift on the modulation path of the interferometer, obtain the heater power adjustment value. The formula is as follows: Among them, is expressed as the adjusted heating power applied by the thermo-optic modulator is expressed as the heating power currently applied by the thermo-optic modulator; α is expressed as the thermo-optic sensitivity coefficient; Δφ global is expressed as the slow phase drift on the modulation path of the interferometer; S640. Repeat the above optimization adjustment. When the error evaluation is lower than the error threshold, or the error signal shows no obvious improvement within the pair of iterations, terminate the iteration and output the final control voltage value.

6. The multi-segment MZM closed-loop control method based on dynamic electric field regulation according to claim 5, wherein: The mapping relationship table between the drive voltage and the modulation output includes: On the upper and lower interference arms of the Mach-Zehnder modulator, a total of M discrete electro-optic phase modulation segments are arranged, and the length ratios of each electro-optic phase modulation segment are L1:L2:…:L M ; The maximum phase shift capacity of each segment. The formula is as follows: φ i max = L i × η; Among them, φ i max represents the maximum phase shift capacity per segment; η represents the modulation efficiency per unit length of each segment; i represents the index of the electro-optic phase modulation segments; The input control code is D = b M-1 , b M-2 , …, b i , …, b0; where b i represents the i-th bit value in the input control code, and b i ∈{0, 1}, and i represents the index of the electro-optic phase modulation segment; For the i-th segment, the mapping rule of the modulation voltage. The formula is as follows: Among them, V i is represented as the modulation voltage. When b i = 1, it means that the corresponding weight segment is enabled, and the i-th segment modulator applies the driving voltage V π , and V π is represented as the driving voltage corresponding to the required π phase; when b i = 0, it means that the corresponding weight segment is not enabled, and the driving voltage of the i-th segment modulator is 0; The overall phase shift is obtained by superimposing the phase shifts of each segment. The formula is as follows: Among them, φ total represents the overall phase shift; φ i max represents the maximum phase shift capacity per segment; M represents the total number of input control codes.

7. The multi-segment MZM closed-loop control method based on dynamic electric field regulation according to claim 5, wherein: The slow phase drift includes: Establish an ideal output optical intensity lookup table. The formula is as follows: Among them, LUT represents the ideal output light intensity look-up table; D represents the input control code; Δφ ideal represents the corresponding ideal phase difference; I0 represents the input optical power; I ref (D) represents the target value; Calculate the phase difference corresponding to the actual output optical intensity. The formula is as follows: Among them, Δφ real represents the phase difference corresponding to the actual output light intensity, and I meas represents the actual output light intensity; Calculate the ideal phase difference corresponding to the ideal output optical intensity. The formula is as follows: Among them, Δφ ideal represents the ideal phase difference corresponding to the ideal output light intensity, and I ideal represents the ideal output light intensity in the ideal output light intensity look-up table; Based on the phase difference corresponding to the actual output optical intensity and the ideal phase difference corresponding to the ideal output optical intensity, obtain the current phase drift amount. The formula is as follows: δΔφ global = Δφ real -Δφ ideal ; Among them, δΔφ global represents the current phase drift amount and is used to reflect the degree of phase drift.

8. A multi-segment MZM closed-loop control system based on dynamic electric field regulation, applied to the multi-segment MZM closed-loop control method based on dynamic electric field regulation according to any one of claims 1-7, characterized in that: The system includes: an optical signal input module, a Mach-Zehnder modulator module, an electric field regulation module, a monitoring detection module, a drive control module, and a closed-loop control module; The optical signal input module is used to provide an optical signal input channel, and evenly divide the optical signal into two paths through a beam splitter and input them into the upper and lower interference arms of the Mach-Zehnder modulator respectively; The Mach-Zehnder modulator module realizes the phase or amplitude modulation output of the optical signal through multi-segment independent modulation and interference effects; The electric field regulation module generates and adjusts the drive voltage and the bias voltage to realize the electric field control of the modulation segment and the isolation area; The monitoring detection module monitors the amplitude, phase, eye diagram, and inter-symbol interference of the output optical signal in real time, extracts the error signal and the error evaluation, and feeds them back to the closed-loop control module; The closed-loop control module loads the initial drive parameters from the predefined mapping relationship table between the drive voltage and the modulation output, and dynamically optimizes them through an adaptive algorithm; The driving control module converts the initial parameters provided by the closed-loop control module into analog driving signals and applies them to the segmented electrodes and isolation regions in the Mach-Zehnder modulator module.

9. The multi-segment MZM closed-loop control system based on dynamic electric field regulation according to claim 8, characterized in that: The closed-loop control module includes a look-up table module, an optimized parameter module, and a thermo-optic compensation control module; the look-up table module stores the mapping relationship between the driving voltage and the modulation output, and completes the dynamic compensation of the segmented driving signal and the isolation region bias voltage by querying and calling predefined voltage adjustment parameters; the optimized parameter module dynamically optimizes each segmented driving voltage based on the real-time error signal through an adaptive algorithm to compensate for process deviations and environmental disturbances, and realizes the dynamic adjustment of the closed-loop control; the thermo-optic compensation control module calculates the slow phase drift and adjusts the phase of the interferometer path through the thermo-optic effect to achieve thermo-optic compensation control.

10. The multi-segment MZM closed-loop control system based on dynamic electric field regulation according to claim 8, characterized in that: The Mach-Zehnder modulator module includes upper and lower interference arms, discrete electro-optic modulation segments, and complementary doped isolation regions; a plurality of discrete electro-optic phase modulation segments are arranged on the upper and lower interference arms, and the electro-optic phase modulation segments adopt a non-uniform length design; the complementary doped isolation regions are inserted between the optical phase modulation segments, and a high-impedance depletion layer is formed by reverse biasing to block leakage current.

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