Wavelength and repetition frequency independent adjustable gain-competition-free polarization-maintaining optical fiber common-cavity double-optical-comb mode-locked laser and adjusting method

Abstract

The invention discloses a wavelength and repetition frequency independent adjustable gain-competition-free polarization-maintaining fiber common-cavity double-optical-comb mode-locked laser and an adjusting method, and relates to the technical field of optical frequency combs. In order to solve the problems that a system is easily influenced by an external environment, the anti-interference capability is poor and gain competition exists between optical combs due to the existence of a single-mode optical fiber in an existing optical fiber double-optical-comb structure, the invention provides an optical fiber double-optical-comb structure. According to the technical scheme, the laser comprises a polarization-maintaining pump laser, a first polarization-maintaining optical fiber coupler, a polarization-maintaining optical fiber wavelength division multiplexer, a polarization-maintaining ytterbium-doped optical fiber, a polarization-maintaining collimator and a blazed grating, laser output by a second polarization-maintaining optical fiber coupler is combined through a polarization-maintaining polarization beam combiner, and the polarization-maintaining polarization beam combiner serves as a horizontal polarizer and a vertical polarizer; the separated polarized laser is respectively coupled to a slow axis and a fast axis of a common-end tail fiber, and a semiconductor saturable absorber is used as a reflection end face. According to the invention, a full polarization-maintaining structure is adopted, the external environment resistance is strong, and the stability is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical frequency combs, and particularly to a polarization-maintaining fiber common-cavity dual-comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition. Background Art

[0002] An optical frequency comb is a light source with extremely high precision. Its rapid development in recent years has provided strong support for many high-tech applications, such as high-resolution spectroscopy, metrology, and astronomy. In recent years, a method for generating dual optical frequency combs with a single-cavity mode-locked laser has attracted much attention. Two sets of femtosecond pulses with slightly different repetition frequencies can be generated in the same laser. The free-running single-cavity dual-comb laser has a common-mode noise suppression effect due to the common cavity. The relative frequency stability and coherence between the generated pulses are high. Therefore, there is no need for active control such as frequency locking of the laser cavity, which significantly reduces the complexity and cost of the dual-comb light source and has the potential to replace the traditional large and expensive frequency-locked dual-optical frequency comb system. Although the single-cavity dual-comb mode-locked laser has advantages such as simple structure and low cost, its development time is short, and there are still disadvantages such as poor resistance to the external environment and difficulty in flexibly adjusting the repetition frequency and the difference in repetition frequencies. In addition, the dual-comb spectroscopy detection technology has emerged in the field of measuring fast dynamic processes and has become a new research trend and development tendency. A wavelength-tunable dual-comb light source can flexibly adjust the spectral bandwidth and detection range while maintaining a high update speed, thus overcoming the technical bottleneck in traditional dual-comb spectroscopy to a certain extent. It is beneficial for high-speed measurement and multi-scene switching in engineering applications. Therefore, how to improve stability and achieve flexible adjustment of wavelength and repetition frequency is one of the research directions for future dual optical frequency combs. Summary of the Invention

[0003] The purpose of the present invention is to provide a polarization-maintaining fiber common-cavity dual-comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition and an adjustment method, so as to solve the problems that in the existing fiber dual-comb structure, due to the existence of single-mode fibers, the system is easily affected by the external environment, has poor anti-interference ability, and there is gain competition between the optical frequency combs.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: A polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition, comprising: a polarization-maintaining pump laser, the output end of the polarization-maintaining pump laser is connected to a first polarization-maintaining fiber coupler, the first polarization-maintaining fiber coupler is connected to two polarization-maintaining fiber wavelength division multiplexers, one end of each polarization-maintaining fiber wavelength division multiplexer is sequentially provided with a polarization-maintaining ytterbium-doped fiber, a polarization-maintaining collimator and a blazed grating, the other end of each polarization-maintaining fiber wavelength division multiplexer is provided with a second polarization-maintaining fiber coupler, the laser output by the second polarization-maintaining fiber coupler is combined by a polarization-maintaining polarization beam combiner, the polarization-maintaining polarization beam combiner serves as a horizontal polarizer and a vertical polarizer, and separates the polarized laser into the slow axis and the fast axis of the common-end fiber respectively, and the right side of the polarization-maintaining polarization beam combiner uses a semiconductor saturable absorber as a reflection end face.

[0005] Preferably, a lens for focusing the beam is provided between the polarization-maintaining collimator and the blazed grating.

[0006] Preferably, the optical signal power distribution ratio of the first polarization-maintaining fiber coupler is 50:50.

[0007] Preferably, the optical signal power distribution ratio of the second polarization-maintaining fiber coupler is 80:20.

[0008] An adjustment method for a polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition, comprising the following steps: S1. Pump light separation and gain medium excitation: using the first polarization-maintaining fiber coupler to separate the pump light from the polarization-maintaining pump laser; guiding the separated pump light to two polarization-maintaining ytterbium-doped fibers respectively through the polarization-maintaining fiber wavelength division multiplexer; in the polarization-maintaining ytterbium-doped fiber, the pump light excites the gain medium to generate stimulated emission light.

[0009] S2. Orthogonal polarized light generation and transmission: using the polarization-maintaining polarization beam combiner to separate the stimulated emission light into horizontally polarized light and vertically polarized light; making the two orthogonal polarized lights perform common-cavity transmission along the slow axis and the fast axis of the polarization-maintaining fiber respectively.

[0010] S3. Independent wavelength adjustment: setting a blazed grating as the reflection end face in the laser cavity, using the blazed grating to reflect the first-order diffracted light back into the cavity; adjusting the filtering bandwidth by controlling the distance between the blazed grating and the polarization-maintaining collimator; adjusting the angle of the blazed grating to achieve independent tunability of the central wavelength of the output laser.

[0011] S4. Repetition frequency and repetition frequency difference adjustment: changing the distance between the lens and the polarization-maintaining collimator to independently adjust the repetition frequencies of different polarization states; realizing the adjustment of the repetition frequency difference by precisely controlling the spatial length difference between the two laser cavities; ensuring the stability of the mode-locked state during the adjustment process.

[0012] S5, Mode-locked Laser Output and Optical Signal Distribution: Using a semiconductor saturable absorber as one of the mode-locking devices and the end mirror of the laser cavity, and jointly realizing cavity closure with a blazed grating; outputting two beams of mode-locked lasers with orthogonal polarization states through the output port of the second polarization-maintaining fiber coupler; distributing or combining the optical signal power at the output port as needed.

[0013] Preferably, in step S3, it further includes: precisely controlling the angle of the blazed grating by using a piezoelectric ceramic driving device to achieve high-precision and fast response for wavelength adjustment; setting up a wavelength locking circuit to ensure the stability and accuracy of the output wavelength by monitoring the wavelength of the output laser and feeding back to the piezoelectric ceramic driving device; introducing a tunable filter into the laser cavity to work together with the blazed grating to expand the wavelength adjustment range and increase the flexibility of wavelength adjustment.

[0014] Preferably, in step S4, it further includes: setting up a laser cavity mirror mount with adjustable length to adjust the cavity lengths of the two laser cavities without disassembling the laser cavity, thereby adjusting the repetition frequency; using a high-precision displacement sensor to monitor the change in cavity length to ensure the accuracy of repetition frequency adjustment; introducing an optical delay line to finely adjust the spatial length difference between the two laser cavities by adjusting the length of the delay line to achieve precise adjustment of the small range of repetition frequency difference.

[0015] Preferably, in step S5, it further includes: the second polarization-maintaining fiber coupler uses a polarization-maintaining fiber beam splitter to improve the polarization maintaining performance and signal-to-noise ratio of the output laser; setting up an optical power stabilizer to ensure the stability and consistency of the optical signal by monitoring and adjusting the power of the output laser; introducing an optical switch or an optical modulator to dynamically distribute or modulate the optical signal at the output port according to application requirements.

[0016] The present invention has the following beneficial effects: The present invention adopts a fully polarization-maintaining structure, has strong resistance to the external environment, and greatly improves its stability; by sharing a single pump laser source, the influence of pump noise in the cavity is reduced, and the noise within the system is lowered; using a Y-shaped cavity to pump two gain media separately to eliminate the gain competition between the two beams; by controlling the distances between two different gratings and collimators to control the filtering bandwidth and repetition frequency, adjusting the grating angle can achieve tunability of the central wavelength of the output laser, thereby enabling independent adjustment of the central wavelengths of the optical frequency combs in different polarization directions; by adjusting the distance between the lens and the collimator, the repetition frequencies of different polarization states can be independently adjusted, thereby achieving adjustment of the repetition frequency difference.

[0017] Compared with the laser structure with non-separated gain, the present invention can avoid problems such as in-cavity gain competition and pulse collision, and this solution has the characteristics of high mutual coherence, high stability, and independently flexible tunability of wavelength and repetition frequency. Description of the Drawings

[0018] Figure 1 This is a schematic structural diagram of a polarization-maintaining fiber common-cavity dual-comb mode-locked laser with independently tunable wavelength and repetition frequency and no gain competition according to the present invention; Figure 2 This is the schematic diagram of Embodiment 2 of the present invention; Figures 1 to 2 The reference numerals shown in the figure are respectively represented as: polarization-maintaining pump laser 1, first polarization-maintaining fiber coupler 21, second polarization-maintaining fiber coupler 22, polarization-maintaining fiber wavelength division multiplexer 3, polarization-maintaining ytterbium-doped fiber 4, polarization-maintaining collimator 5, blazed grating 6, polarization-maintaining polarization beam combiner 7, slow axis 71, fast axis 72, semiconductor saturable absorber 8, and lens 9. Detailed implementation manners

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0020] Embodiment 1 Please refer to Figure 1 , the present invention relates to a polarization-maintaining fiber common-cavity dual-comb mode-locked laser with independently tunable wavelength and repetition frequency and no gain competition, aiming to provide a dual-comb mode-locked laser with high stability, high mutual coherence, and independently and flexibly tunable wavelength and repetition frequency. The following will elaborate on the specific implementation manners of the present invention in detail.

[0021] First of all, the polarization-maintaining fiber common-cavity dual-comb mode-locked laser designed by the present invention mainly includes the following components: a polarization-maintaining pump laser 1, a first polarization-maintaining fiber coupler 21, two polarization-maintaining fiber wavelength division multiplexers 3, two sections of polarization-maintaining ytterbium-doped fiber 4, two polarization-maintaining collimators 5, two blazed gratings 6, two lenses 9, two second polarization-maintaining fiber couplers 22, a polarization-maintaining polarization beam combiner 7, and a semiconductor saturable absorber 8.

[0022] The polarization-maintaining pump laser 1, as the light source for exciting the gain medium, has its output end connected to the first polarization-maintaining fiber coupler 21. In this embodiment, the first polarization-maintaining fiber coupler 21 adopts a 50:50 optical signal power distribution ratio to equally separate the pump light from the polarization-maintaining pump laser 1 into two beams. This distribution ratio ensures that the two gain media (i.e., the two sections of polarization-maintaining ytterbium-doped fiber 4) can obtain equal pump power, thus avoiding the problem of gain competition.

[0023] The two separated pump beams are respectively guided into two segments of polarization-maintaining ytterbium-doped fibers 4 through two polarization-maintaining fiber wavelength division multiplexers 3. The polarization-maintaining fiber wavelength division multiplexer 3 allows two wavelength signals to be transmitted simultaneously in the same fiber, reflects the 976 nm pump light, and transmits the 1030 nm stimulated radiation light. In the polarization-maintaining ytterbium-doped fiber 4, the pump light excites the gain medium to generate stimulated radiation light, thereby forming a laser.

[0024] Next, the output end of each segment of polarization-maintaining ytterbium-doped fiber 4 is connected to a polarization-maintaining collimator 5 for collimating the output beam. A lens 9 is provided between the polarization-maintaining collimator 5 and the blazed grating 6 for focusing the beam. The blazed grating 6 serves as the reflecting end face, and the first-order diffracted light is reflected back into the cavity by using the Littrow structure of the blazed grating. In the Littrow structure, there is a blaze angle between the groove plane of the reflecting grating and the grating plane. When the incident light is incident on the grating at a specific angle (i.e., the blaze angle), the diffracted light will return along the direction of the incident light at the same angle. By controlling the distance between the blazed grating 6 and the polarization-maintaining collimator 5, the filtering bandwidth can be adjusted, thereby affecting the wavelength characteristics of the laser. At the same time, by adjusting the angle of the blazed grating 6, the center wavelength of the output laser can be independently adjusted.

[0025] Two second polarization-maintaining fiber couplers 22 are respectively connected to the other ends of the two polarization-maintaining fiber wavelength division multiplexers 3 for outputting the laser. These second polarization-maintaining fiber couplers 22 adopt an 80:20 optical signal power distribution ratio to distribute or combine the optical signal power at the output port to meet different application requirements.

[0026] The two output laser beams are combined by a polarization-maintaining polarization beam combiner 7. The polarization-maintaining polarization beam combiner 7 serves as a horizontal polarizer and a vertical polarizer, and couples the separated polarized lasers to the slow axis 71 and the fast axis 72 of the common-end fiber respectively. In this way, after the signal laser oscillates multiple times in the oscillator, it will split into two laser beams with orthogonal polarizations and completely independent of each other, and each laser beam will form its own mode-locked pulse train. Conversely, when the signal laser returns from the right common end, the polarization-maintaining polarization beam combiner 7 acts as a polarization-maintaining polarization beam splitter, splitting the signal laser into horizontal polarization and vertical polarization, and coupling them to the corresponding tail fibers respectively.

[0027] On the right side of the polarization-maintaining polarization beam combiner 7, a semiconductor saturable absorber 8 is used as the reflecting end face to jointly achieve cavity closure with the blazed grating 6, thereby outputting stable mode-locked laser. The semiconductor saturable absorber 8 serves as a mode-locking device, which can ensure the stability of the mode-locked state of the laser.

[0028] Embodiment 2 Referring to Figure 2 , in order to achieve independent adjustment of the wavelength and the repetition frequency, the present invention also proposes a specific adjustment method, including the following steps: Step S1: Pump light separation and gain medium excitation. The pump light from the polarization-maintaining pump laser 1 is separated by the first polarization-maintaining fiber coupler 21, and the separated pump light is respectively guided into two sections of polarization-maintaining ytterbium-doped fibers 4 through the polarization-maintaining fiber wavelength division multiplexer 3. In the polarization-maintaining ytterbium-doped fiber 4, the pump light excites the gain medium to generate stimulated emission light.

[0029] Step S2: Generation and transmission of orthogonally polarized light. The stimulated emission light is separated into horizontally polarized light and vertically polarized light by the polarization-maintaining polarization beam combiner 7, and the two orthogonally polarized lights are co-cavity transmitted along the slow axis 71 and the fast axis 72 of the polarization-maintaining fiber respectively. In this way, two lasers with orthogonal polarization and completely independent of each other oscillate in the cavity to form a mode-locked pulse train.

[0030] Step S3: Wavelength independent adjustment. A blazed grating 6 is set as the reflection end face in the laser cavity, and the first-order diffracted light is reflected back into the cavity by the blazed grating 6. By controlling the distance between the blazed grating 6 and the polarization-maintaining collimator 5, the filtering bandwidth is adjusted, thereby affecting the wavelength characteristics of the laser. At the same time, by adjusting the angle of the blazed grating 6, the center wavelength of the output laser can be independently adjusted. In this embodiment, a piezoelectric ceramic driving device is used to precisely control the angle of the blazed grating 6 to achieve high-precision and fast response of wavelength adjustment. In addition, a wavelength locking circuit can be set up to ensure the stability and accuracy of the output wavelength by monitoring the wavelength of the output laser and feeding back to the piezoelectric ceramic driving device. In order to further expand the wavelength adjustment range and increase the flexibility of wavelength adjustment, a tunable filter can also be introduced into the laser cavity to work in cooperation with the blazed grating 6.

[0031] Step S4: Repetition rate and repetition rate difference adjustment. The distance between the lens 9 and the polarization-maintaining collimator 5 is changed to independently adjust the repetition rates of different polarization states. By precisely controlling the spatial length difference between the two laser cavities (for example, by adjusting the adjustable length of the laser cavity mirror mount), the adjustment of the repetition rate difference can be achieved. In this embodiment, a high-precision displacement sensor is used to monitor the change of the cavity length to ensure the accuracy of the repetition rate adjustment. In addition, an optical delay line can be introduced to finely adjust the spatial length difference between the two laser cavities by adjusting the length of the delay line, thereby achieving a small-range precise adjustment of the repetition rate difference.

[0032] Step S5: Mode-locked laser output and optical signal distribution. Using the semiconductor saturable absorber 8 as one of the mode-locking devices and the laser cavity end mirror, it jointly realizes cavity closure with the blazed grating 6. Two beams of mode-locked lasers with orthogonal polarization states are output through the output port of the second polarization-maintaining fiber coupler 22. In this embodiment, the second polarization-maintaining fiber coupler 22 adopts a polarization-maintaining fiber beam splitter to improve the polarization-maintaining performance and signal-to-noise ratio of the output laser. At the same time, an optical power stabilizer can also be set to ensure the stability and consistency of the optical signal by monitoring and adjusting the power of the output laser. In addition, introducing an optical switch or an optical modulator can dynamically distribute or modulate the optical signal at the output port according to application requirements.

[0033] The advantages of the present invention are as follows: First, the use of a fully polarization-maintaining structure greatly improves the anti-external environment ability of the system, thus improving the stability; Second, by sharing a pump laser source and pumping two gain media respectively, the influence of pump noise in the cavity is reduced and the internal noise of the system is lowered; Third, the use of the Y-shaped cavity structure to pump two gain media respectively eliminates the gain competition between the two beams; In addition, by controlling the distances between two different gratings and collimators and adjusting the grating angles, the central wavelengths and repetition frequencies of the optical frequency combs in different polarization directions can be independently adjusted; Finally, the polarization-maintaining common cavity structure suppresses the common-mode noise, enabling the structure to obtain a stable and low-noise optical frequency comb.

[0034] In specific implementation, the present invention can also be further optimized and improved. For example, a higher-precision driving device and monitoring equipment can be adopted to improve the accuracy and stability of wavelength and repetition frequency adjustment; More optical elements and functional modules can also be introduced to expand the functions and performance of the system. These optimizations and improvements are all within the protection scope of the present invention.

[0035] In summary, the present invention provides a polarization-maintaining fiber common cavity dual optical frequency comb mode-locked laser with independently adjustable wavelength and repetition frequency and no gain competition and its adjustment method. The laser has the characteristics of high stability, high mutual coherence, and independently and flexibly adjustable wavelength and repetition frequency, and is suitable for various application scenarios that require high-precision and high-stability optical frequency combs.

[0036] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition, characterized in that, Comprising: A polarization-maintaining pump laser (1), the output end of the polarization-maintaining pump laser (1) is connected to a first polarization-maintaining fiber coupler (21), the first polarization-maintaining fiber coupler (21) is connected to two polarization-maintaining fiber wavelength division multiplexers (3), one end of each polarization-maintaining fiber wavelength division multiplexer (3) is sequentially provided with a polarization-maintaining ytterbium-doped fiber (4), a polarization-maintaining collimator (5) and a blazed grating (6), the other end of each polarization-maintaining fiber wavelength division multiplexer (3) is provided with a second polarization-maintaining fiber coupler (22), the laser output by the second polarization-maintaining fiber coupler (22) is combined by a polarization-maintaining polarization beam combiner (7), the polarization-maintaining polarization beam combiner (7) serves as a horizontal polarizer and a vertical polarizer, and separates the polarized laser light into the slow axis (71) and the fast axis (72) of the co-end fiber, and the right side of the polarization-maintaining polarization beam combiner (7) uses a semiconductor saturable absorber (8) as a reflection end face.

2. The polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition according to claim 1, wherein, A lens (9) for focusing the light beam is provided between the polarization-maintaining collimator (5) and the blazed grating (6).

3. The polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition according to claim 1, characterized in that The optical signal power distribution ratio of the first polarization-maintaining fiber coupler (21) is 50:

50.

4. The polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently tunable wavelength and repetition frequency and without gain competition according to claim 1, characterized in that, The optical signal power distribution ratio of the second polarization-maintaining fiber coupler (22) is 80:

20.

5. A method for adjusting a polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently adjustable wavelength and repetition frequency and without gain competition according to any one of claims 1 to 4, characterized in that, Including the following steps: S1. Pump light separation and gain medium excitation: Using the first polarization-maintaining fiber coupler (21) to separate the pump light from the polarization-maintaining pump laser (1); guiding the separated pump light to two polarization-maintaining ytterbium-doped fibers (4) through the polarization-maintaining fiber wavelength division multiplexer (3); in the polarization-maintaining ytterbium-doped fiber (4), the pump light excites the gain medium to generate stimulated emission light. S2. Orthogonal polarized light generation and transmission: Using the polarization-maintaining polarization beam combiner (7) to separate the stimulated emission light into horizontal linearly polarized light and vertical linearly polarized light; making the two orthogonal polarized lights co-cavity transmit along the slow axis (71) and the fast axis (72) of the polarization-maintaining fiber respectively. S3. Wavelength independent adjustment: Setting a blazed grating (6) as a reflection end face in the laser cavity, using the blazed grating (6) to reflect the first-order diffracted light back into the cavity; adjusting the filtering bandwidth by controlling the distance between the blazed grating (6) and the polarization-maintaining collimator (5); adjusting the angle of the blazed grating (6) to achieve independent adjustment of the central wavelength of the output laser. S4. Repetition frequency and repetition frequency difference adjustment: Changing the distance between the lens (9) and the polarization-maintaining collimator (5) to independently adjust the repetition frequencies of different polarization states; realizing the adjustment of the repetition frequency difference by precisely controlling the spatial length difference between the two laser cavities; ensuring the stability of the mode-locking state during the adjustment process. S5. Mode-locked laser output and optical signal distribution: Using the semiconductor saturable absorber (8) as one of the mode-locking devices and the laser cavity end mirror, and jointly realizing cavity closure with the blazed grating (6); outputting two beams of mode-locked lasers with orthogonal polarization states through the output port of the second polarization-maintaining fiber coupler (22); distributing or combining the optical signal power at the output port as needed.

6. The adjustment method of the polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently adjustable wavelength and repetition frequency and without gain competition according to claim 5, characterized in that In the step S3, it further includes: precisely controlling the angle of the blazed grating (6) by using a piezoelectric ceramic driving device to achieve high precision and fast response in wavelength adjustment; setting up a wavelength locking circuit to ensure the stability and accuracy of the output wavelength by monitoring the wavelength of the output laser and feeding back to the piezoelectric ceramic driving device; introducing a tunable filter into the laser cavity to work in cooperation with the blazed grating (6) to expand the wavelength adjustment range and increase the flexibility of wavelength adjustment.

7. The adjustment method of the polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently adjustable wavelength and repetition frequency and no gain competition according to claim 5, characterized in that, In the step S4, it further includes: setting up a laser cavity mirror mount with adjustable length to adjust the cavity lengths of the two laser cavities without disassembling the laser cavity, thereby adjusting the repetition frequency; using a high-precision displacement sensor to monitor the change in cavity length to ensure the accuracy of repetition frequency adjustment; introducing an optical delay line to finely adjust the spatial length difference between the two laser cavities by adjusting the length of the delay line to achieve precise adjustment of the repetition frequency difference within a small range.

8. The adjustment method of the polarization-maintaining fiber common-cavity dual optical comb mode-locked laser with independently adjustable wavelength and repetition frequency and no gain competition according to claim 5, characterized in that In the step S5, it further includes: the second polarization-maintaining fiber coupler (22) adopts a polarization-maintaining fiber beam splitter to improve the polarization maintaining performance and signal-to-noise ratio of the output laser; setting up an optical power stabilizer to ensure the stability and consistency of the optical signal by monitoring and adjusting the power of the output laser; introducing an optical switch or an optical modulator to dynamically allocate or modulate the optical signal at the output port according to application requirements.

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