Semiconductor laser frequency locking system based on on-chip mode-locked laser and locking method thereof
Patent Information
- Application Number
- CN202611339872.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-01
- Publication Date
- 2026-11-03
AI Technical Summary
Existing semiconductor lasers are severely affected by external factors, exhibiting spontaneous emission phase noise and frequency drift issues, which cannot meet the requirements of high-precision optical measurement and quantum manipulation. Furthermore, existing on-chip optical comb solutions do not achieve high-precision self-locking of the optical comb repetition frequency and carrier envelope offset frequency, and thermal crosstalk affects frequency locking accuracy.
The semiconductor laser frequency locking system employing an on-chip mode-locked laser includes an on-chip mode-locked laser module, a semiconductor laser output module, an on-chip optical coupling beat frequency module, a dual-loop frequency locking servo module, and a thermal management decoupling module. Frequency synchronization locking is achieved through an optical comb self-locking loop and a semiconductor laser frequency locking loop, and thermal crosstalk is compensated in real time through the thermal management module.
It achieves the narrowing of semiconductor laser linewidth from MHz to Hz, improves frequency stability by 3-4 orders of magnitude per second, miniaturizes the system, reduces power consumption, and is compatible with airborne, spaceborne and portable precision optical equipment, with long-term frequency drift below 0.1Hz.
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Figure CN123034208A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of laser frequency stabilization technology, integrated photonics and optical comb precision calibration technology, and specifically to a semiconductor laser frequency locking system and locking method based on an on-chip mode-locked laser. Background Technology
[0002] Semiconductor lasers possess significant advantages such as small size, low cost, high electro-optical conversion efficiency, and good wavelength tunability, making them core light source devices in fields such as optical communication, lidar, precision spectral detection, and quantum precision sensing. However, semiconductor lasers in free-running conditions are highly susceptible to external factors such as drive current noise, ambient temperature fluctuations, mechanical vibration, and air disturbances, resulting in severe spontaneous emission phase noise. Conventional DFB and DBR type semiconductor lasers typically have output linewidths in the MHz range, and their frequency stability over one second is only... The frequency drift problem is prominent, which cannot meet the core requirements of high-end applications such as high-precision optical measurement, quantum manipulation, and optical frequency standard construction for narrow linewidth and ultra-high frequency stability of light sources.
[0003] Currently, the mainstream semiconductor laser linewidth narrowing and frequency stabilization solutions in the industry are mainly divided into three categories: The first category is external cavity feedback frequency stabilization technology, which constructs external cavity resonance through discrete external optical structures such as gratings and FP resonant cavities to achieve laser linewidth compression, which can narrow the laser linewidth to 10~100 kHz. However, this solution relies on discrete optical components, resulting in a large system size, weak anti-vibration interference capability, and inability to effectively suppress long-term temperature drift, thus limiting the improvement in frequency stability. The second category is ultra-stable cavity PDH locking technology, which locks the semiconductor laser to a high-precision ultra-stable cavity, achieving Hz-level linewidth output. However, the ultra-stable cavity has extremely high manufacturing costs and stringent requirements for installation environment, vibration conditions, and temperature stability, making it difficult to achieve miniaturization and engineering integration deployment. The third category is traditional desktop fiber comb frequency locking technology, which uses a large femtosecond fiber comb as the frequency reference to lock the semiconductor laser, achieving ultra-high stability output. However, the overall equipment size is large, power consumption is high, and the system architecture is complex, making it unsuitable for chip-based and miniaturized application scenarios.
[0004] In recent years, integrated photonics technology has rapidly iterated, achieving technological breakthroughs and initial industrialization of on-chip mode-locked lasers (on-chip optical combs) based on low-loss materials such as silicon nitride and lithium niobate. These combs possess advantages such as high repetition rate, low transmission loss, chip-level integration, and strong anti-interference capabilities, completely breaking the size and power consumption constraints of traditional desktop optical combs. However, existing on-chip optical comb application solutions still have significant technical shortcomings: firstly, the repetition rate of the optical comb has not been achieved. With carrier envelope offset frequency The dual-parameter high-precision self-locking has poor frequency stability of the optical comb teeth themselves, making it unsuitable as an absolute optical frequency reference. Secondly, no dedicated compensation mechanism is designed for the optoelectronic thermal coupling characteristics of the on-chip photonic chip. Thermal crosstalk and thermal drift during chip operation will cause optical comb frequency shift, significantly reducing laser frequency locking accuracy. Thirdly, there is a lack of a dedicated semiconductor laser frequency locking architecture adapted to the characteristics of the on-chip optical comb, making it impossible to achieve high-precision, fully chip-based semiconductor laser frequency stabilization.
[0005] In summary, existing semiconductor laser frequency stabilization technologies generally suffer from drawbacks such as low integration, limited frequency locking accuracy, poor thermal interference suppression, and difficulty in miniaturization deployment. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a semiconductor laser frequency locking system with high stability and low thermal drift.
[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a semiconductor laser frequency locking system based on an on-chip mode-locked laser, characterized in that it includes: an on-chip mode-locked laser module, a semiconductor laser output module, an on-chip optical coupling beat frequency module, a dual-loop frequency locking servo module, and a thermal management decoupling module; The on-chip mode-locked laser module is used to output a stable optical comb, which satisfies the frequency domain calculation formula: ,in, The frequency of the comb teeth. The number of the comb teeth. The frequency of optical comb repetition. The carrier envelope offset frequency; The semiconductor laser output module is used to output continuous narrowband semiconductor laser as a working light source to be frequency locked. The on-chip optical coupling beat frequency module is optically coupled and connected to the on-chip mode-locked laser module, and is used to combine and mix the semiconductor laser with a single tooth of the optical comb to generate a stable heterodyne beat frequency signal. The dual-loop frequency-locking servo module is electrically connected to the on-chip mode-locked laser module, the on-chip optical coupling beat frequency module, and the semiconductor laser output module, respectively. The dual-loop frequency-locking servo module includes a self-locking loop for the optical comb and a frequency-locking loop for the semiconductor laser that work together. The self-locking loop for the optical comb is used to lock the repetition frequency of the optical comb. and carrier envelope offset frequency An absolute optical frequency reference is constructed; the semiconductor laser frequency-locking loop is used to correct the output frequency of the semiconductor laser in real time based on the heterodyne beat frequency signal. The thermal management decoupling module is integrated on the surface of the photonic chip and is used to collect the global temperature signal of the photonic chip in real time. This is used to control and compensate for the frequency shift of the optical comb and the laser frequency drift caused by thermal crosstalk of the chip, so as to ensure the long-term stable frequency output of the system.
[0008] As a preferred embodiment, the optical comb self-locking loop includes a radio frequency reference source, a first FPGA servo controller, and a cavity length tuning drive unit; The radio frequency reference source is an OCXO (Oven-Switch Oscillator) or a rubidium atomic clock, used to output a 10 MHz standard radio frequency reference signal; the first FPGA servo controller acquires the optical comb repetition frequency signal and the carrier envelope offset frequency signal respectively, and corrects the optical path of the mode-locked micro-ring resonator through thermal tuning or electro-optic tuning to realize the repetition frequency of the optical comb. Carrier envelope offset frequency Dual-parameter synchronous high-precision locking.
[0009] As a preferred embodiment, the semiconductor laser frequency-locking loop includes a second FPGA servo controller and a laser drive adjustment unit; The laser drive adjustment unit integrates a high-frequency current modulation module, a precision temperature control module, and an external cavity PZT tuning module. The current modulation bandwidth of the high-frequency current modulation module is not less than 1 MHz. Through multi-bandwidth coordinated control, it simultaneously suppresses the high-frequency phase noise and low-frequency temperature drift noise of semiconductor laser.
[0010] As a preferred embodiment, the on-chip mode-locked laser module includes an on-chip pump source, a gain waveguide, a mode-locked micro-ring resonator, a dispersion compensation unit, and an on-chip f-2f self-referenced nonlinear waveguide, all integrated on a low-loss photonic chip made of silicon nitride or lithium niobate.
[0011] As a preferred embodiment, the optical comb repetition frequency of the on-chip mode-locked laser module is 10 GHz / 100 GHz, the initial linewidth of a single comb tooth is no greater than 1 kHz, and the optical operating band covers 400 nm-2000 nm.
[0012] As a preferred embodiment, the on-chip optical coupling beat frequency module integrates an on-chip beam splitter, a polarization adaptive controller, a passive optical mixer, and a high-speed photodetector. The high-speed photodetector has a working bandwidth of no less than 10 GHz and generates a heterodyne beat frequency signal with a signal-to-noise ratio of no less than 25 dB, so as to accurately extract the frequency difference signal between the semiconductor laser and the optical comb teeth, providing a basis for closed-loop frequency locking.
[0013] As a preferred embodiment, the thermal management decoupling module includes a distributed temperature sensor, an array of micro-heating electrodes, and a thermal crosstalk compensation algorithm unit. The distributed temperature sensor is used to collect the global temperature of the photonic chip in real time, achieving a chip temperature control accuracy of ±0.01℃. The thermal crosstalk compensation algorithm unit corrects the optical comb locking parameters in real time using a pre-calibrated thermal crosstalk coefficient, eliminating the repetition frequency of the optical comb. With carrier envelope offset frequency Thermal coupling interference between them.
[0014] Another technical problem to be solved by the present invention is to provide a locking method for the above-mentioned semiconductor laser frequency locking system.
[0015] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a semiconductor laser frequency locking method based on an on-chip mode-locked laser, comprising the following steps: S1. System initialization and preheating: After the device is powered on, the parameters are initialized and the preheating is stable. Then, the on-chip mode-locked laser module is started, and the pump power of the on-chip pump source and the phase parameters of the mode-locked micro-ring resonator are adjusted to output a stable optical comb. S2, Optical Comb Self-Reference Dual-Parameter Locking: The first FPGA servo controller acquires the repetition frequency of the optical comb. By comparing the optical comb with a standard signal from an RF reference source, the repetition frequency of the optical comb is locked through cavity length tuning. The on-chip f-2f nonlinear waveguide is used to perform self-referenced frequency doubling and beat frequency extraction to extract the carrier envelope offset frequency. By adjusting the pump power, the carrier envelope offset frequency is locked. Complete the absolute calibration of the optical frequency scale; S3. High-precision heterodyne beat frequency signal generation: The semiconductor laser output module outputs continuous laser, which is split into a fixed ratio reference light by the on-chip beam splitter of the on-chip optical coupling beat frequency module. After the reference light is polarized and calibrated by the polarization adaptive controller, it is passively mixed with a single comb tooth of the optical comb through a passive optical mixer to generate a stable heterodyne beat frequency signal with a high signal-to-noise ratio. S4. Semiconductor laser closed-loop precise frequency locking: The second FPGA servo controller collects the beat frequency signal in real time, compares it with the preset standard RF frequency and calculates the frequency error signal. The laser drive adjustment unit adjusts the driving current, working temperature and external cavity length of the semiconductor laser through multi-bandwidth collaborative adjustment to fix the beat frequency difference and realize the closed-loop locking of the semiconductor laser frequency. S5. Dynamic thermal crosstalk compensation and frequency stabilization: The thermal management decoupling module monitors the temperature changes across the entire photonic chip in real time and dynamically corrects the repetition frequency of the optical comb based on a pre-calibrated thermal interference model. Carrier envelope offset frequency Dual-parameter and semiconductor laser driving parameters are used to suppress long-term frequency drift of the system in real time.
[0016] As a preferred embodiment, in step S2, after locking is completed, the optical comb repetition frequency is... The steady-state drift is no greater than 1 Hz, and the carrier envelope offset frequency is... The linewidth is no greater than 100 Hz.
[0017] As a preferred embodiment, in step S4, after frequency locking is completed, the output linewidth of the semiconductor laser is no greater than 10 Hz, and the frequency stability over 1 second is better than [previous specification]. The frequency drift during long-term continuous operation is no greater than .
[0018] The beneficial effects of this invention are: 1. Excellent linewidth narrowing effect and extremely high frequency stability. This invention uses a self-locking calibrated on-chip optical comb as the absolute frequency reference, which can compress the MHz-level free-running linewidth of semiconductor lasers to the Hz or even mHz level, achieving a frequency stability of up to 1 second. The stability is improved by 3 to 4 orders of magnitude compared to traditional external cavity feedback and ordinary microcavity frequency stabilization solutions, reaching the technical level of desktop high-precision optical comb frequency locking.
[0019] 2. Fully integrated on a single chip, enabling miniaturized and low-power deployment. The core optical path, signal detection, servo control, and thermal management units of this invention are all integrated on a single photonic chip, eliminating traditional discrete optical components. The overall system size is reduced by more than 90%, and the power consumption of the whole machine is significantly reduced. This breaks away from the limitation of traditional high-precision frequency locking equipment being only deployable on a desktop, and can be adapted to miniaturized application scenarios such as airborne, spaceborne, and portable precision optical equipment.
[0020] 3. Dual-loop collaborative locking, balancing frequency locking accuracy and system robustness. This invention employs a dual-loop architecture of optical comb self-locking and semiconductor laser frequency locking. It first calibrates the frequency reference and then locks onto the target light source, eliminating frequency locking errors caused by reference drift at the source. Simultaneously, by coordinating the control of laser current, temperature, and external cavity length across multiple bandwidths, it synchronously achieves high-frequency phase noise suppression and low-frequency temperature drift compensation, significantly improving frequency locking stability and anti-interference capabilities.
[0021] 4. Dedicated thermal crosstalk compensation ensures outstanding long-term stability. This invention addresses the inherent thermal coupling defects of on-chip optoelectronic devices by designing a global real-time thermal management and dynamic algorithm compensation mechanism. This maintains chip temperature control accuracy within ±0.01℃, effectively eliminating... and Thermal crosstalk interference, long-term system frequency drift is lower than It can achieve continuous and stable operation 24 hours a day.
[0022] 5. High versatility and wide applicability. This invention is compatible with various semiconductor lasers across the entire wavelength range of 400 nm to 2000 nm. No changes to the core system architecture are required; adaptation can be achieved simply by fine-tuning the optical comb band parameters. It can be widely applied in high-precision fields such as high-end optical communication, quantum sensing, precision spectral detection, lidar, and optical atomic clocks. Attached Figure Description
[0023] Figure 1 is a schematic diagram of the overall system architecture of the present invention.
[0024] Figure 2 is a schematic diagram of the dual-parameter self-locking loop principle of the on-chip optical comb of the present invention.
[0025] Figure 3 is a schematic diagram of the semiconductor laser heterodyne beat frequency and closed-loop frequency locking principle of the present invention.
[0026] Figure 4 is a schematic diagram of the working process of the thermal management decoupling module of the present invention.
[0027] Explanation of reference numerals in the attached figures: 1-On-chip mode-locked laser module, 2-Semiconductor laser output module, 3-On-chip optical coupling beat frequency module, 4-Dual-loop frequency-locked servo module, 5-Thermal management decoupling module, 6-RF reference source, 7-First FPGA servo controller, 8-Second FPGA servo controller, 9-High-speed photodetector. Detailed Implementation
[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0029] As shown in Figures 1-4, this embodiment provides a semiconductor laser frequency locking system based on an on-chip mode-locked laser, adapted to 1550 nm fiber optic communication and precision spectral scenarios. The core parameters and structural configuration are as follows: On-chip mode-locked laser module 1 uses silicon nitride ( The low-loss photonic chip fabrication, with a chip size of 20mm×15mm, integrates a 1550 nm on-chip pumped DFB light source, a high nonlinear gain waveguide, a 40 GHz mode-locked micro-ring resonator, a dispersion compensation unit, and an f-2f self-referenced nonlinear waveguide; the output optical comb has a repetition frequency of 40 GHz, an initial linewidth of 800 Hz per comb tooth, and a working band covering 1500 nm~1600 nm, meeting the precision frequency locking requirements of the communication band.
[0030] Semiconductor laser output module 2 uses a commercially available 1550 nm conventional DFB semiconductor laser with a free-running linewidth of 2 MHz and a rated output power of 10 mW. It supports high-precision current modulation and precise temperature control tuning, and is suitable for the multi-bandwidth frequency locking control requirements of this system.
[0031] The on-chip optical coupling beat frequency module 3 integrates an on-chip beam splitter with a splitting ratio of 1:9, a polarization adaptive controller, a passive optical mixer, and a 20 GHz high-speed photodetector 9. It can automatically complete polarization matching and optical path coupling, and the final generated beat frequency signal has a signal-to-noise ratio of up to 30 dB, which meets the requirements for high-precision frequency identification and closed-loop frequency locking.
[0032] The dual-loop frequency-locked servo module 4 is equipped with a high-precision rubidium atomic clock as the RF reference source 6, and features a first FPGA servo controller 7 and a second FPGA servo controller 8; the first FPGA servo controller 7 is responsible for the optical comb. , Dual-parameter self-locking, the second FPGA servo controller 8 is responsible for the closed-loop frequency control of the semiconductor laser; the laser drive adjustment unit supports 1 MHz bandwidth high-frequency current modulation, 1 kHz bandwidth precision temperature control adjustment and 100 kHz bandwidth external cavity PZT tuning, to achieve full coverage suppression of multi-band noise.
[0033] The thermal management decoupling module 5 integrates 6 distributed thin-film temperature sensors and arrayed micro heating electrodes, enabling real-time monitoring of the entire temperature range of the photonic chip and precise temperature control in micro-areas, with a temperature control accuracy of ±0.01℃. It also features a built-in proprietary thermal crosstalk compensation algorithm that can correct various frequency deviations caused by thermal drift in real time.
[0034] The high-precision frequency locking method for the semiconductor laser frequency locking system based on an on-chip mode-locked laser described above has the following specific operation steps: S1. The system is powered on and initialized, and preheated for 30 minutes to ensure that the optical path, circuit and temperature of the equipment are completely stable. Then, the on-chip mode-locked laser module 1 is started, the pump power of the on-chip pump source is adjusted to 200 mW, the phase parameters of the mode-locked micro-ring resonator are finely adjusted, and the system enters a stable passive mode-locked working state, continuously outputting a 40 GHz high repetition frequency optical comb.
[0035] S2. Perform optical comb self-reference dual-parameter locking: The first FPGA servo controller extracts the repetition frequency of the optical comb. By precisely comparing the optical frequency with the 10 MHz standard reference signal of a rubidium atomic clock, and finely adjusting the optical path of the micro-ring resonant cavity through micro-heating electrodes, the repetition frequency of the optical comb is adjusted. Precisely locked at 40 GHz, with steady-state drift ≤0.5 Hz; utilizes on-chip f-2f nonlinear waveguides to achieve frequency doubling and self-reference beat frequency, accurately extracting the carrier envelope offset frequency. Feedback adjustment of the on-chip pump light source power shifts the carrier envelope frequency. Stable locked at 10 MHz, carrier envelope offset frequency after locking With a linewidth ≤ 50 Hz, absolute calibration of the optical frequency scale is achieved.
[0036] S3. Generating a high-precision heterodyne beat frequency signal: The semiconductor laser output module 2 outputs continuous laser light, which is split into 10% reference light by the on-chip beam splitter of the on-chip optical coupling beat frequency module, and the remaining 90% of the laser light is used as the effective working output light. After the reference light completes adaptive polarization matching by the polarization adaptive controller, it is passively mixed with the 1550.123 nm comb teeth of the on-chip optical comb by the passive optical mixer. The signal is detected by the 20 GHz high-speed photodetector to generate a stable 100 MHz heterodyne beat frequency signal.
[0037] S4. Precise frequency locking in semiconductor laser closed loop: The second FPGA servo controller acquires the beat frequency signal in real time at high speed and compares it with the preset 100 MHz standard RF signal in real time to accurately calculate the instantaneous frequency error; adopting a multi-bandwidth collaborative control strategy, it suppresses high-frequency phase noise of the laser through high-frequency current modulation, compensates for low-frequency temperature drift error through precise temperature control, and corrects residual frequency deviation by finely adjusting the length of the external cavity PZT, so that the beat frequency signal is always stably locked at 100 MHz, achieving long-term closed-loop stability of semiconductor laser frequency.
[0038] S5. Dynamic thermal crosstalk compensation and frequency stabilization: The thermal management decoupling module collects real-time temperature data of the photonic chip across its entire range and dynamically corrects the optical comb based on a pre-calibrated thermal interference coefficient model. Carrier envelope offset frequency Locking parameters and semiconductor laser drive operating parameters to counteract thermal crosstalk and thermal drift generated during chip operation in real time, ensuring continuous steady-state operation of the system 24 hours a day. Implementation effect
[0039] After frequency locking is completed in this embodiment, the output linewidth of the semiconductor laser is compressed to 2 Hz, and the frequency stability reaches 1 second. Continuous 24-hour uninterrupted operation frequency drift ≤ During operation, there are no abnormal phenomena such as frequency jumps or linewidth broadening. The system has excellent resistance to vibration and environmental temperature disturbances. Compared with traditional discrete frequency stabilization solutions, the integration level is improved by more than 90%, and the frequency stability is improved by 3 to 4 orders of magnitude, which fully meets the usage requirements of high-precision application scenarios such as precision spectral detection, quantum sensing, and high-end coherent optical communication.
[0040] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some examples of its application, and are not intended to limit the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention.
Claims
1. A semiconductor laser frequency locking system based on an on-chip mode-locked laser, comprising: The system comprises an on-chip mode-locked laser module, a semiconductor laser output module, an on-chip optical coupling beat frequency module, a dual-loop frequency-locked servo module, and a thermal management decoupling module; characterized in that... The on-chip mode-locked laser module is used to output a stable optical comb, which satisfies the frequency domain calculation formula: ,in, The frequency of the comb teeth. The number of the comb teeth. The frequency of optical comb repetition. The carrier envelope offset frequency; The semiconductor laser output module is used to output continuous narrowband semiconductor laser as a working light source to be frequency locked. The on-chip optical coupling beat frequency module is optically coupled and connected to the on-chip mode-locked laser module, and is used to combine and mix the semiconductor laser with a single tooth of the optical comb to generate a stable heterodyne beat frequency signal. The dual-loop frequency-locking servo module is electrically connected to the on-chip mode-locked laser module, the on-chip optical coupling beat frequency module, and the semiconductor laser output module, respectively. The dual-loop frequency-locking servo module includes a self-locking loop for the optical comb and a frequency-locking loop for the semiconductor laser that work together. The self-locking loop for the optical comb is used to lock the repetition frequency of the optical comb. and carrier envelope offset frequency An absolute optical frequency reference is constructed; the semiconductor laser frequency-locking loop is used to correct the output frequency of the semiconductor laser in real time based on the heterodyne beat frequency signal. The thermal management decoupling module is integrated on the surface of the photonic chip and is used to collect the global temperature signal of the photonic chip in real time. This is used to control and compensate for the frequency shift of the optical comb and the laser frequency drift caused by thermal crosstalk of the chip, so as to ensure the long-term stable frequency output of the system.
2. The semiconductor laser frequency locking system based on an on-chip mode-locked laser according to claim 1, characterized in that, The optical comb self-locking loop includes a radio frequency reference source, a first FPGA servo controller, and a cavity length tuning drive unit; The radio frequency reference source is an OCXO (Oven-Switch Oscillator) or a rubidium atomic clock, used to output a 10 MHz standard radio frequency reference signal; the first FPGA servo controller acquires the optical comb repetition frequency signal and the carrier envelope offset frequency signal respectively, and corrects the optical path of the mode-locked micro-ring resonator through thermal tuning or electro-optic tuning to realize the repetition frequency of the optical comb. Carrier envelope offset frequency Dual-parameter synchronous high-precision locking.
3. The semiconductor laser frequency locking system based on an on-chip mode-locked laser according to claim 1, characterized in that, The semiconductor laser frequency-locking loop includes a second FPGA servo controller and a laser drive adjustment unit; The laser drive adjustment unit integrates a high-frequency current modulation module, a precision temperature control module, and an external cavity PZT tuning module. The current modulation bandwidth of the high-frequency current modulation module is not less than 1 MHz. Through multi-bandwidth coordinated control, it simultaneously suppresses the high-frequency phase noise and low-frequency temperature drift noise of semiconductor laser.
4. The semiconductor laser frequency locking system based on an on-chip mode-locked laser according to claim 1, characterized in that, The on-chip mode-locked laser module includes an on-chip pump source, gain waveguide, mode-locked micro-ring resonator, dispersion compensation unit, and on-chip f-2f self-referenced nonlinear waveguide, all integrated on a low-loss photonic chip made of silicon nitride or lithium niobate.
5. The semiconductor laser frequency locking system based on an on-chip mode-locked laser according to claim 1, characterized in that, The optical comb of the on-chip mode-locked laser module has a repetition frequency of 10 GHz / 100 GHz, an initial linewidth of no more than 1 kHz for a single comb tooth, and an optical operating band covering 400 nm-2000 nm.
6. The semiconductor laser frequency locking system based on an on-chip mode-locked laser according to claim 1, characterized in that, The on-chip optical coupling beat frequency module integrates an on-chip beam splitter, a polarization adaptive controller, a passive optical mixer, and a high-speed photodetector. The high-speed photodetector has a working bandwidth of no less than 10 GHz and generates a heterodyne beat frequency signal with a signal-to-noise ratio of no less than 25 dB, so as to accurately extract the frequency difference signal between the semiconductor laser and the optical comb teeth, providing a basis for closed-loop frequency locking.
7. The semiconductor laser frequency locking system based on an on-chip mode-locked laser according to claim 1, characterized in that, The thermal management decoupling module includes a distributed temperature sensor, an array of micro-heating electrodes, and a thermal crosstalk compensation algorithm unit. The distributed temperature sensor is used to collect the global temperature of the photonic chip in real time, achieving a chip temperature control accuracy of ±0.01℃. The thermal crosstalk compensation algorithm unit corrects the optical comb locking parameters in real time using a pre-calibrated thermal crosstalk coefficient, eliminating the repetition frequency of the optical comb. With carrier envelope offset frequency Thermal coupling interference between them.
8. A semiconductor laser frequency locking method based on an on-chip mode-locked laser, characterized in that, The frequency locking system according to any one of claims 1-7 comprises the following steps: S1. System initialization and preheating: After the device is powered on, the parameters are initialized and the preheating is stable. Then, the on-chip mode-locked laser module is started, and the pump power of the on-chip pump source and the phase parameters of the mode-locked micro-ring resonator are adjusted to output a stable optical comb. S2. Optical Comb Self-Reference Dual-Parameter Locking: The first FPGA servo controller acquires the repetition frequency of the optical comb. By comparing the optical comb with a standard signal from an RF reference source, the repetition frequency of the optical comb is locked through cavity length tuning. The on-chip f-2f nonlinear waveguide is used to perform self-referenced frequency doubling and beat frequency extraction to extract the carrier envelope offset frequency. By adjusting the pump power, the carrier envelope offset frequency is locked. Complete the absolute calibration of the optical frequency scale; S3. High-precision heterodyne beat frequency signal generation: The semiconductor laser output module outputs continuous laser, which is split into a fixed ratio reference light by the on-chip beam splitter of the on-chip optical coupling beat frequency module. After the reference light is polarized and calibrated by the polarization adaptive controller, it is passively mixed with a single comb tooth of the optical comb through a passive optical mixer to generate a stable heterodyne beat frequency signal with a high signal-to-noise ratio. S4. Semiconductor laser closed-loop precise frequency locking: The second FPGA servo controller collects the beat frequency signal in real time, compares it with the preset standard RF frequency and calculates the frequency error signal. The laser drive adjustment unit adjusts the driving current, working temperature and external cavity length of the semiconductor laser through multi-bandwidth collaborative adjustment to fix the beat frequency difference and realize the closed-loop locking of the semiconductor laser frequency. S5. Dynamic thermal crosstalk compensation and frequency stabilization: The thermal management decoupling module monitors the temperature changes across the entire photonic chip in real time and dynamically corrects the repetition frequency of the optical comb based on a pre-calibrated thermal interference model. Carrier envelope offset frequency Dual-parameter and semiconductor laser driving parameters are used to suppress long-term frequency drift of the system in real time.
9. The semiconductor laser frequency locking method based on an on-chip mode-locked laser according to claim 8, characterized in that, In step S2, after locking is completed, the optical comb repetition frequency is... The steady-state drift is no greater than 1 Hz, and the carrier envelope offset frequency is... The linewidth is no greater than 100 Hz.
10. The semiconductor laser frequency locking method based on an on-chip mode-locked laser according to claim 8, characterized in that, In step S4, after frequency locking is completed, the output linewidth of the semiconductor laser is no greater than 10 Hz, and the frequency stability for 1 second is better than... The frequency drift during long-term continuous operation is no greater than .