A miniaturized dual-comb system with fully polarization-maintaining fiber structure

Abstract

The present invention discloses a miniaturized fully polarization-maintaining fiber dual-comb system, belonging to the field of optical frequency combs. The system comprises a fully polarization-maintaining fiber dual-comb optical system and an integrated dual-comb electrical control system. The fully polarization-maintaining fiber dual-comb optical system is composed of a local optical frequency comb and a signal optical frequency comb, each of which includes a fully polarization-maintaining fiber mode-locked laser cavity and a fully polarization-maintaining fiber amplifier. The fully polarization-maintaining fiber mode-locked laser cavity is fabricated using precise fiber cavity length control and multi-layer Bragg coating technology. The integrated dual-comb electrical control system is used to control the cavity length of the fully polarization-maintaining fiber mode-locked laser cavity, thereby generating a dual-comb with a repetition frequency difference in the kilohertz range. This system is used for dual-comb time-of-flight ranging. While reducing the size, the present invention can fully utilize the advantages of the high environmental stability of polarization-maintaining fiber, improve the environmental stability of the dual-comb ranging system, and, combined with the miniaturized integrated dual-comb electrical control system, promote the practical application and commercialization of dual-comb ranging.

Description

Technical Field

[0001] The present invention relates to the field of optical frequency combs, and in particular to a miniaturized full polarization-maintaining optical fiber structure dual optical comb system. Background Art

[0002] An optical frequency comb is a phase-locked, mode-locked laser, named for its unique comb-like distribution in the frequency domain. It boasts a wide spectrum, narrow pulse width, and low phase noise, equivalent to the simultaneous output of hundreds of thousands of phase-locked, narrow-linewidth lasers. This has revolutionized the precision measurement of parameters such as frequency, time, and distance. Absolute distance measurement based on dual optical combs boasts high accuracy, high speed, and a large unambiguous range. It holds broad application prospects in precision manufacturing, aerospace alignment, and high-precision 3D topography scanning.

[0003] Current dual-comb systems are still limited by complex optical and electronic control systems, are bulky and difficult to move, and lack environmental stability, making them difficult to measure outside of laboratory environments. These problems limit the further practical application and product application of dual-comb technology. Summary of the Invention

[0004] In response to the current problems faced by dual-comb systems, the main purpose of the present invention is to provide a miniaturized dual-comb system with a fully polarization-maintaining fiber structure, improve its portability and environmental stability, enable the dual-comb to truly move beyond the laboratory measurement environment and be used for dual-comb time-of-flight ranging, and promote its practical application and productization.

[0005] To achieve the above objectives, the technical solution provided by the present invention is:

[0006] A miniaturized fully polarization-maintaining fiber dual-comb system for dual-comb time-of-flight ranging, comprising a fully polarization-maintaining fiber dual-comb optical system and an integrated dual-comb electronic control system.

[0007] The full polarization-maintaining fiber dual-comb optical system is composed of a local optical frequency comb and a signal optical frequency comb. Both the local optical frequency comb and the signal optical frequency comb include a full polarization-maintaining fiber mode-locked laser cavity and a full polarization-maintaining fiber amplifier. The full polarization-maintaining fiber amplifier is connected to the full polarization-maintaining fiber mode-locked laser cavity. The full polarization-maintaining fiber mode-locked laser cavity is prepared by using fiber cavity length precision control technology and multi-layer Bragg coating technology. Preferably, the full polarization-maintaining fiber mode-locked laser cavity adopts a full polarization-maintaining linear fiber laser cavity based on SESAM mode locking. The SESAM-based mode locking method can be achieved through a SESAM device packaged in a micro-fiber structure, which has the advantages of easy mode locking, small size, and full polarization maintenance.

[0008] The integrated dual-comb electric control system is used to control the cavity length of the full-polarization-maintaining fiber mode-locked laser cavity in the full-polarization-maintaining fiber dual-comb optical system, so as to generate a dual-comb with a repetition frequency difference of the kilohertz order.

[0009] Furthermore, the fully polarization-maintaining fiber-mode-locked laser cavity comprises a first polarization-maintaining fiber and a second polarization-maintaining fiber. One end of the first polarization-maintaining fiber utilizes a semiconductor saturable absorber (SESAM) as a reflective surface, while one end of the second polarization-maintaining fiber utilizes an FC / PC head coated with a multilayer Bragg reflector as an output mirror. The other ends of the first and second polarization-maintaining fibers are fused together. This design minimizes the use of intracavity components, facilitates miniaturization of the laser cavity, and facilitates subsequent precise control of the fiber cavity length.

[0010] Furthermore, the optical fiber cavity length precision control technology and multi-layer Bragg coating technology include:

[0011] (1) preparing a first polarization-maintaining fiber and a second polarization-maintaining fiber, wherein the lengths of the first polarization-maintaining fiber and the second polarization-maintaining fiber exceed the length of the target cavity, one end of the second polarization-maintaining fiber is connected to an original FC / PC head, the original FC / PC head is not coated with a multilayer Bragg reflection film, and one end of the first polarization-maintaining fiber is focused onto the SESAM surface through a micro-encapsulation structure;

[0012] (2) Place the fiber end faces of the first polarization-maintaining fiber and the second polarization-maintaining fiber to be fused in a fiber fusion splicer and align them. Connect the original FC / PC head to the optical frequency domain reflectometer (OFDR). Measure the time difference between the reflection of the probe light at the FC / PC head and the reflection at the SESAM end to obtain the fiber cavity length. Calculate the excess cavity length based on the target cavity length and the measured fiber cavity length.

[0013] (3) Take out the fiber end face of any polarization-maintaining fiber to be fused and cut it. The cutting length does not exceed the excess cavity length. Repeat steps (2) and (3) in a small number of multiple cuttings until the excess cavity length is reduced to the mm level.

[0014] (4) Fusing the end faces of the first polarization-maintaining fiber and the second polarization-maintaining fiber to be fused, continuing to calculate the excess cavity length using the method of step (2), and using a fiber grinder to grind the FC / PC head in small amounts and multiple times until the excess cavity length cannot be resolved by OFDR;

[0015] (5) A multilayer Bragg reflection film is plated on the polished FC / PC head to obtain a fully polarization-maintaining fiber-mode-locked laser cavity.

[0016] Furthermore, the full polarization-maintaining fiber amplifier includes a fiber coupler and a polarization-maintaining erbium-doped fiber. The two input ends of the fiber coupler are respectively connected to the FC / PC head of the full polarization-maintaining fiber mode-locked laser cavity and the external pump laser. The output end of the fiber coupler is connected to the polarization-maintaining erbium-doped fiber. The output end of the polarization-maintaining erbium-doped fiber is provided with an FC / APC head.

[0017] Furthermore, the polarization-maintaining erbium-doped optical fiber includes a first polarization-maintaining gain optical fiber and a second polarization-maintaining gain optical fiber with different dispersions.

[0018] Furthermore, the integrated dual-comb electronic control system includes a single-chip digital control module, a first amplifier, a second amplifier, a first repetition rate controller, a second repetition rate controller and a miniaturized external clock source;

[0019] The first repetition frequency controller and the second repetition frequency controller are used to control the cavity length of the local optical frequency comb and the signal optical frequency comb respectively. The output ends of the local optical frequency comb and the signal optical frequency comb, as well as the miniaturized external clock source, are respectively connected to the single-chip computer numerical control module. The two-way repetition frequency analog signals output by the local optical frequency comb and the signal optical frequency comb are converted into digital signals in the single-chip computer numerical control module. The miniaturized external clock source is used as the system clock reference source to generate a target repetition frequency control signal. The frequency difference between the two-way repetition frequency analog signals and the target repetition frequency control signal is calculated respectively. According to the frequency difference, a voltage signal for controlling the repetition frequency of the local optical frequency comb and the signal optical frequency comb is generated, and the two voltage signals are converted into two analog signals for output. Preferably, a beam splitter is installed at the output ends of the local optical frequency comb and the signal optical frequency comb, one end of the beam splitter is connected to the single-chip computer numerical control module for realizing the control part, and the other end of the beam splitter outputs an optical frequency comb for realizing dual-comb time-of-flight ranging.

[0020] The two analog signals are amplified by the first amplifier and the second amplifier respectively and then transmitted to the first repetition rate controller and the second repetition rate controller.

[0021] Furthermore, it also includes two analog signal mixing circuits, each of which includes a detector, a filter, a third amplifier, a frequency divider, a mixer and a filter connected in series in sequence, and the miniaturized external clock source is respectively connected to the mixer;

[0022] The detectors in the two-channel analog signal mixing circuit detect the repetition frequency analog signals of the local optical frequency comb and the signal optical frequency comb respectively. After filtering, power amplification, and frequency division operations, they are mixed and filtered with a miniaturized external clock source to obtain two lower-frequency repetition frequency down-conversion signals. The two repetition frequency down-conversion signals are connected to the single-chip microcomputer numerical control module to replace the two repetition frequency analog signals.

[0023] Furthermore, the single-chip microcomputer numerical control module includes a DDS and two numerical control circuits, each of which includes an ADC, a phase detector, a feedback controller and a DAC connected in series; the DDS generates the two target repetition rate control signals through the miniaturized external clock source; the phase detector calculates the difference between the two lower-frequency repetition rate down-conversion signals and the target repetition rate control signal, and generates a voltage signal for controlling the repetition rate of the local optical frequency comb and the signal optical frequency comb through the feedback controller.

[0024] Furthermore, the miniaturized external clock source adopts a miniaturized rubidium clock chip.

[0025] Furthermore, it also includes a power drive module for supplying power to the first repetition frequency controller, the second repetition frequency controller, the first amplifier, the second amplifier, the miniaturized external clock source, the single-chip computer numerical control module, and the two-channel analog signal mixing circuit.

[0026] Compared with the existing dual-comb system, the characteristics and advantages of the present invention are:

[0027] (1) The optical system of the dual-comb system proposed in the present invention adopts a fully polarization-maintaining fiber structure design, which saves the volume of the optical system to the maximum extent. At the same time, the high environmental stability of the polarization-maintaining fiber can be utilized to improve the overall environmental stability of the dual-comb system, which is beneficial for its application in actual ranging scenarios.

[0028] (2) Through precise fiber cavity length control technology and multi-layer Bragg coating technology, a fully polarization-maintaining fiber dual-comb system with slightly different repetition rates is produced to meet the needs of dual-comb ranging. By first controlling the fiber cavity length and then performing cavity locking, the number of fiber splicing and cutting can be minimized, reducing the failure rate of cavity formation.

[0029] (3) Through the integration of the dual-comb electronic control system, the performance requirements for hardware are reduced, the size of the electronic control system is compressed, the power consumption is reduced, and the miniaturization and practical application of the dual-comb system are promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are merely embodiments of the present application and should not be regarded as limiting the scope. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 Schematic diagram of the optical system of the dual-comb system in the embodiment of the present application;

[0032] Figure 2 Schematic diagram of the electrical control system of the dual optical comb system in an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the application objectives, features, and advantages of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0034] See also Figure 1 The present invention provides a miniaturized fully polarization-maintaining fiber dual-comb system, which includes a miniaturized fully polarization-maintaining fiber dual-comb optical system and an integrated dual-comb electronic control system. The miniaturized fully polarization-maintaining fiber dual-comb optical system includes a fully polarization-maintaining fiber mode-locked laser cavity for a local optical frequency comb and a signal optical frequency comb, and a fully polarization-maintaining fiber amplifier. The fully polarization-maintaining fiber mode-locked laser cavity is prepared by using a fiber cavity length precision control technology and a multi-layer Bragg coating technology. Under the control of the integrated dual-comb electronic control system, a dual-comb with slightly different repetition frequencies (repetition frequency difference on the order of kHz) is generated, which is used for dual-comb time-of-flight ranging.

[0035] In one embodiment of the present application, the fully polarization-maintaining fiber-mode-locked laser cavity for both the local optical frequency comb and the signal optical frequency comb utilizes a fully polarization-maintaining linear fiber laser cavity based on semiconductor saturable absorber (SESAM) mode locking. This is achieved through a SESAM device encapsulated in a microfiber structure, offering the advantages of easy mode locking, compact size, and full polarization maintenance. The linear fiber laser cavity utilizes a SESAM as a reflective surface at one end, and an FC / PC head coated with a multilayer Bragg reflector film as an output mirror at the other end. When preparing the fully polarization-maintaining fiber-mode-locked laser cavity, two optical fiber segments are fused together to form a cavity. The fully polarization-maintaining fiber-mode-locked laser cavity comprises a first optical fiber and a second optical fiber. One end of the first optical fiber utilizes a semiconductor saturable absorber as a reflective surface, and one end of the first optical fiber utilizes an FC / PC head coated with a multilayer Bragg reflector film as an output mirror. The other end of the first optical fiber is fused to the other end of the second optical fiber, and one end of the first optical fiber is used to connect to an external pump laser. This design minimizes the use of intracavity components, facilitates miniaturization of the laser cavity, and facilitates subsequent precise control of the fiber cavity length.

[0036] The implementation methods of optical fiber cavity length precision control technology include:

[0037] (1) Before fiber fusion splicing and FC / PC head coating and cavity formation, a slightly longer fiber should be reserved according to the design to facilitate subsequent removal;

[0038] (2) Place the fiber end faces to be spliced ​​on a fiber fusion splicer and align them. Before the final splicing operation, use an optical frequency domain reflectometer (OFDR) to connect the FC / PC head and measure the time difference between the reflection of the probe light at the FC / PC head and the reflection at the SESAM end, and then calculate the fiber cavity length at this time.

[0039] (3) Remove any fiber end face and cut it, ensuring that the cut length does not exceed the current length that exceeds the target cavity length. Cut it in small quantities and multiple times and continue measuring with OFDR.

[0040] (4) When the fiber end face cannot be cut manually (it still exceeds the target cavity length, usually in mm), the two fiber end faces are fused together and the cavity length is continued to be measured using OFDR.

[0041] (5) Use the current excess length as the set value and use the fiber grinder to grind the FC / PC head. At this time, you can also set a value slightly lower than the excess length as the set value, perform small amounts of grinding multiple times, and continue to use OFDR to measure the cavity length, and continuously grind the fiber cavity to the target length.

[0042] With the current measurement resolution of OFDR and fiber grinders, precise control of the fiber cavity length at the μm level can be achieved. Within the length range of the cavity length adjustment of the repetition rate controller, the expected dual-comb repetition rate difference can be achieved through subsequent adjustment of the cavity length of the repetition rate controller.

[0043] Multi-layer Bragg coating technology, after the dual-comb cavity length is controlled within the μm range, a multi-layer Bragg reflector film is coated on the FC / PC head to achieve stable transmittance and reflectivity within the optical spectrum of the optical comb output band, thereby obtaining a fully polarization-maintaining fiber-mode-locked laser cavity for the local optical frequency comb / signal optical frequency comb.

[0044] The fiber cavity length precision control technology and multi-layer Bragg coating technology can realize the cavity length control of the mode-locked laser cavity based on only one fiber cavity fusion, avoiding the problem of over-cutting and needing to re-fusion-fuse the fiber when cutting the fusion welds multiple times.

[0045] In one embodiment of the present application, a fully polarized-maintaining fiber amplifier employs a fully polarized-maintaining fiber structure, including a fiber coupler, a first polarization-maintaining erbium-doped fiber, and a second polarization-maintaining erbium-doped fiber. The two input ends of the fiber coupler are connected to the FC / PC head of the fully polarized-maintaining fiber mode-locked laser cavity and an external pump laser, respectively. The output end of the fiber coupler is sequentially connected to the first polarization-maintaining erbium-doped fiber and the second polarization-maintaining erbium-doped fiber. The output end of the second polarization-maintaining erbium-doped fiber is provided with an FC / APC head. The first polarization-maintaining erbium-doped fiber and the second polarization-maintaining erbium-doped fiber can utilize polarization-maintaining gain fibers with different dispersions to regulate the dispersion of the optical frequency comb, compress the output pulse width of the dual-comb system, and improve the ranging accuracy of the time-of-flight method.

[0046] See also Figure 2 The integrated dual-comb electronic control system mainly includes a pair of repetition frequency controllers, a pair of amplifiers, a miniaturized external clock source, two-way analog signal mixing circuits, a single-chip digital control module, and a power drive module.

[0047] In one embodiment of the present application, the miniaturized external clock source uses a miniaturized rubidium clock chip.

[0048] In one embodiment of the present application, each analog signal mixing circuit includes a detector, a filter, a third amplifier, a divider, a mixer and a filter connected in series in sequence, and the miniaturized external clock source is connected to the mixer respectively; in the two analog signal mixing circuits, two high-speed detectors are used to detect the repetition analog signals of the local optical frequency comb and the signal optical frequency comb respectively, and after filtering, power amplification, frequency division and other operations, they are mixed and filtered with the miniaturized external clock source to obtain two lower-frequency repetition down-conversion signals.

[0049] In one embodiment of the present application, each component in the analog signal mixing circuit adopts a miniaturized integrated analog signal processing chip to minimize the volume.

[0050] In one embodiment of the present application, a single-chip microcomputer numerical control module includes a direct digital frequency synthesizer (DDS) and two numerical control circuits, each of which includes a serially connected analog-to-digital converter (ADC), a phase detector, a feedback controller, and a digital-to-analog converter (DAC). The miniaturized external clock source is connected to the phase detector via the DDS. The repetition frequency down-conversion signal is converted into a digital signal by the ADC and digital phase detection is performed in the single-chip microcomputer phase detector module to obtain the frequency difference between the repetition frequency down-conversion signal and the target repetition frequency control signal. The feedback controller then generates a voltage signal for controlling the repetition frequency of the local optical frequency comb and the signal optical frequency comb, which is converted into an analog signal and output by the DAC. The target repetition frequency control signal is generated in the internal digital DDS by the single-chip microcomputer numerical control module using the miniaturized external clock as the system clock reference source.

[0051] In one embodiment of the present application, the feedback controller may adopt a dynamic PID controller or a Kalman filter whose control parameters can be dynamically adjusted.

[0052] In one embodiment of this application, a single-chip digital control module can directly convert the repetition frequency signals of the local optical frequency comb and the signal optical frequency comb into digital signals for processing, eliminating the analog signal mixing circuit and achieving a more compact electronic control system. However, this approach places extremely high demands on the computing speed of the single-chip digital control chip and the sampling rate of the ADC, making it an alternative solution for electronic control systems.

[0053] The analog signal output by the single-chip computer numerical control module is amplified by the amplifier and transmitted to the repetition frequency controller used to control the cavity length of the local optical frequency comb and the signal optical frequency comb.

[0054] The power driver module is used to realize the current drive of the pump laser of the local optical frequency comb and the signal optical frequency comb, the pump laser current drive of the full polarization-maintaining fiber amplifier, the power drive of the single-chip computer numerical control module, the power drive of the analog signal mixing circuit, etc. According to the power parameter requirements of each module, reasonable power drive integration is carried out to achieve the miniaturization of the power driver module.

[0055] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0056] The above is a description of the miniaturized fully polarization-maintaining optical fiber dual-comb system provided by the present application. For those skilled in the art, based on the concepts of the embodiments of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A miniaturized fully polarization-maintaining fiber dual-comb system for dual-comb time-of-flight ranging, characterized by: The dual-comb system includes a full polarization-maintaining fiber dual-comb optical system and an integrated dual-comb electronic control system; The full-polarization-maintaining fiber dual-comb optical system is composed of a local optical frequency comb and a signal optical frequency comb. The local optical frequency comb and the signal optical frequency comb each include a full-polarization-maintaining fiber mode-locked laser cavity and a full-polarization-maintaining fiber amplifier. The full-polarization-maintaining fiber amplifier is connected to the full-polarization-maintaining fiber mode-locked laser cavity. The full-polarization-maintaining fiber mode-locked laser cavity is manufactured using fiber cavity length precision control technology and multi-layer Bragg coating technology. The integrated dual-comb electronic control system is used to control the cavity length of the full-polarization-maintaining fiber mode-locked laser cavity in the full-polarization-maintaining fiber dual-comb optical system, so as to generate a dual-comb with a repetition frequency difference of the kilohertz level; The fully polarization-maintaining fiber mode-locked laser cavity comprises a first polarization-maintaining fiber and a second polarization-maintaining fiber. One end of the first polarization-maintaining fiber uses a semiconductor saturable absorber SESAM as a reflection surface, and one end of the second polarization-maintaining fiber uses an FC / PC head coated with a multilayer Bragg reflection film as an output mirror. The other end of the first polarization-maintaining fiber is fused with the other end of the second polarization-maintaining fiber. The fiber cavity length precision control technology and the multilayer Bragg coating technology include: (1) preparing a first polarization-maintaining fiber and a second polarization-maintaining fiber, wherein the lengths of the first polarization-maintaining fiber and the second polarization-maintaining fiber exceed the length of the target cavity, one end of the second polarization-maintaining fiber is connected to an original FC / PC head, the original FC / PC head is not coated with a multilayer Bragg reflection film, and one end of the first polarization-maintaining fiber is focused onto the SESAM surface through a micro-encapsulation structure; (2) Place the fiber end faces of the first polarization-maintaining fiber and the second polarization-maintaining fiber to be fused in a fiber fusion splicer and align them. Connect the original FC / PC head to the optical frequency domain reflectometer (OFDR). Measure the time difference between the reflection of the probe light at the FC / PC head and the reflection at the SESAM end to obtain the fiber cavity length. Calculate the excess cavity length based on the target cavity length and the measured fiber cavity length. (3) Take out the fiber end face of any polarization-maintaining fiber to be fused and cut it. The cutting length does not exceed the excess cavity length. Repeat steps (2) and (3) in a small number of multiple cuttings until the excess cavity length is reduced to the mm level. (4) Fuse the end faces of the first polarization-maintaining fiber and the second polarization-maintaining fiber to be fused, continue to calculate the excess cavity length using the method in step (2), and use a fiber grinder to grind the FC / PC head in small amounts and multiple times until the excess cavity length cannot be resolved by OFDR; (5) A multilayer Bragg reflection film is coated on the polished FC / PC head to obtain a fully polarization-maintaining fiber-mode-locked laser cavity.

2. The miniaturized full polarization-maintaining fiber dual-comb system according to claim 1, characterized in that: The full polarization-maintaining fiber amplifier includes a fiber coupler and a polarization-maintaining erbium-doped fiber. The two input ends of the fiber coupler are respectively connected to the FC / PC head of the full polarization-maintaining fiber mode-locked laser cavity and the external pump laser. The output end of the fiber coupler is connected to the polarization-maintaining erbium-doped fiber. The output end of the polarization-maintaining erbium-doped fiber is provided with an FC / APC head.

3. The miniaturized full polarization-maintaining fiber dual-comb system according to claim 2, characterized in that: The polarization-maintaining erbium-doped optical fiber includes a first polarization-maintaining gain optical fiber and a second polarization-maintaining gain optical fiber using different dispersions.

4. The miniaturized full polarization-maintaining fiber dual-comb system according to claim 1, characterized in that: The integrated dual-comb electronic control system includes a single-chip digital control module, a first amplifier, a second amplifier, a first repetition frequency controller, a second repetition frequency controller and a miniaturized external clock source; The first repetition frequency controller and the second repetition frequency controller are used to control the cavity lengths of the local optical frequency comb and the signal optical frequency comb, respectively. The output ends of the local optical frequency comb and the signal optical frequency comb, as well as the miniaturized external clock source, are respectively connected to a single-chip microcomputer numerical control module. The two repetition frequency analog signals output by the local optical frequency comb and the signal optical frequency comb are converted into digital signals within the single-chip microcomputer numerical control module. The miniaturized external clock source is used as a system clock reference source to generate a target repetition frequency control signal. The frequency difference between the two repetition frequency analog signals and the target repetition frequency control signal is calculated, and a voltage signal for controlling the repetition frequency of the local optical frequency comb and the signal optical frequency comb is generated according to the frequency difference. The two voltage signals are converted into two analog signals for output; The two analog signals are amplified by the first amplifier and the second amplifier respectively and then transmitted to the first repetition rate controller and the second repetition rate controller.

5. The miniaturized full polarization-maintaining fiber dual-comb system according to claim 4, characterized in that: It also includes two analog signal mixing circuits, each of which includes a detector, a filter, a third amplifier, a frequency divider, a mixer and a filter connected in series, and the miniaturized external clock source is connected to the mixer respectively; The detectors in the two-channel analog signal mixing circuit detect the repetition frequency analog signals of the local optical frequency comb and the signal optical frequency comb respectively. After filtering, power amplification, and frequency division operations, they are mixed and filtered with a miniaturized external clock source to obtain two lower-frequency repetition frequency down-conversion signals. The two repetition frequency down-conversion signals are connected to the single-chip microcomputer numerical control module to replace the two repetition frequency analog signals.

6. The miniaturized full polarization-maintaining fiber dual-comb system according to claim 4 or 5, characterized in that: The single-chip microcomputer numerical control module includes a DDS and two numerical control circuits, each of which includes an ADC, a phase detector, a feedback controller and a DAC connected in series; the DDS generates the two target repetition rate control signals through the miniaturized external clock source; the phase detector calculates the difference between the two lower-frequency repetition rate down-conversion signals and the target repetition rate control signal, and generates a voltage signal for controlling the repetition rate of the local optical frequency comb and the signal optical frequency comb through the feedback controller.

7. The miniaturized full polarization-maintaining fiber dual-comb system according to claim 4, characterized in that: The miniaturized external clock source adopts a miniaturized rubidium clock chip.

8. The miniaturized full polarization-maintaining fiber dual-comb system according to claim 4, characterized in that: It also includes a power drive module for supplying power to the first repetition frequency controller, the second repetition frequency controller, the first amplifier, the second amplifier, a miniaturized external clock source, a single-chip computer numerical control module, and a two-channel analog signal mixing circuit.

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