Optical microcavity FPGA (Field Programmable Gate Array) miniaturized narrow-linewidth laser optical multi-mode locking system

Abstract

The invention provides an optical microcavity FPGA (Field Programmable Gate Array) miniaturized narrow linewidth laser optical multi-mode locking system, all parts in the system are logically connected through an FPGA, and the system comprises the following parts: 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 (Proportion Integration Differentiation) servo module, a second high-speed digital-to-analog converter and an access control end. Modulation signals are processed through all the components, and corresponding analog signals are finally output in combination with local oscillator signals. Finally, an 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. According to the application, the defects that a single-mode system and a simulation system in the prior art are poor in anti-interference capability, cannot achieve an optimal locking effect, cannot realize stable control of the system, cannot be configured online, and are limited to be applied to unattended narrow linewidth laser systems such as deep space, deep diving and deep ground are overcome.

Description

Technical Field

[0001] The invention relates to the field of laser optics technology, and in particular to an optical microcavity FPGA miniaturized narrow-linewidth laser optics multi-mode locking system. Background Art

[0002] In the field of laser frequency stabilization, traditional narrow-linewidth laser noise suppression based on external cavity and active electrical feedback depends on the performance of the optical phase-locked loop hardware system. Its system bandwidth directly determines the ability of the light source to suppress high-frequency noise. For example, the traditional optical phase-locked loop based on analog circuits has achieved servo performance of 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 the optimal locking effect, realize stable system control, and cannot be configured online, which limits their application in unmanned narrow-linewidth laser systems in deep space, deep diving, deep earth, etc. Summary of the invention

[0004] The present invention provides an optical microcavity FPGA miniaturized narrow-linewidth laser optical multi-mode locking system, which is used to overcome the defects of the single-mode system and the analog system in the prior art, such as poor anti-interference ability, inability to achieve the optimal locking effect, realize system stable control, and inability to be configured online, which limits the application in unmanned narrow-linewidth laser systems in deep space, deep diving, deep ground, etc.

[0005] The present invention provides an optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system, wherein the 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 path control terminal; The first high-speed digital-to-analog converter outputs a modulation signal to the electro-optical modulator; The electro-optic modulator performs phase modulation on the modulation signal and then inputs the phase modulation signal into the WGM optical microcavity; The WGM optical microcavity performs resonance scattering processing on the phase modulated modulation signal and outputs a corresponding transmission signal; The photodiode is used to perform signal amplification processing on the transmission signal, and input the transmission signal after signal amplification processing into the analog-to-digital converter for digital signal processing to obtain a corresponding error signal; The PID servo module calculates a first control variable that needs to be adjusted for the system according to the error signal, and inputs the first control variable into the second high-speed digital-to-analog converter; The second high-speed digital-to-analog converter outputs the first control amount as a first analog signal, and inputs the first analog signal to the path control terminal, wherein the first analog signal includes a first analog current signal and a first analog voltage signal; The channel control end includes a laser current control end and a piezoelectric ceramic control end provided in the system. The laser current control end is used to adjust the frequency and phase of the laser according to the first analog current signal. The piezoelectric ceramic control end is used to adjust its own voltage according to the first analog voltage signal to adjust the optical properties of the WGM optical microcavity so as to lock the system.

[0006] Further, the first high-speed digital-to-analog converter is provided with initialized output parameters, the electro-optical modulator is provided with initialized modulation parameters, the analog-to-digital converter is provided with initialized sampling parameters, and the PID servo module is provided with initialized working parameters; The output parameters are used to output a modulated signal; The modulation parameter performs phase modulation on the modulation signal; The sampling parameters are used to perform digital signal processing on the transmission signal; The operating parameters are used to calculate the control amount according to the error signal.

[0007] Furthermore, a signal processing program is deployed in the analog-to-digital converter, and the digital signal processing process of the analog-to-digital converter includes: Performing signal conversion on the transmission signal to obtain a corresponding digital signal; The signal processing program is called to perform mixing processing on the digital signal and the local oscillator signal of the laser, and the mixed signal is filtered to generate an error signal.

[0008] Furthermore, the FPGA is used to measure a closed-loop transfer function after the system is locked, and to call a deployed AI model based on the closed-loop transfer function, and to adjust the microcavity parameters of the WGM optical microcavity through the AI ​​model.

[0009] In some embodiments, the components of the system further include a temperature sensor, and the passage control terminal further includes a temperature control terminal provided by the system; The temperature sensor is used to monitor the temperature signal of the WGM optical microcavity in real time, and input the temperature signal after analog-to-digital conversion and the error signal into the PID servo module to calculate the second control amount that needs to be adjusted by the system; The second high-speed digital-to-analog converter outputs the second control amount 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 to lock the system.

[0010] In some embodiments, the components of the system further include a piezoelectric sensor; The piezoelectric sensor is used to monitor the piezoelectric signal of the piezoelectric ceramic control end in real time, and input 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 amount that needs to be adjusted by the system; The second high-speed digital-to-analog converter outputs the third control amount as a third analog signal, and inputs the third analog signal to the laser current control end, the temperature control end and the piezoelectric ceramic control end, wherein the analog signal includes a third analog current signal and a third analog voltage signal; The laser current control end is used to adjust the frequency and phase of the laser according to the third analog current signal, the temperature control end is used to adjust the temperature of the WGM optical microcavity according to the third analog voltage signal, and the piezoelectric ceramic control end is used to adjust its own voltage according to the third analog voltage signal to adjust the optical properties of the WGM optical microcavity to lock the system.

[0011] In some embodiments, the system includes two parallel subsystems, each of the subsystems includes the same components and configuration parameters as the system, and the components in each subsystem are connected through FPGA logic. The configuration parameters include: output parameters of the first high-speed digital-to-analog converter, modulation parameters of the electro-optical modulator, sampling parameters of the analog-to-digital converter, and operating parameters of the PID servo module.

[0012] Furthermore, each of the subsystems performs signal processing on the modulation signal output by the respective first high-speed digital-to-analog converter, outputs a corresponding third analog signal through the respective second high-speed digital-to-analog converter, and inputs the third analog signal to the respective channel control terminal, so as to lock each of the subsystems; The signal processing processes of the two subsystems are identical and independent of each other.

[0013] Furthermore, after each of the subsystems is locked, the closed-loop transfer function is measured by the FPGA of each of the subsystems, and the deployed AI model is called based on the respective closed-loop transfer function, and the microcavity parameters of the respective WGM optical microcavity are adjusted by the AI ​​model.

[0014] Furthermore, the components of the system are also provided with a difference frequency generation module, which is used to receive the laser frequencies respectively output by the two subsystems, and subtract the two laser frequencies to generate a difference frequency corresponding to the laser, and the difference frequency is used to perform narrow light locking on the system. The laser frequency is the frequency of the laser after the frequency and phase are adjusted at the laser current control end in each of the subsystems.

[0015] The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-modal locking system provided by the present invention processes the modulated signal by configuring various components in the system, and finally outputs the corresponding analog signal in combination with the local oscillator signal of the laser. Finally, the analog signal is used for feedback to automatically adjust the frequency and phase of the laser, providing high-bandwidth feedback, which is conducive to suppressing phase noise and narrowing the linewidth. It can also automatically adjust the optical properties of the WGM optical microcavity in the system to achieve the optimal locking effect, realize automatic and stable control of the system, and is not interfered by external factors, and can meet various application requirements under unattended conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced one by one below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is one of the structural schematic diagrams of the optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system provided by the present invention.

[0018] Figure 2 This is the second structural schematic diagram of the optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system provided by the present invention.

[0019] Figure 3 This is the third structural schematic diagram of the optical microcavity FPGA miniaturized narrow-linewidth laser optical multi-mode locking system provided by the present invention.

[0020] Figure 4 This is the fourth structural schematic diagram of the optical microcavity FPGA miniaturized narrow-linewidth laser optical multi-mode locking system provided by the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system (hereinafter referred to as the system) of the present invention is described below in conjunction with the accompanying drawings.

[0023] like Figure 1 As shown, the various components in the system are logically connected through 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 channel control terminal.

[0024] In the system, all the above components can be flexibly configured online according to actual application requirements without being interfered by external factors. For example, it can also be used in unmanned narrow-linewidth laser system scenarios such as deep space, deep diving, and deep underground.

[0025] Among the above-mentioned components of the system, some components have certain signal processing functions. Before processing the signal, these components of the system with signal processing functions need to be initialized. Specifically, the first high-speed digital-to-analog converter is provided with initialized output parameters, the electro-optical modulator is provided with initialized modulation parameters, the analog-to-digital converter is provided with initialized sampling parameters, and the PID servo module is provided with initialized working parameters, wherein the output parameters are used to output the modulation signal; the modulation parameters perform phase modulation on the modulation signal; the sampling parameters are used to perform digital signal processing on the transmission signal; and the working parameters are used to calculate the control amount according to the error signal.

[0026] It should be noted that the settings of these parameters are based on theoretical analysis of the system and preliminary experimental results to ensure that the system is in a reasonable working state when it is started.

[0027] In the system, the first high-speed digital-to-analog converter outputs a modulation signal to the electro-optical modulator. The first high-speed digital-to-analog converter is a single-channel converter, and can output a required analog modulation signal to the electro-optical modulator according to the set output parameters and the preset digital signal output mode. This modulation signal belongs to a light field, has specific frequency and phase characteristics, and can accurately control the phase modulation degree of the electro-optical modulator on the input light field.

[0028] The electro-optic modulator phase modulates the modulation signal and inputs it into the WGM optical microcavity. In the electro-optic modulator, the input light field is accurately phase modulated according to the set modulation parameters. The phase-modulated light field is input into the WGM optical microcavity.

[0029] The WGM optical microcavity performs resonant scattering on the phase-modulated modulation signal and outputs the corresponding transmission signal. After the modulated light field is input into the WGM optical microcavity, the geometric dimensions and optical properties of the base WGM optical microcavity will be changed, so that physical processes such as resonance and scattering will occur in the WGM optical microcavity, and the corresponding transmission signal will be output to the photodiode. The transmission signal contains information such as frequency and phase after the interaction between the light field and the microcavity.

[0030] The photodiode is used to amplify the transmission signal, which can improve the strength and quality of the signal. The transmission signal after signal amplification is then input into an analog-to-digital converter for digital signal processing to obtain a corresponding error signal.

[0031] Here, the circuit module in the analog-to-digital converter is deployed with a signal processing program. The digital signal processing process of the analog-to-digital converter includes: first converting the transmission signal to obtain the corresponding digital signal; then calling the signal processing program to mix the digital signal and the local oscillator signal of the laser according to the preset sampling parameters, and filtering the mixed signal to generate an error signal. This error signal reflects the deviation between the actual light field frequency domain and the target frequency. Based on this deviation, the system can be feedback-adjusted to reduce the deviation and complete the locking of the system.

[0032] 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 amount that the system needs to adjust according to the error signal, and inputs the first control amount into the second high-speed digital-to-analog converter.

[0033] Here, the PID servo module will combine the preset working parameters and calculate the control amount that the system needs to adjust according to the size and change trend of the error signal. The first control amount itself is essentially a digital control signal used to instruct the system to perform an adjustment operation. The first control amount is input into the second high-speed digital-to-analog converter in order to convert this digital control signal into an analog signal and perform an adjustment operation.

[0034] The second high-speed digital-to-analog converter outputs the first control amount 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.

[0035] 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 channel requirements. Here, two loops, a current feedback loop and a piezoelectric ceramic control end (PZT) feedback loop, are set respectively, and the output analog signal can be input into the channel control end corresponding to each loop. The channel control end can also be set to multiple channels according to the actual channel requirements of the system, corresponding to each loop.

[0036] In the embodiment of the present invention, the channel control end includes a laser current control end and a piezoelectric ceramic control end set by the system, which correspond to the current feedback loop and the piezoelectric ceramic control end (PZT) feedback loop respectively. In the current feedback loop, the laser current control end is used to adjust the frequency and phase of the laser according to the first analog current signal. The laser current control end can change its own current according to the first analog current signal to adjust the frequency and phase of the emitted laser, provide high-bandwidth feedback, suppress phase noise and narrow the line width.

[0037] In the piezoelectric ceramic control end feedback loop, the piezoelectric ceramic control end is used to adjust its own voltage according to the first analog voltage signal to adjust the optical properties of the WGM optical microcavity to lock the system.

[0038] The piezoelectric ceramic control end is in direct contact with the WGM optical microcavity, and changes the geometric dimensions and optical properties of the WGM optical microcavity through its own voltage. By adjusting the optical properties of the WGM optical microcavity, the WGM optical microcavity can output a transmission signal with a larger frequency range for the modulated signal after phase modulation, so that the system can be locked within a larger frequency range, thereby improving the locking effect of the system.

[0039] In addition, in the system, since the components are connected through FPGA logic, during the locking process, various preset algorithms and logic processing programs are deployed in the FPGA, which can monitor and help process the signal processing and signal transmission of each component in real time, and optimize the control of the entire system. After the system is successfully locked, the FPGA is used to measure the closed-loop transfer function after the system is locked, and call the deployed AI model based on the closed-loop transfer function. The microcavity parameters of the WGM optical microcavity are adjusted through the AI ​​model, thereby finding the optimal values ​​of short-term stability and long-term stability in the system, exploring the ultimate performance of the system's optimal locking, and laying the foundation for future expansion to more channel systems to meet the rapid feedback control requirements of microcavity oscillators with multi-mode feedback conditions.

[0040] Furthermore, in order to achieve the locking effect in multiple modes, such as Figure 2 As shown, in the embodiment of the present invention, a temperature sensor is also provided in the components of the system. The temperature sensor is logically connected with the WGM optical microcavity and the PID servo module respectively by using FPGA, so as to realize the processing of the optical signal and the temperature signal, thereby performing system locking in multiple modes.

[0041] When a temperature sensor is provided in the system, accordingly, a channel of a temperature feedback loop also needs to be provided in the feedback adjustment process of the system lock, so the channel control end also includes a temperature control end provided by the system.

[0042] During the system locking process, the optical signal processing process remains unchanged, and some components in the system are still initialized first. For example, the initialized output parameters are set in the first high-speed digital-to-analog converter, the initialized modulation parameters are set in the electro-optical modulator, the initialized sampling parameters are set in the analog-to-digital converter, and the initialized working parameters are set in the PID servo module to ensure that the system is in a reasonable working state when it starts.

[0043] After the parameter initialization of the component is completed, the first high-speed digital-to-analog converter still outputs the modulation signal to the electro-optical modulator, and the electro-optical modulator phase-modulates the modulation signal and 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 the transmission signal after the signal amplification is input into the analog-to-digital converter for digital signal processing to obtain the corresponding error signal.

[0044] A temperature sensor is set in the system, and the temperature signal processing process needs to be performed accordingly. 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 into an analog-to-digital format, and the temperature signal after the analog-to-digital conversion is input into the PID servo module together with the error signal to calculate the second control quantity that the system needs to adjust.

[0045] Similarly, the number of paths of the second high-speed digital-to-analog converter in the system can be set to two according to actual path requirements, which are respectively set as a current feedback loop and a temperature feedback loop. The second high-speed digital-to-analog converter outputs the second control quantity as a second analog signal, and the second analog signal 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.

[0046] In the current feedback loop, the laser current control end is used to adjust the frequency and phase of the laser according to the second analog current signal, provide high-bandwidth feedback, suppress phase noise and narrow the line width. In the temperature feedback loop, the temperature control end is used to adjust the temperature of the WGM optical microcavity according to the second analog voltage signal. The temperature control end is in direct contact with the WGM microcavity or through radiation, convection, etc., to achieve indirect control of the temperature of the WGM optical microcavity. In this way, the optical properties of the WGM optical microcavity are adjusted by changing the temperature of the WGM optical microcavity to lock the system and improve the stability and locking effect of the system.

[0047] After the system is successfully locked, the FPGA is used to measure the closed-loop transfer function after the system is locked, and call the deployed AI model based on the closed-loop transfer function. The microcavity parameters of the WGM optical microcavity are adjusted through the AI ​​model, thereby finding the optimal values ​​of short-term stability and long-term stability in the system, and exploring the ultimate performance of the system's optimal locking, laying the foundation for future expansion into more channel systems to meet the needs of fast feedback control of microcavity oscillators with multi-mode feedback conditions.

[0048] In some embodiments, the system is used to achieve a locking effect under the joint action of multiple modes, such as Figure 3 As shown, in the embodiment of the present invention, based on the above-mentioned temperature sensor, a piezoelectric sensor is arranged in the system, and the piezoelectric sensor is logically connected to the piezoelectric ceramic control end and the PID servo module through FPGA, so as to simultaneously process the optical signal, the temperature signal and the piezoelectric signal, thereby realizing system locking under the joint action of multiple modes.

[0049] When a piezoelectric sensor is set in the system, a channel of a piezoelectric feedback loop needs to be set accordingly in the feedback adjustment process of the system lock. Therefore, the channel control end includes a piezoelectric ceramic control end set in the system on the basis of the laser current control end and the temperature control end set in the system.

[0050] Of course, during the system locking process, the optical signal processing process remains unchanged, and some components in the system are still initialized first. For example, the initialized output parameters are set in the first high-speed digital-to-analog converter, the initialized modulation parameters are set in the electro-optical modulator, the initialized sampling parameters are set in the analog-to-digital converter, and the initialized working parameters are set in the PID servo module to ensure that the system is in a reasonable working state when it starts.

[0051] After the parameter initialization of the component is completed, the first high-speed digital-to-analog converter still outputs the modulation signal to the electro-optical modulator, and the electro-optical modulator phase-modulates the modulation signal and 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 the transmission signal after the signal amplification is input into the analog-to-digital converter for digital signal processing to obtain the corresponding error signal.

[0052] A temperature sensor is set in the system, and the temperature signal processing process needs to be performed accordingly. The temperature sensor is used to monitor the temperature signal of the WGM optical microcavity in real time, and then convert the temperature signal into analog-to-digital.

[0053] The system also has a piezoelectric sensor, which needs to perform a piezoelectric signal processing process accordingly. The piezoelectric sensor is used to monitor the physical properties of the piezoelectric ceramics at the piezoelectric ceramic control end, and is used to monitor the piezoelectric signal at the piezoelectric ceramic control end in real time, and then convert the piezoelectric signal into analog-to-digital.

[0054] Finally, the temperature signal, piezoelectric signal and error signal after analog-to-digital conversion are input into the PID servo module to calculate the third control quantity that needs to be adjusted by the system.

[0055] Similarly, the number of paths of the second high-speed digital-to-analog converter in the system can be set to three according to actual path requirements, which are respectively set as a current feedback loop, a temperature feedback loop, and a piezoelectric ceramic control end feedback loop. The second high-speed digital-to-analog converter outputs the third control quantity as a third analog signal, and the third analog signal includes a third analog current signal and a third analog voltage signal. Then the third analog signal is input to the laser current control end, the temperature control end, and the piezoelectric ceramic control end.

[0056] In the current feedback loop, the laser current control end is used to adjust the frequency and phase of the laser according to the third analog current signal, provide high-bandwidth feedback, suppress phase noise and narrow the linewidth. In the temperature feedback loop, the temperature control end is used to adjust the temperature of the WGM optical microcavity according to the third analog voltage signal. The temperature control end is in direct contact with the WGM microcavity or in contact with it through radiation, convection, etc., to achieve indirect control of the temperature of the WGM optical microcavity, so as to adjust the optical properties of the WGM optical microcavity by changing the temperature of the WGM optical microcavity. In the piezoelectric ceramic control end feedback loop, the piezoelectric ceramic control end is used to adjust its own voltage according to the third analog voltage signal to adjust the optical properties of the WGM optical microcavity to lock the system. The piezoelectric ceramic control end is in direct contact with the WGM optical microcavity, and changes the geometric dimensions and optical properties of the WGM optical microcavity through its own voltage, which can improve the stability and locking effect of the system.

[0057] After the system is successfully locked, the FPGA is also used to measure the closed-loop transfer function after the system is locked, and call the deployed AI model based on the closed-loop transfer function. The microcavity parameters of the WGM optical microcavity are adjusted through the AI ​​model, thereby finding the optimal values ​​of short-term stability and long-term stability in the system, and exploring the ultimate performance of the system's optimal locking, laying the foundation for future expansion into more channel systems to meet the needs of fast feedback control of microcavity oscillators with multi-mode feedback conditions.

[0058] In some embodiments, the optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system can also realize dual-channel, and achieve system locking under multi-mode in each channel.

[0059] like Figure 4 As shown, specifically, the optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system includes two parallel subsystems, and the components and configuration parameters included in each subsystem are the same as those of the system. The components in each subsystem are connected through FPGA logic, and the configuration parameters include: the output parameters of the first high-speed digital-to-analog converter, the modulation parameters of the electro-optical modulator, the sampling parameters of the analog-to-digital converter, and the working parameters of the PID servo module, that is, the parameter initialization settings of the two subsystems are also the same, and each subsystem is the same as the original system, and can achieve system locking under the joint action of multiple modes, that is, system feedback adjustment is performed through optical signals, temperature signals and piezoelectric signals.

[0060] Here, it can be understood as deploying the optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system as two subsystems, or it can be understood as deploying two optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking systems. The following is an explanation based on the deployment as two subsystems.

[0061] like Figure 4 As shown, the two subsystems are parallel, and their signal processing processes are independent and do not interfere with each other. The components and configuration parameters included in each subsystem are the same as those of the optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system, and the components in each subsystem are still connected through FPGA logic.

[0062] Of course, the signal processing processes of the two subsystems are the same and independent of each other. That is, each subsystem processes the modulation signal output by its first high-speed digital-to-analog converter, outputs the corresponding third analog signal through its second high-speed digital-to-analog converter, and inputs the third analog signal to its channel control terminal to lock each subsystem.

[0063] Specifically, the first high-speed digital-to-analog converters of the two subsystems output modulation signals to their respective electro-optical modulators according to preset output parameters, and the electro-optical modulators perform phase modulation on the input modulation signals. The modulated modulation signals are input into their respective WGM optical microcavities, and complex optical interactions occur in the WGM optical microcavities to generate transmission signals containing light field information. The transmission signals are received by their respective photodiodes and amplified to improve the signal strength and quality, and then respectively input into their respective analog-to-digital converters for digital signal processing to generate error signals.

[0064] Here, the analog-to-digital converters of the two subsystems convert the amplified transmission signal into a digital signal, which is mixed and filtered with the respective local oscillator signals. The two signals are accurately mixed and filtered to generate a corresponding error signal. The error signal accurately reflects the deviation between the light field frequency and the target frequency.

[0065] Temperature sensors are set in both subsystems to monitor the temperature signals of their respective WGM optical microcavities in real time. After analog-to-digital conversion, the monitored temperature signals are input into their respective PID servo modules together with the error signals generated by their respective optical signal processing for comprehensive processing.

[0066] Piezoelectric sensors are also set in both subsystems to monitor the physical properties of piezoelectric ceramics at their respective piezoelectric ceramic control ends in real time. After analog-to-digital conversion, the monitored piezoelectric signals are input into their respective PID servo modules together with their respective error signals and temperature signals for comprehensive processing.

[0067] Similarly, the number of paths of the second high-speed digital-to-analog converter in each subsystem is set to three paths according to the actual path requirements, that is, it is set to a current feedback loop, a temperature feedback loop, and a piezoelectric ceramic control end feedback loop. The second high-speed digital-to-analog converter outputs the third control quantity as a third analog signal, and the third analog signal includes a third analog current signal and a third analog voltage signal. Then the third analog signal is input to the respective laser current control end, temperature control end, and piezoelectric ceramic control end to achieve the locking of the respective subsystems. The feedback and locking process will not be repeated here.

[0068] 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 respective closed-loop transfer function. The microcavity parameters of the respective WGM optical microcavity are adjusted through the AI ​​model. In this way, the optimal values ​​of short-term stability and long-term stability in each subsystem can be found respectively, and the ultimate performance of the system's optimal locking can be explored, laying the foundation for future expansion to more channel systems to meet the needs of fast feedback control of microcavity oscillators with multi-mode feedback conditions.

[0069] like Figure 4 As shown, on the basis of dual channels, the embodiment of the present invention also sets a difference frequency generation module in the optical microcavity FPGA miniaturized narrow linewidth laser optical multi-modal locking system, and the difference frequency generation module is logically connected to the two subsystems through the FPGA. The difference frequency generation module is used to receive the laser frequencies output by the two subsystems respectively, that is, the frequency of the laser after the laser current control end in each subsystem adjusts the frequency and phase. Then the two laser frequencies are subtracted to generate the difference frequency corresponding to the laser, and the difference frequency is used to perform narrow light locking on the system, that is to say, the two subsystems can be further narrow light locked, while improving the locking effect of the two subsystems.

[0070] The optical microcavity FPGA miniaturized narrow-linewidth laser optical multi-mode locking system provided by the embodiment of the present invention automatically adjusts the frequency and phase of the laser, provides high-bandwidth feedback, and is conducive to suppressing phase noise and narrowing the linewidth. It can also automatically adjust the optical properties of the WGM optical microcavity in the system to achieve the optimal locking effect. And the system locking is achieved under the joint action of signals in multiple modes and multi-modal signals, without interference from external factors, and can meet various application requirements under unattended conditions. After the system is locked, the closed-loop transfer function is measured by FPGA, and the deployed AI model is called based on the closed-loop transfer function. The microcavity parameters of the WGM optical microcavity are adjusted by the AI ​​model, thereby finding the optimal values ​​of short-term stability and long-term stability in the system, exploring the ultimate performance of the system's optimal locking, and laying the foundation for future expansion to more channel systems to meet the rapid feedback control requirements of microcavity oscillators with multi-mode feedback conditions.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system, characterized in that: The components in the system are connected through FPGA logic, and the system includes 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 terminal; The first high-speed digital-to-analog converter outputs a modulation signal to the electro-optical modulator; The electro-optic modulator performs phase modulation on the modulation signal and then inputs the phase modulation signal into the WGM optical microcavity; The WGM optical microcavity performs resonance scattering processing on the phase modulated modulation signal and outputs a corresponding transmission signal; The photodiode is used to perform signal amplification processing on the transmission signal, and input the transmission signal after signal amplification processing into the analog-to-digital converter for digital signal processing to obtain a corresponding error signal; The PID servo module calculates a first control variable that needs to be adjusted for the system according to the error signal, and inputs the first control variable into the second high-speed digital-to-analog converter; The second high-speed digital-to-analog converter outputs the first control amount as a first analog signal, and inputs the first analog signal to the path control terminal, wherein the first analog signal includes a first analog current signal and a first analog voltage signal; The channel control end includes a laser current control end and a piezoelectric ceramic control end provided in the system. The laser current control end is used to adjust the frequency and phase of the laser according to the first analog current signal. The piezoelectric ceramic control end is used to adjust its own voltage according to the first analog voltage signal to adjust the optical properties of the WGM optical microcavity so as to lock the system.

2. The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system according to claim 1, characterized in that: The first high-speed digital-to-analog converter is provided with initialized output parameters, the electro-optical modulator is provided with initialized modulation parameters, the analog-to-digital converter is provided with initialized sampling parameters, and the PID servo module is provided with initialized working parameters; The output parameters are used to output a modulated signal; The modulation parameter performs phase modulation on the modulation signal; The sampling parameters are used to perform digital signal processing on the transmission signal; The operating parameters are used to calculate the control amount according to the error signal.

3. The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system according to claim 1, characterized in that: A signal processing program is deployed in the analog-to-digital converter, and the digital signal processing process of the analog-to-digital converter includes: Performing signal conversion on the transmission signal to obtain a corresponding digital signal; The signal processing program is called to perform mixing processing on the digital signal and the local oscillator signal of the laser, and the mixed signal is filtered to generate an error signal.

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

5. The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system according to claim 1, characterized in that: The components of the system also include a temperature sensor, and the passage control end also includes a temperature control end provided by the system; The temperature sensor is used to monitor the temperature signal of the WGM optical microcavity in real time, and input the temperature signal after analog-to-digital conversion and the error signal into the PID servo module to calculate the second control amount that needs to be adjusted by the system; The second high-speed digital-to-analog converter outputs the second control amount 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 to lock the system.

6. The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system according to claim 5, characterized in that: Components of the system also include a piezoelectric sensor; The piezoelectric sensor is used to monitor the piezoelectric signal of the piezoelectric ceramic control end in real time, and input 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 amount that needs to be adjusted by the system; The second high-speed digital-to-analog converter outputs the third control amount as a third analog signal, and inputs the third analog signal to the laser current control end, the temperature control end and the piezoelectric ceramic control end, wherein the analog signal includes a third analog current signal and a third analog voltage signal; The laser current control end is used to adjust the frequency and phase of the laser according to the third analog current signal, the temperature control end is used to adjust the temperature of the WGM optical microcavity according to the third analog voltage signal, and the piezoelectric ceramic control end is used to adjust its own voltage according to the third analog voltage signal to adjust the optical properties of the WGM optical microcavity to lock the system.

7. The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system according to claim 6, characterized in that: 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 through FPGA logic. The configuration parameters include: output parameters of the first high-speed digital-to-analog converter, modulation parameters of the electro-optical modulator, sampling parameters of the analog-to-digital converter, and working parameters of the PID servo module.

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

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

10. The optical microcavity FPGA miniaturized narrow linewidth laser optical multi-mode locking system according to claim 7, characterized in that: The components of the system are also provided with a difference frequency generation module, which is used to receive the laser frequencies respectively output by the two subsystems, and subtract the two laser frequencies to generate a difference frequency corresponding to the laser. The difference frequency is used to perform narrow light locking on the system. The laser frequency is the frequency of the laser after the frequency and phase are adjusted at the laser current control end in each of the subsystems.

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