Optical microcavity fpga miniaturization narrow linewidth laser optical multimodal locking system

Abstract

The application provides an optical microcavity FPGA miniaturized narrow linewidth laser optical multimodal locking system, wherein components in the system are connected through FPGA logic, and the system comprises the following components: a first high-speed digital-to-analog converter, an electro-optical modulator, a WGM optical microcavity, a photodiode, an analog-to-digital converter, a PID servo module, a second high-speed digital-to-analog converter and a channel control end. The components are used to process a modulation signal, and finally output a corresponding analog signal in combination with a local oscillator signal. Finally, the analog signal is used for feedback to automatically adjust the frequency and phase of the laser and the optical characteristics of the WGM optical microcavity. Through the application, the defects of the prior art, such as poor anti-interference ability of a single-mode system and an analog system, inability to achieve optimal locking effect, realization of stable control of the system and inability to be configured online, are overcome, and the application in the narrow linewidth laser system in unmanned narrow linewidth laser systems such as deep space, deep diving and deep earth is limited.

Description

Technical Field

[0001] This invention relates to the field of laser optics technology, and in particular to a miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA. Background Technology

[0002] In the field of laser frequency stabilization, traditional narrow-linewidth laser noise suppression based on external cavities and active electrical feedback relies on the performance of the optical phase-locked loop (PLL) hardware system. Its system bandwidth directly determines the high-frequency noise suppression capability of the light source. For example, traditional analog-circuit-based optical PLLs have achieved servo performance with 10MHz open-loop bandwidth and MHz-level closed-loop bandwidth.

[0003] However, single-mode systems and analog systems have poor anti-interference capabilities, cannot achieve optimal locking effects or stable system control, and cannot be configured online, which limits their application in unattended narrow-linewidth laser systems in deep space, deep diving, and deep earth environments. Summary of the Invention

[0004] This invention provides a miniaturized narrow-linewidth laser optical multimodal locking system based on an optical microcavity FPGA, which overcomes the shortcomings of existing single-mode systems and analog systems, such as poor anti-interference capabilities, inability to achieve optimal locking effect and stable system control, and inability to be configured online, thus limiting their application in unattended narrow-linewidth laser systems in deep space, deep diving, and deep earth environments.

[0005] This invention provides a miniaturized narrow-linewidth laser optical multimodal locking system using an optical microcavity FPGA. The components in the system are interconnected via FPGA logic. The system includes the following components: a first high-speed digital-to-analog converter, an electro-optic modulator, a WGM optical microcavity, a photodiode, an analog-to-digital converter, a PID servo module, a second high-speed digital-to-analog converter, and a path control terminal.

[0006] The first high-speed digital-to-analog converter outputs a modulation signal to the electro-optic modulator;

[0007] The electro-optic modulator performs phase modulation on the modulation signal and then inputs it into the WGM optical microcavity;

[0008] The WGM optical microcavity performs resonant scattering processing on the phase-modulated signal and outputs the corresponding transmission signal.

[0009] The photodiode is used to amplify the transmitted signal and input the amplified transmitted signal into the analog-to-digital converter for digital signal processing to obtain the corresponding error signal.

[0010] The PID servo module calculates the first control quantity that the system needs to adjust based on the error signal, and inputs the first control quantity to the second high-speed digital-to-analog converter.

[0011] The second high-speed digital-to-analog converter outputs the first control quantity as a first analog signal and inputs the first analog signal to the path control terminal. The first analog signal includes a first analog current signal and a first analog voltage signal.

[0012] The path control terminal includes a laser current control terminal and a piezoelectric ceramic control terminal set in the system. The laser current control terminal is used to adjust the frequency and phase of the laser according to the first analog current signal, and the piezoelectric ceramic control terminal is used to adjust its own voltage according to the first analog voltage signal to adjust the optical characteristics of the WGM optical microcavity in order to lock the system.

[0013] Furthermore, the first high-speed digital-to-analog converter is configured with initialized output parameters, the electro-optic modulator is configured with initialized modulation parameters, the analog-to-digital converter is configured with initialized sampling parameters, and the PID servo module is configured with initialized operating parameters.

[0014] The output parameters are used to output the modulated signal;

[0015] The modulation parameters perform phase modulation on the modulation signal;

[0016] The sampling parameters are used for digital signal processing of the transmitted signal;

[0017] The operating parameters are used to calculate the control quantity based on the error signal.

[0018] Furthermore, the analog-to-digital converter is equipped with a signal processing program, and the digital signal processing procedure of the analog-to-digital converter includes:

[0019] The transmitted signal is converted to obtain the corresponding digital signal;

[0020] The signal processing program is invoked to perform frequency mixing processing on the digital signal and the local oscillator signal of the laser, and the mixed signal is then filtered to generate an error signal.

[0021] Furthermore, the FPGA is used to measure the closed-loop transfer function after the system is locked, and to call the deployed AI model based on the closed-loop transfer function, thereby adjusting the microcavity parameters of the WGM optical microcavity through the AI ​​model.

[0022] In some embodiments, the system components further include a temperature sensor, and the pathway control terminal further includes a temperature control terminal configured in the system;

[0023] The temperature sensor is used to monitor the temperature signal of the WGM optical microcavity in real time, and inputs the temperature signal after analog-to-digital conversion and the error signal together into the PID servo module to calculate the second control quantity that the system needs to adjust.

[0024] The second high-speed digital-to-analog converter outputs the second control quantity as a second analog signal, and inputs the second analog signal to the laser current control terminal and the temperature control terminal, wherein the second analog signal includes a second analog current signal and a second analog voltage signal;

[0025] The laser current control terminal is used to adjust the frequency and phase of the laser according to the second analog current signal, and the temperature control terminal is used to adjust the temperature of the WGM optical microcavity according to the second analog voltage signal, so as to lock the system.

[0026] In some embodiments, the system components further include piezoelectric sensors;

[0027] The piezoelectric sensor is used to monitor the piezoelectric signal of the piezoelectric ceramic control terminal in real time, and inputs the piezoelectric signal after analog-to-digital conversion, together with the error signal and the temperature signal, into the PID servo module to calculate the third control variable that the system needs to adjust.

[0028] The second high-speed digital-to-analog converter outputs the third control quantity as a third analog signal, and inputs the third analog signal to the laser current control terminal, the temperature control terminal, and the piezoelectric ceramic control terminal, wherein the analog signal includes a third analog current signal and a third analog voltage signal;

[0029] The laser current control terminal is used to adjust the frequency and phase of the laser according to the third analog current signal, the temperature control terminal is used to adjust the temperature of the WGM optical microcavity according to the third analog voltage signal, and the piezoelectric ceramic control terminal is used to adjust its own voltage according to the third analog voltage signal to adjust the optical characteristics of the WGM optical microcavity in order to lock the system.

[0030] In some embodiments, the system includes two parallel subsystems, each of which includes the same components and configuration parameters as the system. The components in each subsystem are connected via FPGA logic. The configuration parameters include: the output parameters of the first high-speed digital-to-analog converter, the modulation parameters of the electro-optic modulator, the sampling parameters of the analog-to-digital converter, and the operating parameters of the PID servo module.

[0031] Furthermore, each of the subsystems performs signal processing on the modulation signal output by its respective first high-speed digital-to-analog converter, and outputs a corresponding third analog signal through its respective second high-speed digital-to-analog converter. The third analog signal is then input to its respective channel control terminal to lock each of the subsystems.

[0032] The signal processing procedures of the two subsystems are the same and independent of each other.

[0033] Furthermore, after each subsystem is locked, the closed-loop transfer function is measured through the FPGA of each subsystem, and the deployed AI model is called based on the closed-loop transfer function. The microcavity parameters of the respective WGM optical microcavity are adjusted through the AI ​​model.

[0034] Furthermore, the system also includes a difference frequency generation module, which receives the laser frequencies output by the two subsystems respectively, subtracts the two laser frequencies to generate the difference frequency corresponding to the laser, and uses the difference frequency to perform narrow beam locking on the system. The laser frequency is the frequency of the laser after the laser current control terminal in each subsystem has adjusted the frequency and phase.

[0035] This invention provides a miniaturized, narrow-linewidth laser optical multimodal locking system using an optical microcavity FPGA. The system processes the modulation signal through various components and combines it with the laser's local oscillator signal to ultimately output a corresponding analog signal. This analog signal is then used for feedback to automatically adjust the laser's frequency and phase, providing high-bandwidth feedback that helps suppress phase noise and narrow the linewidth. Furthermore, it automatically adjusts the optical characteristics of the WGM optical microcavity to achieve optimal locking performance, realizing automatic and stable system control unaffected by external factors and meeting the application requirements under various unattended conditions. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced one by one below. Obviously, the accompanying drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is one of the structural schematic diagrams of the miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA provided by the present invention.

[0038] Figure 2 This is the second schematic diagram of the structure of the miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA provided by the present invention.

[0039] Figure 3 This is the third schematic diagram of the structure of the miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA provided by the present invention.

[0040] Figure 4 This is the fourth schematic diagram of the structure of the miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA provided by the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] The present invention, a miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA (hereinafter referred to as the System), is described below with reference to the accompanying drawings.

[0043] like Figure 1 As shown, the various components in the system are logically connected via a Field Programmable Gate Array (FPGA). The system includes the following components: a first high-speed digital-to-analog converter (DAC), an electro-optic modulator (EOM), a Whispering Gallery Mode (WGM) optical microcavity, a photodiode, an analog-to-digital converter (ADC), a proportional-integral-derivative (PID) servo module, a second high-speed digital-to-analog converter (multi-channel DAC), and a path control terminal.

[0044] In this system, all the aforementioned components can be flexibly configured online according to actual application requirements, unaffected by external factors. It is also suitable for unattended, narrow-linewidth laser system scenarios such as deep space, deep-sea submersibles, and deep-earth applications.

[0045] Among the components of the system described above, some have signal processing capabilities. Before signal processing, these components with signal processing capabilities need to be initialized. Specifically, the first high-speed digital-to-analog converter is initialized with output parameters, the electro-optic modulator is initialized with modulation parameters, the analog-to-digital converter is initialized with sampling parameters, and the PID servo module is initialized with operating parameters. The output parameters are used to output the modulated signal; the modulation parameters perform phase modulation on the modulated signal; the sampling parameters are used to perform digital signal processing on the transmitted signal; and the operating parameters are used to calculate the control quantity based on the error signal.

[0046] It should be noted that these parameters are set based on theoretical analysis of the system and preliminary experimental results to ensure that the system is in a reasonable working state when it starts up.

[0047] In the system, the first high-speed digital-to-analog converter outputs a modulation signal to the electro-optic modulator. This first high-speed digital-to-analog converter is single-channel and, according to the set output parameters and a preset digital signal output mode, can output a compliant analog modulation signal to the electro-optic modulator. This modulation signal is a type of optical field with specific frequency and phase characteristics, enabling precise control of the electro-optic modulator's phase modulation degree on the input optical field.

[0048] The electro-optic modulator performs phase modulation on the modulation signal before inputting it into the WGM optical microcavity. Within the electro-optic modulator, the input light field is accurately phase-modulated according to the set modulation parameters. The phase-modulated light field is then input into the WGM optical microcavity.

[0049] The WGM (Wavelength Generated Mullion) optical microcavity performs resonant scattering on the phase-modulated signal and outputs a corresponding transmitted signal. When the modulated light field is input into the WGM optical microcavity, it alters the microcavity's geometry and optical properties, causing resonance and scattering processes within the microcavity and outputting a corresponding transmitted signal to the photodiode. The transmitted signal contains information such as the frequency and phase of the light field after its interaction with the microcavity.

[0050] Photodiodes are used to amplify transmitted signals, improving both signal strength and quality. The amplified transmitted signal is then input to an analog-to-digital converter for digital signal processing to obtain the corresponding error signal.

[0051] Here, the circuit module of the analog-to-digital converter (ADC) contains a signal processing program. The digital signal processing process of the ADC includes: first, converting the transmitted signal to obtain the corresponding digital signal; then, calling the signal processing program to perform frequency mixing on the digital signal and the local oscillator signal of the laser according to preset sampling parameters, and finally filtering the mixed signal to generate an error signal. This error signal reflects the deviation between the actual optical field frequency domain and the target frequency. Based on this deviation, the system can be adjusted to reduce the deviation and achieve system locking.

[0052] The error signal output by the analog-to-digital converter is input into the PID servo module. The PID servo module calculates the first control quantity that the system needs to adjust based on the error signal and inputs the first control quantity into the second high-speed digital-to-analog converter.

[0053] Here, the PID servo module combines preset operating parameters with the magnitude and trend of the error signal to calculate the control quantity that the system needs to adjust. The first control quantity is essentially a digital control signal used to instruct the system to perform the adjustment operation. Inputting the first control quantity to the second high-speed digital-to-analog converter is to convert this digital control signal into an analog signal to perform the adjustment operation.

[0054] The second high-speed digital-to-analog converter outputs the first control quantity as a first analog signal and inputs the first analog signal to the channel control terminal. The first analog signal includes a first analog current signal and a first analog voltage signal.

[0055] Here, the second high-speed digital-to-analog converter is multi-channel, and the number of channels can be set to two according to the actual path requirements. Here, two loops are set up: a current feedback loop and a piezoelectric ceramic control terminal (PZT) feedback loop. The output analog signal can be input to the corresponding path control terminal of each loop. The path control terminal can also be set to multiple channels according to the actual path requirements of the system, corresponding to each loop.

[0056] In this embodiment of the invention, the path control terminal includes a laser current control terminal and a piezoelectric ceramic control terminal, which correspond to the current feedback loop and the piezoelectric ceramic control terminal (PZT) feedback loop, respectively. In the current feedback loop, the laser current control terminal is used to adjust the frequency and phase of the laser according to the first analog current signal. The laser current control terminal can change its own current according to the first analog current signal to adjust the frequency and phase of the emitted laser, providing high-bandwidth feedback, suppressing phase noise, and narrowing the linewidth.

[0057] In the piezoelectric ceramic control feedback loop, the piezoelectric ceramic control terminal is used to adjust its own voltage according to the first analog voltage signal to adjust the optical characteristics of the WGM optical microcavity in order to lock the system.

[0058] The piezoelectric ceramic control terminal is in direct contact with the WGM optical microcavity. By changing the geometry and optical characteristics of the WGM optical microcavity through its own voltage, the WGM optical microcavity can output a transmission signal with a wider frequency range for the phase-modulated signal. This allows the system to lock within a wider frequency range, improving the system's locking effect.

[0059] Furthermore, within the system, since the various components are interconnected via FPGA logic, during the locking process, the FPGA is equipped with various preset algorithms and logic processing programs. These programs can monitor and assist in the signal processing and transmission of each component in real time, optimizing the control of the entire system. After successful system locking, the FPGA is used to measure the closed-loop transfer function and, based on the closed-loop transfer function, invoke the deployed AI model. The AI ​​model then adjusts the microcavity parameters of the WGM optical microcavity, thereby finding the optimal short-term and long-term stable values ​​within the system. This allows for the exploration of the system's optimal locking performance limits, laying the foundation for future expansion into more pathway systems and meeting the rapid feedback control requirements of microcavity oscillators with multi-mode feedback conditions.

[0060] Furthermore, in order to achieve locking effects in multiple modalities, such as Figure 2 As shown, this embodiment of the invention also includes a temperature sensor in the system components. The temperature sensor is logically connected to the WGM optical microcavity and the PID servo module via an FPGA, which enables the processing of optical and temperature signals, thereby performing system locking under multiple modes.

[0061] When a temperature sensor is set in the system, a temperature feedback loop channel also needs to be set in the system's locked feedback regulation process. Therefore, the channel control terminal also includes the temperature control terminal set in the system.

[0062] During system locking, the optical signal processing remains unchanged. Some components in the system are initialized first. For example, the output parameters of the first high-speed digital-to-analog converter are initialized, the modulation parameters of the electro-optic modulator are initialized, the sampling parameters of the analog-to-digital converter are initialized, and the operating parameters of the PID servo module are initialized to ensure that the system is in a reasonable working state when it starts up.

[0063] After the component parameters are initialized, the first high-speed digital-to-analog converter outputs a modulation signal to the electro-optic modulator. The electro-optic modulator performs phase modulation on the modulation signal and then inputs it into the WGM optical microcavity. The WGM optical microcavity performs resonant scattering processing on the phase-modulated modulation signal and outputs the corresponding transmission signal. The photodiode is used to amplify the transmission signal and inputs the amplified transmission signal into the analog-to-digital converter for digital signal processing to obtain the corresponding error signal.

[0064] The system incorporates a temperature sensor, necessitating temperature signal processing. The temperature sensor monitors the temperature signal of the WGM optical microcavity in real time, then performs analog-to-digital conversion on the temperature signal. This converted temperature signal, along with an error signal, is input to the PID servo module to calculate the second control variable that the system needs to adjust.

[0065] Similarly, the number of channels for the second high-speed digital-to-analog converter in the system can be set to two according to actual path requirements, here set as a current feedback loop and a temperature feedback loop respectively. The second high-speed digital-to-analog converter outputs the second control quantity as a second analog signal, which includes a second analog current signal and a second analog voltage signal. Then, the second analog signal is input to the laser current control terminal and the temperature control terminal.

[0066] In the current feedback loop, the laser current control terminal adjusts the laser frequency and phase based on the second analog current signal, providing high-bandwidth feedback, suppressing phase noise, and narrowing the linewidth. In the temperature feedback loop, the temperature control terminal adjusts the temperature of the WGM optical microcavity based on the second analog voltage signal. The temperature control terminal is in direct contact with the WGM microcavity or through radiation, convection, or other means to indirectly control the temperature of the WGM optical microcavity. Thus, by changing the temperature of the WGM optical microcavity, its optical characteristics are adjusted to lock the system, improving system stability and locking effectiveness.

[0067] After successful system locking, the FPGA is used to measure the closed-loop transfer function and call the deployed AI model based on the closed-loop transfer function. The AI ​​model is used to adjust the microcavity parameters of the WGM optical microcavity, thereby finding the optimal values ​​for short-term and long-term stability in the system, exploring the limit performance of the system's optimal locking, and laying the foundation for future expansion into more path systems to meet the fast feedback control requirements of microcavity oscillators with multi-mode feedback conditions.

[0068] In some embodiments, the system aims to achieve a locking effect under the combined action of multiple modalities, such as Figure 3As shown, in this embodiment of the invention, based on the temperature sensor described above, a piezoelectric sensor is set in the system. The piezoelectric sensor is logically connected to the piezoelectric ceramic control terminal and the PID servo module through the FPGA to simultaneously process the optical signal, temperature signal and piezoelectric signal, thereby realizing system locking under the combined action of multiple modes.

[0069] When a piezoelectric sensor is installed in the system, a piezoelectric feedback loop channel also needs to be set up during the system's locked feedback regulation process. Therefore, in addition to the laser current control terminal and temperature control terminal set in the system, the path control terminal also includes a piezoelectric ceramic control terminal set in the system.

[0070] Of course, during the system locking process, the optical signal processing process remains unchanged. It still involves initializing some components in the system first. For example, the output parameters of the first high-speed digital-to-analog converter are set, the modulation parameters of the electro-optic modulator are set, the sampling parameters of the analog-to-digital converter are set, and the operating parameters of the PID servo module are set to ensure that the system is in a reasonable working state when it starts up.

[0071] After the component parameters are initialized, the first high-speed digital-to-analog converter outputs a modulation signal to the electro-optic modulator. The electro-optic modulator performs phase modulation on the modulation signal and then inputs it into the WGM optical microcavity. The WGM optical microcavity performs resonant scattering processing on the phase-modulated modulation signal and outputs the corresponding transmission signal. The photodiode is used to amplify the transmission signal and inputs the amplified transmission signal into the analog-to-digital converter for digital signal processing to obtain the corresponding error signal.

[0072] A temperature sensor is installed in the system, requiring corresponding temperature signal processing. The temperature sensor is used to monitor the temperature signal of the WGM optical microcavity in real time, and then the temperature signal is converted from analog to digital.

[0073] The system also includes a piezoelectric sensor, which necessitates piezoelectric signal processing. The piezoelectric sensor monitors the physical properties of the piezoelectric ceramic at the control terminal, allowing for real-time monitoring of the piezoelectric signal. This signal is then converted from analog to digital.

[0074] Finally, the temperature signal, piezoelectric signal, and error signal after analog-to-digital conversion are input together into the PID servo module to calculate the third control variable that the system needs to adjust.

[0075] Similarly, the second high-speed digital-to-analog converter in the system can be configured with three channels depending on the actual path requirements. Here, these are configured as a current feedback loop, a temperature feedback loop, and a piezoelectric ceramic control terminal feedback loop, respectively. The second high-speed digital-to-analog converter outputs the third control quantity as a third analog signal, which includes a third analog current signal and a third analog voltage signal. This third analog signal is then input to the laser current control terminal, temperature control terminal, and piezoelectric ceramic control terminal.

[0076] In the current feedback loop, the laser current control terminal adjusts the laser frequency and phase based on the third analog current signal, providing high-bandwidth feedback, suppressing phase noise, and narrowing the linewidth. In the temperature feedback loop, the temperature control terminal adjusts the temperature of the WGM optical microcavity based on the third analog voltage signal. The temperature control terminal is in direct contact with the WGM microcavity or through radiation, convection, etc., to indirectly control the temperature of the WGM optical microcavity, thus adjusting its optical characteristics by changing its temperature. In the piezoelectric ceramic control terminal feedback loop, the piezoelectric ceramic control terminal adjusts its own voltage based on the third analog voltage signal to adjust the optical characteristics of the WGM optical microcavity for system locking. The piezoelectric ceramic control terminal is in direct contact with the WGM optical microcavity, changing its geometry and optical characteristics through its own voltage, thus improving system stability and locking effect.

[0077] After successful system locking, the FPGA is also used to measure the closed-loop transfer function after system locking, and calls the deployed AI model based on the closed-loop transfer function. The AI ​​model is used to adjust the microcavity parameters of the WGM optical microcavity, thereby finding the optimal values ​​for short-term and long-term stability in the system, exploring the limit performance of the system's optimal locking, and laying the foundation for future expansion to more path systems to meet the fast feedback control requirements of microcavity oscillators with multi-mode feedback conditions.

[0078] In some embodiments, the optical microcavity FPGA miniaturized narrow linewidth laser optical multimodal locking system can also achieve dual-channel operation, with multimodal system locking implemented in each channel.

[0079] like Figure 4As shown, specifically, the miniaturized narrow-linewidth laser optical multimodal locking system using an optical microcavity FPGA includes two parallel subsystems. The components and configuration parameters of each subsystem are the same as those of the original system. The components in each subsystem are connected by FPGA logic. The configuration parameters include: the output parameters of the first high-speed digital-to-analog converter, the modulation parameters of the electro-optic modulator, the sampling parameters of the analog-to-digital converter, and the operating parameters of the PID servo module. In other words, the parameter initialization settings of the two subsystems are also the same. Each subsystem is the same as the original system and can achieve system locking under the combined action of multiple modes, that is, system feedback adjustment is performed through optical signals, temperature signals, and piezoelectric signals.

[0080] This can be understood as deploying a miniaturized narrow-linewidth laser optical multimodal locking system using an optical microcavity FPGA as two subsystems, or as deploying two miniaturized narrow-linewidth laser optical multimodal locking systems using an optical microcavity FPGA. The following explanation uses the deployment as two subsystems.

[0081] like Figure 4 As shown, the two subsystems operate in parallel, with their signal processing processes being independent and non-interfering with each other. The components and configuration parameters included in each subsystem are the same as those in the miniaturized narrow-linewidth laser optical multimodal locking system using optical microcavity FPGA, and the components within each subsystem are still connected via FPGA logic.

[0082] Of course, the signal processing procedures of the two subsystems are the same and independent of each other. That is, each subsystem processes the modulation signal output by its own first high-speed digital-to-analog converter, and outputs the corresponding third analog signal through its own second high-speed digital-to-analog converter. The third analog signal is then input to its respective channel control terminal to lock each subsystem.

[0083] Specifically, the first high-speed digital-to-analog converters of the two subsystems output modulation signals to their respective electro-optic modulators according to preset output parameters. The electro-optic modulators perform phase modulation on the input modulation signals. The modulated signals are then input to their respective WGM optical microcavities, where complex optical interactions occur, generating transmission signals containing optical field information. These transmission signals are received by their respective photodiodes and amplified to improve signal strength and quality. They are then input to their respective analog-to-digital converters for digital signal processing to generate error signals.

[0084] Here, the analog-to-digital converters of the two subsystems convert the amplified transmitted signal into a digital signal, which is then mixed and filtered with their respective local oscillator signals. Precise mixing and filtering of the two signals generates a corresponding error signal. This error signal accurately reflects the deviation between the optical field frequency and the target frequency.

[0085] Temperature sensors are installed in both subsystems to monitor the temperature signal of their respective WGM optical microcavities in real time. The monitored temperature signals are converted from analog to digital and then input together with the error signals generated by the respective optical signal processing into their respective PID servo modules for comprehensive processing.

[0086] Piezoelectric sensors are also installed in both subsystems to monitor the physical characteristics of the piezoelectric ceramics at their respective control terminals in real time. The monitored piezoelectric signals are converted from analog to digital and then fed into their respective PID servo modules along with their respective error and temperature signals for comprehensive processing.

[0087] Similarly, the second high-speed digital-to-analog converter in each subsystem is configured with three channels based on actual path requirements: a current feedback loop, a temperature feedback loop, and a piezoelectric ceramic control terminal feedback loop. The second high-speed digital-to-analog converter outputs the third control quantity as a third analog signal, which includes both a third analog current signal and a third analog voltage signal. This third analog signal is then input to the respective laser current control terminal, temperature control terminal, and piezoelectric ceramic control terminal to achieve locking within their respective subsystems. The feedback and locking process will not be elaborated here.

[0088] After each subsystem is successfully locked, the closed-loop transfer function is measured through the FPGA of each subsystem, and the deployed AI model is called based on the closed-loop transfer function. The AI ​​model is used to adjust the microcavity parameters of each WGM optical microcavity. In this way, the optimal values ​​of short-term stability and long-term stability in each subsystem can be found, and the limit performance of the system's optimal locking can be explored. This lays the foundation for future expansion to more path systems, so as to meet the fast feedback control requirements of microcavity oscillators with multi-mode feedback conditions.

[0089] like Figure 4 As shown, based on the dual-channel architecture, this embodiment of the invention further includes a difference frequency generation module in the miniaturized narrow-linewidth laser optical multimodal locking system using an optical microcavity FPGA. This difference frequency generation module is logically connected to both subsystems via the FPGA. The module receives the laser frequencies output by the two subsystems, which are the frequencies of the lasers after the laser current control terminals in each subsystem have adjusted frequency and phase. Then, the two laser frequencies are subtracted to generate the difference frequency, which is used for narrow-beam locking of the system. This further enhances the narrow-beam locking effect of the two subsystems.

[0090] The miniaturized narrow-linewidth laser optical multimodal locking system provided by this invention, based on an FPGA, automatically adjusts the laser frequency and phase, providing high-bandwidth feedback, which helps suppress phase noise and narrow the linewidth. It also automatically adjusts the optical characteristics of the WGM optical microcavity in the system to achieve optimal locking performance. System locking is achieved under the combined action of signals in multiple modes and multimodal signals, unaffected by external factors, and can meet the application requirements under various unattended conditions. After system locking, the closed-loop transfer function is measured via FPGA, and based on the closed-loop transfer function, a deployed AI model is invoked. The AI ​​model adjusts the microcavity parameters of the WGM optical microcavity, thereby finding the optimal short-term and long-term stable values ​​in the system, exploring the limits of the system's optimal locking performance, and laying the foundation for future expansion into more pathway systems to meet the rapid feedback control requirements of microcavity oscillators with multimodal feedback conditions.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGAs, characterized in that, The components in the system are interconnected via FPGA logic. The system includes the following components: a first high-speed digital-to-analog converter, an electro-optic modulator, a WGM optical microcavity, a photodiode, an analog-to-digital converter, a PID servo module, a second high-speed digital-to-analog converter, and a path control terminal. The first high-speed digital-to-analog converter outputs a modulation signal to the electro-optic modulator; The electro-optic modulator performs phase modulation on the modulation signal and then inputs it into the WGM optical microcavity; The WGM optical microcavity performs resonant scattering processing on the phase-modulated signal and outputs the corresponding transmission signal. The photodiode is used to amplify the transmitted signal and input the amplified transmitted signal into the analog-to-digital converter for digital signal processing to obtain the corresponding error signal. The PID servo module calculates the first control quantity that the system needs to adjust based on the error signal, and inputs the first control quantity to the second high-speed digital-to-analog converter. The second high-speed digital-to-analog converter outputs the first control quantity as a first analog signal and inputs the first analog signal to the path control terminal. The first analog signal includes a first analog current signal and a first analog voltage signal. The path control terminal includes a laser current control terminal and a piezoelectric ceramic control terminal set in the system. The laser current control terminal is used to adjust the frequency and phase of the laser according to the first analog current signal, and the piezoelectric ceramic control terminal is used to adjust its own voltage according to the first analog voltage signal to adjust the optical characteristics of the WGM optical microcavity in order to lock the system.

2. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGAs according to claim 1, characterized in that, The first high-speed digital-to-analog converter is set with initialized output parameters, the electro-optic modulator is set with initialized modulation parameters, the analog-to-digital converter is set with initialized sampling parameters, and the PID servo module is set with initialized operating parameters. The output parameters are used to output the modulated signal; The modulation parameters perform phase modulation on the modulation signal; The sampling parameters are used for digital signal processing of the transmitted signal; The operating parameters are used to calculate the control quantity based on the error signal.

3. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGAs according to claim 1, characterized in that, The analog-to-digital converter (ADC) is equipped with a signal processing program, and the digital signal processing procedure of the ADC includes: The transmitted signal is converted to obtain the corresponding digital signal; The signal processing program is invoked to perform frequency mixing processing on the digital signal and the local oscillator signal of the laser, and the mixed signal is then filtered to generate an error signal.

4. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGAs according to claim 1, characterized in that, The FPGA is used to measure the closed-loop transfer function after the system is locked, and to call the deployed AI model based on the closed-loop transfer function, thereby adjusting the microcavity parameters of the WGM optical microcavity through the AI ​​model.

5. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGAs according to claim 1, characterized in that, The system also includes a temperature sensor, and the pathway control terminal also includes a temperature control terminal set by the system. The temperature sensor is used to monitor the temperature signal of the WGM optical microcavity in real time, and inputs the temperature signal after analog-to-digital conversion and the error signal together into the PID servo module to calculate the second control quantity that the system needs to adjust. The second high-speed digital-to-analog converter outputs the second control quantity as a second analog signal, and inputs the second analog signal to the laser current control terminal and the temperature control terminal, wherein the second analog signal includes a second analog current signal and a second analog voltage signal; The laser current control terminal is used to adjust the frequency and phase of the laser according to the second analog current signal, and the temperature control terminal is used to adjust the temperature of the WGM optical microcavity according to the second analog voltage signal, so as to lock the system.

6. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGAs according to claim 5, characterized in that, The system also includes piezoelectric sensors; The piezoelectric sensor is used to monitor the piezoelectric signal of the piezoelectric ceramic control terminal in real time, and inputs the piezoelectric signal after analog-to-digital conversion, together with the error signal and the temperature signal, into the PID servo module to calculate the third control variable that the system needs to adjust. The second high-speed digital-to-analog converter outputs the third control quantity as a third analog signal, and inputs the third analog signal to the laser current control terminal, the temperature control terminal, and the piezoelectric ceramic control terminal, wherein the analog signal includes a third analog current signal and a third analog voltage signal; The laser current control terminal is used to adjust the frequency and phase of the laser according to the third analog current signal, the temperature control terminal is used to adjust the temperature of the WGM optical microcavity according to the third analog voltage signal, and the piezoelectric ceramic control terminal is used to adjust its own voltage according to the third analog voltage signal to adjust the optical characteristics of the WGM optical microcavity in order to lock the system.

7. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA according to claim 6, characterized in that, The system includes two parallel subsystems. Each subsystem includes the same components and configuration parameters as the main system. The components in each subsystem are connected by FPGA logic. The configuration parameters include: the output parameters of the first high-speed digital-to-analog converter, the modulation parameters of the electro-optic modulator, the sampling parameters of the analog-to-digital converter, and the operating parameters of the PID servo module.

8. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA according to claim 7, characterized in that, Each of the subsystems processes the modulation signal output by its respective first high-speed digital-to-analog converter, outputs a corresponding third analog signal through its respective second high-speed digital-to-analog converter, and inputs the third analog signal to its respective channel control terminal to lock each of the subsystems. The signal processing procedures of the two subsystems are the same and independent of each other.

9. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGAs according to claim 8, characterized in that, After each subsystem is locked, the closed-loop transfer function is measured through the FPGA of each subsystem, and the deployed AI model is called based on the closed-loop transfer function. The microcavity parameters of the respective WGM optical microcavity are adjusted through the AI ​​model.

10. The miniaturized narrow-linewidth laser optical multimodal locking system for optical microcavity FPGA according to claim 7, characterized in that, The system also includes a difference frequency generation module, which receives the laser frequencies output by the two subsystems respectively, subtracts the two laser frequencies to generate the difference frequency corresponding to the laser, and uses the difference frequency to perform narrow beam locking on the system. The laser frequency is the frequency of the laser after the laser current control terminal in each subsystem has adjusted the frequency and phase.

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