Active locking system and method for mid-infrared supercontinuum

Abstract

The application discloses a mid-infrared supercontinuum active locking system and method, and the system comprises a pump light generation module, a main light path processing module, a reference signal generation module, an optical cavity length control module and a feedback control module. The pump light generation module is used for outputting pump light and splitting the pump light into at least two paths. The main light path processing module is used for coupling the pump light in one path into an optical fiber after optical signal optimization processing to perform spectrum widening. The reference signal generation module is used for converting the pump light in another path into a reference signal. The optical cavity length control module is used for receiving the optical signal after spectrum widening and performing optical cavity length control. The reference signal generation module is used for performing multi-stage splitting on the optical signal after optical cavity length control, extracting a target split optical signal used for feedback, and converting the target split optical signal into a reference signal. The feedback control module is used for generating a correction voltage based on the reference signal and the reference signal to drive the optical cavity length control module to perform active locking of the cavity length. The problems of limited spectrum widening and low energy utilization rate are solved, and the anti-interference ability and stability of the system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mid-infrared supercontinuum, and particularly relates to a mid-infrared supercontinuum active locking system and method. BACKGROUND

[0002] Supercontinuum is a kind of broadband coherent light source formed by combining laser and fiber technology. With the advantages of wide coverage, good coherence and high brightness, it has attracted wide attention and application in many frontier fields such as high-precision spectroscopy, optical frequency metrology, coherent communication, optical frequency comb generation, nonlinear microscopic imaging and environmental gas trace detection.

[0003] Among all the coverage bands of supercontinuum, the mid-infrared region (wavelength range about 2-20 μm) is particularly important due to its unique "molecular fingerprint region" characteristics. The fundamental vibration absorption peaks of most molecules are concentrated in this band, which enables the broadband laser source based on mid-infrared supercontinuum to simultaneously excite and detect the absorption characteristics of multiple molecules, showing irreplaceable application potential in key scenes such as precision spectroscopy analysis, chemical trace sensing, environmental pollutant monitoring and biomedical diagnosis.

[0004] At present, the mainstream generation method of mid-infrared supercontinuum is to realize spectrum broadening by using the nonlinear effect of optical fiber. Specifically, through the nonlinear effects such as four-wave mixing, soliton dynamics and stimulated Raman scattering, femtosecond pulses are broadened to the mid-infrared band by specially designed glass fibers. However, there are still many key problems to be solved in the existing technical solutions:

[0005] In the traditional scheme, although small-core nonlinear optical fibers can provide a higher nonlinear coefficient to promote spectrum broadening, the coupling efficiency with the laser source is extremely low, and is significantly affected by external disturbances such as temperature fluctuations and optical path vibrations, resulting in poor optical path stability during the experiment, making it difficult to achieve long-term stable supercontinuum output.

[0006] Under the condition of free propagation, the pump pulse can only pass through the optical fiber once to interact nonlinearly, which limits the efficiency of nonlinear effects, not only making it difficult to break through the bottleneck of spectrum broadening, but also having the problem of low energy utilization rate, which cannot fully utilize the energy potential of pump light and restricts the expansion of application scenarios of mid-infrared supercontinuum.

[0007] The existing system cannot compensate for the cavity length deviation caused by external disturbances and optical path drift in real time, making it difficult to maintain the matching between the round-trip time of signal light in the resonant cavity and the pump pulse period, and further causing problems such as spectral frequency shift and intensity fluctuation, which seriously affect the output quality and stability of supercontinuum.

[0008] Therefore, developing a technical scheme capable of solving the above problems of poor stability, limited spectral broadening, and lack of active regulation, and realizing long-term stable output of mid-infrared supercontinuum spectrum, becomes a technical demand urgently needed to be solved in the field. SUMMARY

[0009] Therefore, it is necessary to provide an active locking system and method for mid-infrared supercontinuum spectrum to solve at least one problem existing in the prior art.

[0010] In a first aspect, the embodiments of the present application are implemented in the following manner. An active locking system for mid-infrared supercontinuum spectrum is provided, comprising:

[0011] A pump light generation module is configured to output pump light and split the pump light into at least two beams.

[0012] A main light path processing module is configured to receive one beam of pump light output by the pump light generation module, perform light signal optimization processing, and then couple the pump light into an optical fiber for spectral broadening.

[0013] A reference signal generation module is configured to receive another beam of pump light output by the pump light generation module and convert the pump light into a reference signal.

[0014] An optical cavity length control module is configured to receive the light signal after spectral broadening and perform optical cavity length control.

[0015] A reference signal generation module is configured to perform multi-stage splitting on the light signal after optical cavity length control, extract a target split light signal for feedback, and convert the target split light signal into a reference signal.

[0016] A feedback control module is configured to generate a correction voltage based on the reference signal and the reference signal to drive the optical cavity length control module to actively lock the cavity length.

[0017] In a possible implementation, the pump light generation module comprises:

[0018] A laser is configured to output pump light.

[0019] A first beam splitter is arranged on a propagation path of the pump light and configured to split the pump light into at least two beams.

[0020] In a possible implementation, the main light path processing module comprises:

[0021] A light path collimation device is configured to receive one beam of pump light output by the pump light generation module and perform light path collimation processing.

[0022] A stray light filtering device is configured to filter out stray light in the pump light after light path collimation processing.

[0023] a coupling element for coupling the filtered pump light to the optical fiber, wherein the input end of the optical fiber is located at a focal point of the coupling element.

[0024] In a possible implementation, the reference signal generation module comprises:

[0025] a first photodetector for receiving another pump light output by the pump light generation module and converting the another pump light into a first raw electrical signal as the reference signal.

[0026] In a possible implementation, the system further comprises:

[0027] an optical path turning and filtering module for turning the optical path of the spectrum-broadened light signal and filtering the idler light of the spectrum-broadened light signal, and then transmitting the spectrum-broadened light signal to the optical cavity length control module;

[0028] The optical path turning and filtering module comprises:

[0029] a first reflecting element for receiving the spectrum-broadened light signal and changing the optical path direction of the spectrum-broadened light signal;

[0030] a filter for filtering the idler light of the spectrum-broadened light signal after the optical path direction of the spectrum-broadened light signal is changed;

[0031] a second reflecting element for reflecting the filtered light signal to the optical cavity length control module.

[0032] In a possible implementation, the optical cavity length control module comprises:

[0033] a first collimating and focusing element for focusing the light signal reflected by the second reflecting element to a jumper wire to be incident on a resonant cavity;

[0034] an optical fiber vibrator for controlling the cavity length of the resonant cavity by mechanical deformation, so that the light signal satisfies the resonance condition;

[0035] a second collimating and focusing element for collimating the light signal after the cavity length is controlled and transmitting the light signal to the reference signal generation module;

[0036] The first collimating and focusing element, the optical fiber vibrator, and the second collimating and focusing element are coaxially arranged in sequence, and the optical fiber vibrator is arranged on the confocal path between the first collimating and focusing element and the second collimating and focusing element.

[0037] In a possible implementation, the reference signal generation module comprises:

[0038] a second beam splitter for splitting the light signal after the optical cavity length is controlled into at least two light signals, wherein one of the light signals output by the second beam splitter is reflected and then transmitted back to the optical fiber to form a circulating light path;

[0039] a third beam splitter, configured to split another light signal output by the second beam splitter into at least two light signals, wherein the second beam splitter and the third beam splitter are coaxially arranged;

[0040] a second photodetector, configured to convert a light signal output by the third beam splitter into a second original electrical signal as the reference signal.

[0041] In a possible implementation, the feedback control module comprises:

[0042] a first phase-locked loop, configured to perform frequency tracking and phase calibration on the reference signal to output a reference frequency signal having the same frequency and phase as the reference signal;

[0043] a second phase-locked loop, configured to perform frequency tracking and phase calibration on the reference signal to output a reference frequency signal having the same frequency and phase as the reference signal;

[0044] a controller, connected to the first phase-locked loop and the second phase-locked loop respectively, configured to generate a correction voltage based on the reference frequency signal and the reference frequency signal to drive the optical cavity length control module to actively lock the cavity length.

[0045] In a second aspect, an active locking method of a mid-infrared supercontinuum is provided, comprising:

[0046] outputting a pump light by a laser, and splitting the pump light into at least two light signals;

[0047] performing optical optimization on one of the pump light signals, and inputting the pump light signal into an optical fiber to perform spectral broadening;

[0048] converting another pump light signal into a reference signal;

[0049] performing optical cavity length control on the light signal after spectral broadening;

[0050] performing multi-stage splitting on the light signal after optical cavity length control, extracting a target split light signal for feedback, and converting the target split light signal into a reference signal;

[0051] generating a correction voltage based on the reference signal and the reference signal to actively lock the cavity length.

[0052] In a possible implementation, the generating of the correction voltage based on the reference signal and the reference signal to actively lock the cavity length comprises:

[0053] performing frequency tracking and phase calibration on the reference signal and the reference signal respectively to output a reference frequency signal having the same frequency and phase as the reference signal, and a reference frequency signal having the same frequency and phase as the reference signal;

[0054] generate a correction voltage based on a difference between the reference frequency signal and the benchmark frequency signal;

[0055] drive a fiber stretcher to generate mechanical deformation based on the correction voltage to adjust a cavity length of the optical cavity;

[0056] match a round-trip time of the optical signal in the optical cavity with a pump pulse period through the cavity length adjustment until the difference between the reference frequency signal and the benchmark frequency signal tends to zero, and achieve active locking of the cavity length.

[0057] The active locking system and method of the above mid-infrared supercontinuum spectrum, the system comprises: a pump light generation module, configured to output pump light and split the pump light into at least two paths; a main light path processing module, configured to receive one path of pump light output by the pump light generation module, perform optical signal optimization processing, and then couple the pump light into an optical fiber to perform spectrum broadening; a benchmark signal generation module, configured to receive another path of pump light output by the pump light generation module and convert the pump light into a benchmark signal; an optical cavity length control module, configured to receive the optical signal after spectrum broadening and perform optical cavity length control; a reference signal generation module, configured to perform multi-stage splitting on the optical signal after optical cavity length control, extract a target split optical signal for feedback, and convert the target split optical signal into a reference signal; and a feedback control module, configured to generate a correction voltage based on the benchmark signal and the reference signal to drive the optical cavity length control module to perform active locking of the cavity length.

[0058] In the embodiments of the present application, through modularized collaborative design of pump light generation, main light path processing, benchmark and reference frequency signal generation, optical cavity length control and feedback control, a closed-loop active locking system is constructed. On the one hand, the system fully improves the spectrum broadening efficiency by using optical signal optimization processing and fiber nonlinear effect, solves the problems of limited broadening and low energy utilization rate caused by low traditional fiber nonlinear coefficient, and on the other hand, through real-time comparison and feedback adjustment of the benchmark and reference frequency signals, the fiber stretcher is driven to accurately adjust the cavity length of the optical cavity, effectively compensates for the deviation caused by external interference and light path drift, realizes stable matching of the round-trip time of the signal light and the pump pulse period, significantly improves the anti-interference ability and long-term working stability of the system, and finally outputs a mid-infrared supercontinuum spectrum with sufficient bandwidth and stable frequency, which meets the application requirements of high-performance mid-infrared light sources in the fields of precision spectroscopy, chemical sensing, environmental monitoring and the like. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0060] Figure 1 is a structural schematic of an active locking system of a mid-infrared supercontinuum in an embodiment of the present application Figure 1 ;

[0061] Figure 2 is a structural schematic of an active locking system of a mid-infrared supercontinuum in an embodiment of the present application Figure 2

[0062] Figure 3 is a structural schematic of an optical fiber in an embodiment of the present application

[0063] Figure 4 is a flow schematic of an active locking method of a mid-infrared supercontinuum in an embodiment of the present application

[0064] Figure 5 is a schematic diagram of a computer device in an embodiment of the present application

[0065] In the embodiment, 100 is a pump light generation module; 200 is a main light path processing module; 300 is a reference signal generation module; 400 is an optical cavity length control module; 500 is a reference signal generation module; 600 is a feedback control module; 1 is a laser; 2 is a first beam splitter; 3 is a light path collimation component; 4 is a stray light filtering component; 5 is a coupling component; 6 is an optical fiber; 7 is a first reflecting component; 8 is a filter; 9 is a second reflecting component; 10 is a first collimating and focusing component; 11 is a second collimating and focusing component; 12 is a third reflecting component; 13 is a second beam splitter; 14 is a third beam splitter; 15 is a spectrometer; 16 is a second photodetector; 17 is a first photodetector; 18 is a second phase-locked loop; 19 is a first phase-locked loop; 20 is a controller; and 21 is an optical fiber vibrator. DETAILED DESCRIPTION

[0066] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0067] Embodiment one,

[0068] In an embodiment of the present application, as Figure 1As shown, an active locking system for mid-infrared supercontinuum is provided. The active locking system for mid-infrared supercontinuum includes a pump light generation module 100, a main optical path processing module 200, a reference signal generation module 300, an optical cavity length adjustment module 400, a reference signal generation module 500, and a feedback control module 600. The functional modules are described in detail below: Pump light generation module 100, used to output pump light and split the pump light into at least two paths; Main optical path processing module 200, used to receive one pump light output from the pump light generation module, perform optical signal optimization processing, and couple it into optical fiber 6 for spectral broadening; Reference signal generation module 300, used to receive the other pump light output from the pump light generation module and convert it into a reference signal; Optical cavity length adjustment module 400, used to receive the spectrally broadened optical signal and perform optical cavity length adjustment; Reference signal generation module 500, used to perform multi-level beam splitting on the optical signal after optical cavity length adjustment, extract the target beam splitting optical signal for feedback, and convert it into a reference signal; Feedback control module 600, used to generate a correction voltage based on the reference signal and the reference signal to drive the optical cavity length adjustment module to actively lock the cavity length. In this embodiment, optical signal optimization processing and fiber nonlinear effects are used to significantly improve spectral broadening efficiency, solving the problems of limited broadening and low energy utilization caused by the low nonlinear coefficient of traditional optical fibers. Furthermore, by comparing and adjusting the reference frequency signals in real time, the fiber optic vibrator is driven to precisely adjust the cavity length of the resonant cavity, effectively compensating for deviations caused by external interference and optical path drift. This achieves stable matching between the round-trip time of the signal light and the pump pulse period, significantly improving the system's anti-interference capability and long-term operational stability. Ultimately, the output is a mid-infrared supercontinuum with sufficient bandwidth and stable frequency, meeting the application requirements of high-performance mid-infrared light sources in fields such as precision spectroscopy, chemical sensing, and environmental monitoring.

[0069] like Figure 2 As shown in one embodiment of this application, the pump light generation module 100 includes: a laser 1, which outputs pump light; and a first beam splitter 2, disposed on the propagation path of the pump light, for splitting the pump light into at least two beams. Specifically, the laser 1 can be a femtosecond pulse laser, a tuned laser, etc., for outputting pump light to the propagation path according to actual needs. The first beam splitter can stably split the pump light output by the laser 1 into at least two beams according to the optical path requirements using a specific splitting ratio. One beam is used for spectral broadening of the main optical path to generate a supercontinuum, and the other beam is used to generate a reference signal, providing a comparison reference for active locking of the system. This realizes the functional separation and coordination of energy input and reference calibration, and is the hardware foundation for the system to achieve active locking of the mid-infrared supercontinuum.

[0070] The repetition frequency of laser 1 can be 100MHz, and the single pulse energy... The center wavelength can be 1980 nm.

[0071] It should be noted that the specific splitting ratio can be dynamically adjusted according to the optical path requirements, for example, it can be 9:1, that is, 90% of the light is used to input the main optical path processing module, and after optimized processing, it is introduced into the optical fiber 6 for spectral broadening; 10% of the light is used to input the reference signal generation module 300, and after processing, it is used as a reference signal.

[0072] As shown in Figure 2 In an embodiment of the present application, the main optical path processing module 200 is composed of an optical path collimation member 3, a stray light filtering member 4 and a coupling member 5, wherein the optical path collimation member 3 is used to receive one pump light output by the pump light generation module and perform optical path collimation processing; the stray light filtering member 4 is used to filter out stray light in the pump light after optical path collimation processing; the coupling member 5 is used to couple the pump light after filtering out stray light to the optical fiber 6, wherein the input end of the optical fiber 6 is located at the focal point of the coupling member 5.

[0073] Specifically, the optical path collimation member 3 first receives one pump light output by the pump light generation module 100, and corrects the light beam that may have divergence or angle deviation to parallel light through accurate collimation processing, effectively reducing the energy dispersion and loss of the light beam in the subsequent transmission process; then, the stray light filtering member 4 performs targeted stray light filtering on the collimated light beam, which can efficiently eliminate the mixed background noise, out-of-band interference light and scattered light in the pump light, significantly improve the signal purity of the incident light, avoid the entry of stray light into the optical fiber to cause unexpected nonlinear interference or energy loss, and ensure the controllability of the spectral broadening process; finally, the coupling member 5 focuses and couples the filtered pure pump light to the optical fiber 6, and by accurately setting the input end of the optical fiber 6 at the focal point of the coupling member, the focused light beam energy is highly concentrated and optimally matched with the optical fiber core diameter, which maximally reduces the coupling loss and efficiently injects more pump light energy into the optical fiber.

[0074] The optical path collimation member 3 can be a collimator, and the focal length thereof can be 100 mm.

[0075] The stray light filtering member 4 can be a dichroic mirror, and the transmittance of the dichroic mirror to the pump light is greater than 90%, and the reflectivity of the dichroic mirror to the signal light is greater than 95%, which can feedback the signal light to the optical cavity.

[0076] The coupling member 5 can be a focusing lens, and the focal length thereof can be 40 mm.

[0077] As shown in Figure 3As shown, the optical fiber 6 can be a tapered hollow optical fiber which can be made of fluorotellurite glass, the optical fiber 6 has three air holes at the cladding, the total length of the optical fiber 6 is 6 cm, wherein the undeformed region is 1 cm long, the transition region is 3 cm long, and the tapered region is 2 cm long, the zero dispersion wavelength of the optical fiber 6 is 2 um, and when the pump light is transmitted in the optical fiber 6, the spectrum is broadened through the nonlinear effect (such as four-wave mixing, stimulated Raman scattering, etc.) thereof, and finally the mid-infrared supercontinuum spectrum is output.

[0078] It should be noted that the tapered hollow optical fiber made of fluorotellurite glass is used as the nonlinear medium in the present application, and the optical fiber has a segmented structure of an undeformed region, a transition region and a tapered region: the undeformed region can ensure high coupling efficiency with the laser source and provide guarantee for efficient injection of pump light; the tapered region can significantly improve the nonlinear coefficient of the optical fiber by reducing the effective mode area, and can strengthen the excitation efficiency of nonlinear effect. Meanwhile, the core of the optical fiber is surrounded by three cladding air holes, and under the synergistic action of small core size and high refractive index contrast between the core and the cladding, the pump light can be strongly constrained, the energy leakage of the optical field can be reduced, and the nonlinear interaction can be further enhanced. The synergistic advantages of the above structure design can greatly improve the spectrum broadening effect, and provide key support for efficient generation of mid-infrared supercontinuum spectrum.

[0079] As shown in the embodiment of the present application, Figure 2 As shown in the embodiment of the present application, the reference signal generation module 300 includes a first photodetector 17 for receiving another pump light output by the pump light generation module and converting it into a first original electric signal, and the electric signal is directly used as the reference signal of the system active locking. Since the pump light and the pump light source for spectrum broadening in the main light path are derived from the same laser, they have the same origin, so that the converted reference signal can truly reflect the original frequency, phase and other characteristics of the pump light, and provide a stable and comparable standard reference for the subsequent feedback control module to compare and reference signals and judge the cavity length deviation, which is the key basis for ensuring the accuracy of the system active locking.

[0080] The bandwidth of the first photodetector 17 is greater than 10 GHz. The first photodetector 17 is configured to convert the received optical signal into an electric signal.

[0081] In one embodiment of this application, the system further includes an optical path redirection and filtering module, used to redirect and filter the optical signal after spectral broadening, before transmitting it to the optical cavity length control module 400. The optical path redirection and filtering module may include a first reflector 7, a filter 8, and a second reflector 9 arranged sequentially. The first reflector 7 receives the spectrally broadened optical signal and changes its optical path direction; the filter 8 performs idler filtering on the optical signal after the optical path direction change; and the second reflector 9 reflects the filtered optical signal to the optical cavity length control module 400. Specifically, the first reflector 7 receives the spectrally broadened optical signal and adjusts the light propagation path by changing its optical path direction; the filter 8 performs idler filtering on the optical signal after the direction change, eliminating non-target band idler light and stray light generated during spectral broadening; and the second reflector 9 reflects the filtered pure optical signal to the optical cavity length control module 400, ensuring that the optical signal enters the cavity length control stage with stable energy and direction. The optical path is adapted to the overall structural layout of the system, and the quality of the optical signal entering the control module is ensured by the idle frequency optical filtering, so as to provide a reliable original signal basis for subsequent precise cavity length control.

[0082] Both the first reflector 7 and the second reflector 9 can be mirrors, such as gold-plated quartz glass mirrors. These mirrors have high reflectivity in the mid-infrared band, which can reduce the energy loss of optical signals and ensure stable signal strength.

[0083] Among them, filter 8 can be a dedicated infrared filter device. This type of filter can achieve high transmittance for specific mid-infrared bands, while effectively suppressing idler light and improving the purity of the optical signal.

[0084] It should be noted that the laser 1, the first beam splitter 2, the optical path collimator 3, the stray light filter 4, the coupler 5, and the first reflector 7 are arranged coaxially in sequence. The input end of the optical fiber 6 is located at the focal point of the coupler 5 and is used to generate a supercontinuum. The first reflector 7 is located on the light propagation path at the output end of the optical fiber 6 and is adapted to the subsequent optical path.

[0085] like Figure 2As shown, in an embodiment of the present application, the optical cavity length control module 400 is composed of the first collimating and focusing element 10, the fiber oscillator 21 and the second collimating and focusing element 11 in sequence, which bears the functions of focusing, cavity length control and collimating transmission of the optical signal. Specifically, the first collimating and focusing element 10 receives the optical signal sent by the second reflecting element 9 and performs focusing processing on it, and guides it into the jumper wire to be incident to the resonant cavity; the fiber oscillator 21 can change the propagation path length of the optical signal in the cavity by its own deformation, so as to realize dynamic control of the cavity length; and the second collimating and focusing element 11 collimates and transmits the optical signal after the cavity length control to the reference signal generation module 500, so that the optical signal energy is concentrated by the focusing effect and is coupled to the subsequent module efficiently, thereby ensuring the accuracy of the reference signal generation.

[0086] The first collimating and focusing element 10 and the second collimating and focusing element 11 can be aspherical lenses, such as quartz glass mirrors coated with infrared coatings, and the focal length thereof can be 4.6 mm. The coating can improve the transmittance of the mid-infrared waveband optical signal and reduce energy loss, and the focal length of 4.6 mm can adapt to the divergence angle of the optical signal to ensure accurate collimation effect.

[0087] The fiber oscillator 21 can be a PZT fiber vibrator, and the displacement resolution of the PZT fiber vibrator is better than 10 nm, and the corresponding cavity length adjustment range can be ±10 μm. When the PZT is deformed, the length of the optical fiber wound on the surface of the PZT changes slightly, so that the optical path changes, thereby realizing accurate adjustment of the resonant cavity length and matching the signal light round-trip time with the pump light pulse period.

[0088] It should be noted that the first collimating and focusing element 10, the fiber oscillator 21 and the second collimating and focusing element 11 are coaxially arranged in sequence, and the fiber oscillator 21 is arranged on the confocal path between the first collimating and focusing element 10 and the second collimating and focusing element 11, i.e. at the intermediate focal point therebetween, for adjusting the optical path size. The coaxial arrangement of the three ensures stable transmission of the optical signal during the control process, and provides hardware support for real-time dynamic adjustment of the cavity length through the precise deformation response of the fiber vibrator, which is a key execution link for realizing active locking of the system.

[0089] As shown in FIG. 4, the optical cavity length control module 400 is composed of the first collimating and focusing element 10, the fiber oscillator 21 and the second collimating and focusing element 11 in sequence, which bears the functions of focusing, cavity length control and collimating transmission of the optical signal. Specifically, the first collimating and focusing element 10 receives the optical signal sent by the second reflecting element 9 and performs focusing processing on it, and guides it into the jumper wire to be incident to the resonant cavity; the fiber oscillator 21 can change the propagation path length of the optical signal in the cavity by its own deformation, so as to realize dynamic control of the cavity length; and the second collimating and focusing element 11 collimates and transmits the optical signal after the cavity length control to the reference signal generation module 500, so that the optical signal energy is concentrated by the focusing effect and is coupled to the subsequent module efficiently, thereby ensuring the accuracy of the reference signal generation. Figure 2As shown, in an embodiment of the present application, the reference signal generation module 500 constructs a recycling and reference signal extraction link of the optical signal through multi-stage beam splitting and photoelectric conversion, specifically including a second beam splitter 13, a third beam splitter 14 and a second photodetector 16 in turn. The second beam splitter 13 is used to split the optical signal after optical cavity length regulation into at least two paths, wherein one path of the optical signal output by the second beam splitter 13 is reflected back into the optical fiber 6 to form a recycling light path. The third beam splitter 14 is used to split another path of the optical signal output by the second beam splitter 13 into at least two paths. The second beam splitter 13 is coaxially arranged with the stray light filter 4, and the optical signal reflected back into the optical fiber 6 by the second beam splitter 13 forms a closed annular loop after being reflected by the stray light filter 4. The second beam splitter 13 and the third beam splitter 14 are coaxially arranged. The second photodetector 16 is used to convert one path of the optical signal output by the third beam splitter 14 into a second original electrical signal as the reference signal. By feeding back part of the signal light into the optical fiber 6, a stable annular cavity structure is formed. The optical signal is transmitted in the cavity multiple times, significantly enhancing the interaction between pulses, allowing nonlinear effects such as self-phase modulation and stimulated Raman scattering to gradually accumulate and amplify in the cavity, thereby effectively improving the energy utilization rate of the pump light and optimizing the bandwidth and flatness of the supercontinuum spectrum.

[0090] Specifically, the optical signal after optical cavity length regulation output by the second collimating and focusing element 11 changes direction after passing through the third reflecting element 12, enters the second beam splitter 13, and the second beam splitter 13 splits it into at least two paths according to the light path requirement with a specific splitting ratio. One path of the optical signal is reflected back into the optical fiber 6 to form a closed loop recycling light path, so that the optical signal repeatedly excites nonlinear effects in the optical fiber 6 multiple times, improving the efficiency and bandwidth of spectral broadening and solving the problem of limited nonlinear effects caused by traditional single-pass optical fiber. The third beam splitter 14 is coaxially arranged with the second beam splitter 13, receives and splits another path of the optical signal output by the second beam splitter, and further splits it into at least two paths to ensure the coaxiality and stability of the light path transmission. The second photodetector 16 receives one path of the optical signal output by the third beam splitter 14 and converts it into a second original electrical signal through photoelectric conversion. The electrical signal is used as a reference signal to compare with the reference signal generated by the reference signal generation module. Through the cooperative design of multi-stage beam splitting, not only the efficient recycling of the optical signal is realized, but also the reference signal for feedback is accurately extracted, which provides a direct basis for the subsequent feedback control module to judge the cavity length deviation and drive regulation. It is the key signal source of the system closed-loop locking logic.

[0091] It should be noted that the specific splitting ratio can be dynamically adjusted according to the light path requirements. For example, the specific splitting ratio of the second beam splitter 13 can be 1:1, that is, 50% of the light is reflected back into the optical fiber 6 to form a closed loop circulation, which is used to maintain the optical resonance and accumulate the nonlinear effect to enhance the spectral broadening effect. In addition, 50% of the light enters the third beam splitter 14 for splitting again. The specific splitting ratio of the third beam splitter 14 can be 3:7, that is, 30% of the light enters the second photodetector 16, which converts the optical signal into an electrical signal and inputs it into the second phase-locked loop 18 for processing to generate a reference frequency signal. In addition, 70% of the light enters the spectrometer 15 for real-time monitoring of the spectral broadening effect and generating a spectrum graph to analyze the spectral distribution of the signal light.

[0092] The bandwidth of the second photodetector 16 is for converting the received optical signal into an electrical signal.

[0093] The wavelength range of the spectrometer 15 can be 1500-5000nm, and the resolution can be set to , the wavelength accuracy can be , and the dynamic range can be .

[0094] The third reflecting element 12 can be a mirror, such as a gold-coated quartz glass mirror, which has high reflectivity in the mid-infrared band, reducing the loss of optical signal energy and ensuring stable signal strength.

[0095] As shown in Figure 2 , in an embodiment of the present application, the feedback control module 600 includes a first phase-locked loop 19 for frequency tracking and phase calibration of the reference signal to output a reference frequency signal with the same frequency and phase as the reference signal; a second phase-locked loop 18 for frequency tracking and phase calibration of the reference signal to output a reference frequency signal with the same frequency and phase as the reference signal; and a controller 20 connected to the first phase-locked loop 19 and the second phase-locked loop 18, respectively, for generating a correction voltage based on the reference frequency signal and the reference frequency signal to drive the optical cavity length control module 400 to actively lock the cavity length. Real-time compensation of the length drift of the optical fiber by the feedback control module can effectively suppress the timing mismatch caused by the cavity length drift under complex environmental conditions such as temperature fluctuations, air disturbances, and mechanical vibrations, thereby ensuring stable coincidence of the pump pulse and the cavity pulse, and realizing long-term stable output of the supercontinuum spectrum.

[0096] Specifically, the first photodetector 17 is connected with the first phase-locked loop 19, and the second photodetector 16 is connected in communication with the second phase-locked loop 18. The first phase-locked loop 19 and the second phase-locked loop 18 are respectively connected in communication with the controller 20, and the controller 20 is connected in communication with the fiber oscillator 21. The first phase-locked loop 19 and the second phase-locked loop 18 respectively generate the reference frequency signal and the reference frequency signal with stable frequency characteristics through internal frequency tracking and phase locking mechanisms for the two original electrical signals generated by the first photodetector 17 and the second photodetector 16, so as to eliminate random noise and phase drift in signal transmission, ensure the comparability and accuracy of the two frequency signals, and control the controller 20 to compare the differences (such as frequency offset and phase difference) between the reference frequency signal and the reference frequency signal in real time. The controller 20 quantifies the differences into a corresponding correction voltage through a preset control algorithm (such as a proportional-integral-derivative algorithm), and the correction voltage directly drives the fiber oscillator 21 to generate a corresponding mechanical deformation, so that the round-trip time of the signal light in the cavity and the period of the pump pulse are re-matched, the real-time feedback adjustment and active locking of the resonant cavity length are realized, and the long-term stable output of the supercontinuum spectrum is realized.

[0097] It should be noted that when the difference between the two frequency signals decreases, the correction voltage gradually converges; when the difference increases, the voltage is quickly adjusted to compensate for the deviation, and finally the stable matching of the reference frequency signal and the reference frequency signal is realized, and the long-term locking of the resonant cavity length in the target state is ensured.

[0098] The working frequency range of the first phase-locked loop 19 and the second phase-locked loop 18 can cover

[0099] , and the locking accuracy is better than .

[0100] The controller 20 can be a proportional-integral-derivative controller, which realizes precise regulation through the synergistic effect of proportional, integral, and derivative links: the proportional link (P) outputs a correction voltage proportional to the real-time deviation of the reference frequency signal from the reference frequency signal, quickly responds to the current error; the integral link (I) accumulates historical deviations and outputs a corresponding voltage, gradually eliminating static errors and ensuring long-term stability; the derivative link (D) outputs an adjustment signal in advance according to the rate of change of the deviation, suppresses system overshoot and oscillation, and improves response speed. When the reference frequency signal deviates from the reference frequency signal, the controller will dynamically generate an optimized correction voltage based on the calculation results of the three: if the deviation suddenly increases, the proportional link will dominate the rapid adjustment; if the deviation persists, the integral link will gradually eliminate the residual error; if the deviation trend reverses, the derivative link will correct in advance to avoid over-regulation. This multi-dimensional regulation feature enables the controller to adapt to dynamic changes in the cavity length caused by external disturbances (such as temperature fluctuations and mechanical vibrations), ensuring the response accuracy and stability of the optical cavity length regulation module, and ultimately achieving long-term locking of the reference frequency and the reference frequency.

[0101] In the embodiments of the present application, the optical signal optimization processing and the fiber nonlinear effect are used to fully improve the spectral broadening efficiency, solving the problems of limited broadening and low energy utilization caused by low traditional fiber nonlinear coefficient. Through real-time comparison and feedback adjustment of the reference frequency signal and the reference frequency signal, the fiber vibrator is driven to accurately adjust the resonant cavity length, effectively compensating for the deviation caused by external interference and optical path drift, achieving stable matching of the signal light round-trip time and the pump pulse period, significantly improving the anti-interference ability and long-term working stability of the system, and finally outputting a mid-infrared supercontinuum with sufficient bandwidth and stable frequency, meeting the application requirements of high-performance mid-infrared light sources in the fields of precision spectroscopy, chemical sensing, and environmental monitoring.

[0102] The above-mentioned modules in the active locking system of the mid-infrared supercontinuum can be realized by software, hardware, or a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in hardware form, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0103] Embodiment two,

[0104] In an embodiment, a method for actively locking a mid-infrared supercontinuum is provided, which is used to achieve the active locking system of the mid-infrared supercontinuum provided in the above-mentioned embodiment one. As shown in the method, the method comprises the following steps: Figure 4

[0105] In step S110, a laser outputs pump light, and the pump light is split into at least two paths;​

[0106] Specifically, the laser 1 can be a femtosecond pulse laser, a tunable laser, etc., for outputting pump light with specific parameters (such as femtosecond pulse characteristics) to the propagation path according to actual needs, and the first beam splitter can stably split the pump light into at least two paths according to the light path requirements, one of which is used for spectral broadening in the main light path to generate a supercontinuum spectrum, and the other is used to generate a reference signal to provide a comparison reference for active locking of the system, thereby realizing the separation and cooperation of energy input and reference calibration functions.

[0107] The repetition frequency of the laser 1 can be 100 MHz, the single pulse energy , and the center wavelength can be 1980 nm.

[0108] It should be noted that the specific splitting ratio can be dynamically adjusted according to the light path requirements, for example, it can be 9:1, that is, 90% of the light is introduced into the optical fiber 6 for spectral broadening after being optimized by the main light path processing module. 10% of the light is processed by the reference signal generation module 300 and used as a reference signal.

[0109] In step S120, one of the pump lights is subjected to light optimization processing and then input into an optical fiber for spectral broadening.

[0110] Optionally, one of the pump lights is subjected to precise collimation processing to correct the light beam that may have divergence or angular deviation to parallel light, effectively reducing the energy dispersion and loss of the light beam in the subsequent transmission process; then, the collimated light beam is subjected to targeted stray light filtering to efficiently eliminate the mixed background noise, out-of-band interference light and scattered light in the pump light, significantly improving the signal purity of the incident light, avoiding the entry of stray light into the optical fiber to cause unexpected nonlinear interference or energy loss, and ensuring the controllability of the spectral broadening process; finally, the filtered pure pump light is focused and coupled to the optical fiber 6, and the pump light is subjected to the synergistic action of multiple nonlinear effects in the optical fiber 6 to achieve efficient spectral broadening to the mid-infrared band.

[0111] Specifically, the optical fiber 6 can generate frequency chirp and expand the spectral edge by self-phase modulation; form multiple high-order solitons through soliton fission to further broaden the spectrum; transfer energy to longer wavelengths by stimulated Raman scattering to extend the spectral line to the mid-infrared region; and generate new frequency components through four-wave mixing when the dispersion and nonlinear conditions match. Under the combined action of the above nonlinear effects, the spectrum is broadened to the mid-infrared band, and the output light can contain signal light and idler light.

[0112] In step S130, the other pump light is converted into a reference signal.

[0113] Optionally, the other way of the split pump light is introduced into the first photodetector 17, and the optical signal is converted into an electrical signal by photoelectric conversion as a reference signal. Since the pump light and the pump light for spectral broadening come from the same laser, the core characteristics such as frequency and phase remain consistent, so the converted reference signal can truly reflect the original characteristics of the pump light, provide a stable standard scale for subsequent comparison with the reference signal, and is the basis for realizing system closed-loop feedback and active locking.

[0114] In step S140, the optical cavity length of the light signal after spectral broadening is controlled;

[0115] Optionally, the light signal after spectral broadening is focused to a jumper to be incident to the resonant cavity; then the physical length of the resonant cavity is accurately adjusted by the optical fiber vibrator through mechanical deformation to compensate for the cavity length drift caused by external interference (such as temperature fluctuation and vibration), the round trip path length of the light signal in the resonant cavity is corrected in real time to ensure that it is stably matched with the pump pulse period, and a stable light signal basis is provided for the generation of the reference signal, which is a key execution step for maintaining the long-term locking state of the system.

[0116] The fiber oscillator 21 can be a PZT optical fiber vibrator, and the displacement resolution of the PZT optical fiber vibrator is better than 10 nm, and the corresponding cavity length adjustment range can be ±10 μm. The optical fiber inside the PZT optical fiber vibrator is wound on the surface of the PZT. When the PZT deforms, the length of the optical fiber changes slightly, thereby changing the optical path and accurately adjusting the cavity length of the resonant cavity, and then matching the signal light round trip time with the pump light pulse period.

[0117] The relationship between the cavity length and the repetition frequency satisfies the following formula:

[0118] ;

[0119] ;

[0120] Wherein, T represents the time of the light signal in the resonant cavity for one round trip, L represents the cavity length of the resonant cavity, i.e. the total length of the light signal in the cavity for one round trip is the group velocity, which is the propagation speed of the signal envelope, reflecting the transmission speed of the signal energy, represents the repetition frequency of the light signal, i.e. the number of times the light signal returns to the resonant cavity per unit time. When the PZT optical fiber vibrator changes the cavity length, the repetition frequency will be adjusted accordingly, thereby adjusting the repetition frequency of the signal light.

[0121] In step S150, the light signal after optical cavity length control is split by multiple stages, and the target split light signal for feedback is extracted and converted into a reference signal;

[0122] Optionally, the light signal after the optical cavity length regulation enters the second beam splitter and is split into at least two paths, one of which is reflected back to the optical fiber to form a circulating light path to enhance the spectral broadening effect, and the other is input into the third beam splitter coaxially arranged with the second beam splitter; the third beam splitter further splits the light signal into at least two paths to ensure the stability of the light path transmission; finally, a specific path of the multiple light signals output from the third beam splitter is selected to input into the second photodetector 16, and the light signal is converted into an electrical signal, i.e. a reference signal, through photoelectric conversion. Through the multi-stage beam splitting design, the recycling of the light signal (improving the spectral broadening efficiency) is realized, and the target light signal for feedback is accurately separated, and the converted reference signal carries the characteristics of the light signal after the cavity length regulation, which can be compared with the reference signal to provide a direct basis for subsequent judgment of the cavity length deviation.

[0123] In step S160, a correction voltage is generated based on the reference signal and the reference signal to actively lock the cavity length.

[0124] Optionally, the reference signal and the reference signal are processed by the first phase-locked loop 19 and the second phase-locked loop 18 respectively, and through frequency tracking, phase locking and noise suppression, the two original electrical signals are purified into reference frequency signals and reference frequency signals with stable frequency characteristics, eliminating interference in signal transmission and ensuring the comparability of the two frequency signals; then, the controller compares the difference (such as frequency offset and phase difference) between the reference frequency signal and the reference frequency signal in real time, and quantizes the difference into a corresponding correction voltage according to a preset algorithm, and drives the optical fiber vibrator to adjust the resonant cavity length. Through this dynamic feedback process, when the cavity length drifts due to external interference (such as temperature and vibration), the reference frequency signal will change accordingly, and the controller compensates for the deviation in real time through the correction voltage, so that the reference frequency signal and the reference frequency signal finally remain stable and matched, realizing the active locking of the optical cavity length and providing core control protection for the stable output of the mid-infrared supercontinuum spectrum.

[0125] In the embodiment of the present application, a method for actively locking a mid-infrared supercontinuum spectrum is provided, which comprises: outputting pump light by a laser, and splitting the pump light into at least two paths; inputting one path of the pump light into an optical fiber for spectrum broadening after performing optical optimization processing on the pump light; converting another path of the pump light into a reference signal; performing optical cavity length control on the light signal after spectrum broadening; extracting a target split light signal for feedback after splitting the light signal after optical cavity length control into multiple stages, and converting the target split light signal into a reference signal; and generating a correction voltage based on the reference signal and the reference signal to actively lock the cavity length. In the embodiment of the present application, the spectrum broadening efficiency is fully improved by using optical signal optimization processing and fiber nonlinear effect, the problems of limited broadening and low energy utilization caused by low traditional fiber nonlinear coefficient are solved, and through real-time comparison and feedback adjustment of the reference and reference frequency signals, the fiber vibrator is precisely adjusted to adjust the resonant cavity length, the deviation caused by external interference and optical path drift is effectively compensated, the stable matching of the signal light round trip time and the pump pulse period is realized, the anti-interference ability and long-term working stability of the system are significantly improved, and finally the mid-infrared supercontinuum spectrum with sufficient bandwidth and stable frequency is output, which meets the application requirements of high-performance mid-infrared light source in the fields of precision spectroscopy, chemical sensing, environmental monitoring and the like.

[0126] In an embodiment of the present application, based on the reference signal and the reference signal, a correction voltage is generated to actively lock the cavity length, comprising:

[0127] The reference signal and the reference signal are subjected to frequency tracking and phase calibration respectively, and a reference frequency signal with the same frequency and phase as the reference signal and a reference frequency signal with the same frequency and phase as the reference signal are output;

[0128] According to the difference between the reference frequency signal and the reference frequency signal, a correction voltage is generated;

[0129] Based on the correction voltage, a mechanical deformation of the fiber vibrator is generated to adjust the cavity length of the resonant cavity;

[0130] The round trip time of the light signal in the resonant cavity and the pump light pulse period are re-matched through the cavity length adjustment until the difference between the reference frequency signal and the reference frequency signal tends to zero, and the active locking of the cavity length is realized.

[0131] Optionally, by continuously comparing the reference frequency signal with the reference frequency signal, and calculating the frequency difference or phase deviation of the two, as a judgment basis for whether the cavity length deviates from the target state; then, the controller 20 (such as a PID controller) converts this deviation into a corresponding correction voltage, and the larger the deviation, the larger the adjustment range of the correction voltage, ensuring a rapid response to the deviation; the correction voltage directly acts on the optical fiber vibrator, making it produce a mechanical deformation matching the voltage amplitude, which accurately changes the physical length of the resonant cavity, and then adjusts the propagation path of the optical signal in the cavity; the change of the cavity length will affect the round-trip time of the optical signal in real time, so that the round-trip time originally mismatched due to external interference (such as temperature fluctuation, mechanical vibration) and the pump pulse period are re-aligned; this adjustment process is repeated, and as the correction voltage drives the vibrator to fine-tune the cavity length, the cavity length change corrects the round-trip time of the optical signal, and then changes the reference frequency signal, until the difference between the reference frequency signal and the reference frequency signal gradually converges to near zero, at which time the resonant cavity length is stabilized at the target value, and the repetition frequency of the optical signal is highly synchronized with the pump light, and finally the active locking of the cavity length is realized, providing reliable control support for long-term stable output of the mid-infrared supercontinuum spectrum.

[0132] In the embodiments of the present application, the optical signal optimization processing and the fiber nonlinear effect are used to fully improve the spectral broadening efficiency, solve the problem of limited broadening and low energy utilization rate caused by low traditional fiber nonlinear coefficient, and through real-time comparison and feedback adjustment of the reference frequency signal and the reference frequency signal, the fiber vibrator is driven to accurately adjust the resonant cavity length, effectively compensate the deviation caused by external interference and optical path drift, realize stable matching of the signal light round-trip time and the pump pulse period, significantly improve the anti-interference ability and long-term working stability of the system, and finally output the mid-infrared supercontinuum spectrum with sufficient bandwidth and stable frequency, meeting the application requirements of high-performance mid-infrared light source in the fields of precision spectroscopy, chemical sensing, environmental monitoring, etc.

[0133] It should be understood that the size of the serial number of each step in the above embodiments does not mean the order of execution, and the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0134] In one embodiment, a computer device is provided, which can be a terminal device, and its internal structure diagram can be as shown in Figure 5The computer device includes a processor, a memory, and a network interface connected through a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a readable storage medium. The readable storage medium stores computer readable instructions. The network interface of the computer device is configured to communicate with an external terminal through a network connection. The computer readable instructions are executed by the processor to implement the method for actively locking mid-infrared supercontinuum. The readable storage medium provided in the embodiment includes a non-volatile readable storage medium and a volatile readable storage medium.

[0135] In the embodiment of the present application, a computer device is provided, which includes a memory, a processor, and computer readable instructions stored in the memory and executable on the processor. The processor executes the computer readable instructions to implement the steps of the method for actively locking mid-infrared supercontinuum.

[0136] In the embodiment of the present application, a readable storage medium is provided, which stores computer readable instructions. The computer readable instructions are executed by the processor to implement the steps of the method for actively locking mid-infrared supercontinuum.

[0137] Those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments can be completed by computer readable instructions instructing related hardware. The computer readable instructions can be stored in a non-volatile readable storage medium or a volatile readable storage medium. When the computer readable instructions are executed, the processes of the above-mentioned embodiments can be included. Any reference to the memory, storage, database or other medium used in the embodiments of the present application can include non-volatile and / or volatile memory. The non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. The volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0138] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above.

[0139] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. An active locking system for the mid-infrared supercontinuum, characterized in that, The system includes: A pump light generation module is used to output pump light and split the pump light into at least two paths; The main optical path processing module is used to receive one pump light output from the pump light generation module, and after optical signal optimization processing, it is coupled into a tapered hollow optical fiber made of fluorotellurate glass for spectral broadening to generate a mid-infrared supercontinuum. The tapered hollow optical fiber has an undeformed region, a gradient region and a tapered region, and the cladding has three pores. The zero-dispersion wavelength is 2μm. The optical path redirection and filtering module is used to redirect the optical signal after spectral broadening and filter the idler frequency before transmitting it to the optical cavity length control module. The reference signal generation module is used to receive another pump light output from the pump light generation module and convert it into a first original electrical signal of the same origin as the pump light through a first photodetector, which serves as the reference signal. An optical cavity length control module includes a first collimating and focusing element, an optical fiber vibrator, and a second collimating and focusing element arranged coaxially in sequence. The optical fiber vibrator is located on the confocal path between the first collimating and focusing element and the second collimating and focusing element. It is used to receive the optical signal after optical path redirection and filtering, and to control the optical cavity length through the mechanical deformation of the optical fiber vibrator. The reference signal generation module is used to perform multi-stage beam splitting on the optical signal after the optical cavity length is adjusted. The multi-stage beam splitting includes a second beam splitter and a third beam splitter arranged coaxially. One optical signal output from the second beam splitter is reflected back to the tapered hollow optical fiber to form a loop optical path. One optical signal output from the third beam splitter is converted into a second original electrical signal by a second photodetector to serve as a reference signal. The feedback control module includes a first phase-locked loop, a second phase-locked loop, and a controller. The first phase-locked loop performs frequency tracking and phase calibration on the reference signal, and the second phase-locked loop performs frequency tracking and phase calibration on the reference signal. The controller generates a correction voltage based on the calibrated reference frequency signal and the reference frequency signal to drive the fiber optic vibrator of the optical cavity length control module to actively lock the cavity length, so that the round-trip time of the optical signal in the resonant cavity matches the pump pulse period.

2. The active locking system for the mid-infrared supercontinuum as described in claim 1, characterized in that, The pump light generation module includes: A laser, which is used to output pump light; A first beam splitter is disposed in the propagation path of the pump light to split the pump light into at least two beams.

3. The active locking system for the mid-infrared supercontinuum as described in claim 1, characterized in that, The main optical path processing module includes: An optical collimator is used to receive one pump light output from the pump light generation module and perform optical collimation processing. Stray light filter, used to filter out stray light in the pump light after optical path collimation; A coupler is used to couple pump light, after filtering out stray light, to the optical fiber, wherein the input end of the optical fiber is located at the focal point of the coupler.

4. The active locking system for the mid-infrared supercontinuum as described in claim 1, characterized in that, The reference signal generation module includes: A first photodetector is used to receive another pump light output from the pump light generation module and convert it into a first raw electrical signal as the reference signal.

5. The active locking system for the mid-infrared supercontinuum as described in claim 1, characterized in that, The optical path steering and filtering module includes: The first reflector is used to receive the optical signal after spectral broadening and change the direction of the optical path. A filter is used to perform idler frequency filtering on the optical signal after the optical path direction has changed. The second reflector is used to reflect the filtered light signal to the optical cavity length control module.

6. The active locking system for the mid-infrared supercontinuum as described in claim 5, characterized in that, The first collimating and focusing element is used to focus the light signal reflected by the second reflector onto the jumper wire so that it can be incident on the resonant cavity; The fiber optic vibrator is used to adjust the cavity length of the resonant cavity through mechanical deformation so that the optical signal meets the resonance condition. The second collimating and focusing element is used to collimate the optical signal after cavity length adjustment and transmit it to the reference signal generation module.

7. The active locking system for the mid-infrared supercontinuum as described in claim 1, characterized in that, The second beam splitter is used to split the optical signal after the optical cavity length is adjusted into at least two paths; The third beam splitter is used to split the other optical signal output by the second beam splitter into at least two beams.

8. An active locking method for mid-infrared supercontinuum, characterized in that, The method, applied to the active locking system for the mid-infrared supercontinuum as described in any one of claims 1-7, comprises: Pump light is output through a laser, and the pump light is split into at least two paths; After optical optimization processing, one pump light is input into an optical fiber for spectral broadening. Convert the other pump light into a reference signal; Optical cavity length is adjusted for the optical signal after spectral broadening; After the optical cavity length is adjusted, the optical signal is split into multiple beams, the target beam-splitting optical signal for feedback is extracted and converted into a reference signal; Based on the reference signal and the reference signal, a correction voltage is generated to actively lock the cavity length.

9. The active locking method for the mid-infrared supercontinuum as described in claim 8, characterized in that, The step of generating a correction voltage based on the reference signal and the reference signal for active cavity length locking includes: Frequency tracking and phase calibration are performed on the reference signal and the reference signal respectively, and a reference frequency signal with the same frequency and phase as the reference signal and a reference frequency signal with the same frequency and phase as the reference signal are output. A correction voltage is generated based on the difference between the reference frequency signal and the reference frequency signal; The optical fiber vibrator is driven by the correction voltage to generate mechanical deformation in order to adjust the cavity length of the resonant cavity; By adjusting the cavity length, the round-trip time of the optical signal in the resonant cavity is rematched with the pump light pulse period until the difference between the reference frequency signal and the reference frequency signal approaches zero, thus achieving active locking of the cavity length.

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