A laser

Abstract

This application relates to the field of laser technology, specifically a laser comprising: a pump source, a half-wave plate assembly, a wavelength division multiplexer, a polarization-maintaining ytterbium-doped fiber, a first collimator, a first reflector, a second reflector, a first polarization beam splitter, a second polarization beam splitter, a first chirped fiber grating, and a narrow-linewidth fiber grating. The half-wave plate assembly is used to change the polarization direction of the laser, and the first and second reflectors are used to reflect P-polarized or S-polarized light to the half-wave plate assembly. The technical solution provided by this application enables the laser to output both femtosecond and picosecond lasers, reducing operating costs. Furthermore, the optical path design of this application is simple and highly compatible; by adjusting the half-wave plate assembly, the laser can switch between outputting different laser types. The femtosecond and picosecond laser outputs are stable, ensuring stable laser beam operation and improving the laser's performance.

Description

Technical Field

[0001] This application relates to the field of laser technology, and more specifically, to a laser. Background Technology

[0002] In recent years, with the rapid development of laser technology, lasers for various fields and scenarios have emerged. In some special applications, it is necessary to first use picosecond lasers for rough processing and then use femtosecond lasers for finishing. For these special laser applications, in most cases, two lasers are used and combined in the external optical path before being put into use, which leads to excessive costs. Integrated lasers have also been proposed, but integrated lasers are usually incompatible, and the design of the external optical path is extremely complex, making dimming difficult and prone to unstable operating results, affecting the performance.

[0003] Therefore, existing technology cannot meet our needs. Utility Model Content

[0004] The technical problem to be solved by the embodiments of this application is that the existing method of using two lasers is too costly, while integrated lasers are usually incompatible. At the same time, the design of the external optical path is extremely complex, the dimming is difficult, and the operation effect is unstable, which affects the use effect.

[0005] To address the aforementioned technical problems, this application provides a laser, employing the technical solution described below, including:

[0006] Pump source, used to generate a laser beam;

[0007] A wavelength division multiplexer is connected to the output of the pump source;

[0008] A polarization-maintaining ytterbium-doped fiber is connected to the wavelength division multiplexer to generate laser light.

[0009] The first collimator is connected to the polarization-maintaining ytterbium-doped fiber and is used to collimate the laser.

[0010] A half-wave plate assembly, connected to the first collimator, is used to change the polarization direction of the laser.

[0011] The first polarization beam splitter is connected to the half-wave plate assembly and is used to receive the laser light after its polarization direction has been changed, and to separate it into P-polarized light or S-polarized light.

[0012] The first reflector and the second reflector are respectively disposed on one side of the first polarization beam splitter, and are used to reflect P-polarized light or S-polarized light to the half-wave plate assembly.

[0013] The second polarization beam splitter, connected to the wavelength division multiplexer, is used to receive laser light that has been reflected by the first reflector or the second reflector to the half-wave plate assembly and then sequentially passes through the first collimator, the polarization-maintaining ytterbium-doped fiber and the wavelength division multiplexer.

[0014] The first chirped fiber grating is disposed on one side of the second polarization beam splitter to receive the P-polarized light separated by the second polarization beam splitter and to provide negative dispersion for the P-polarized light.

[0015] A narrow linewidth fiber grating is disposed on the other side of the second polarization beam splitter to receive the S-polarized light separated by the second polarization beam splitter and to filter the S-polarized light.

[0016] Wherein, the S-polarized light is either a femtosecond laser or a picosecond laser, and the P-polarized light is either a femtosecond laser or a picosecond laser. The pump source, half-wave plate assembly, wavelength division multiplexer, first reflector, first polarization beam splitter, polarization-maintaining ytterbium-doped fiber, first collimator, second polarization beam splitter, and first chirped fiber grating constitute a first resonant cavity for outputting femtosecond laser light. The pump source, half-wave plate assembly, wavelength division multiplexer, second reflector, first polarization beam splitter, polarization-maintaining ytterbium-doped fiber, first collimator, second polarization beam splitter, and narrow linewidth fiber grating constitute a second resonant cavity for outputting picosecond laser light.

[0017] Furthermore, the half-wave plate assembly includes a motor and a half-wave plate, the half-wave plate being disposed on the output end of the motor, and the motor being used to adjust the rotation angle of the half-wave plate.

[0018] Furthermore, the first reflector is selected from femtosecond semiconductor saturable absorber mirrors.

[0019] Furthermore, the second reflector is selected from picosecond semiconductor saturable absorber mirrors.

[0020] Furthermore, a first focusing lens is also provided between the first polarizing beam splitter and the first reflector.

[0021] Furthermore, a first focusing lens is also disposed between the first polarizing beam splitter and the second reflector.

[0022] Furthermore, the pump source is connected to the wavelength division multiplexer via a pump protector.

[0023] Furthermore, the laser also includes a third polarization beam splitter, wherein the second polarization beam splitter, the first chirped fiber grating, and the third polarization beam splitter are connected in sequence; and the second polarization beam splitter, the narrow linewidth fiber grating, and the third polarization beam splitter are connected in sequence.

[0024] Furthermore, the first resonant cavity also includes a circulator and a second chirped fiber grating, the circulator being disposed between the first chirped fiber grating and the third polarization beam splitter, and the second chirped fiber grating being connected to the circulator.

[0025] Furthermore, the laser also includes a second collimator connected to the third polarization beam splitter, and the femtosecond laser and the picosecond laser are output from the optical path end of the second collimator.

[0026] Compared with the prior art, the embodiments of this application have the following advantages: This application uses an integrated laser, eliminating the need for two lasers, enabling the laser to output both femtosecond and picosecond lasers, thus reducing usage costs. Furthermore, the optical path design of this application is simple and highly compatible; by adjusting the half-wave plate assembly, the laser can switch between outputting different lasers. The output of both the femtosecond and picosecond lasers is stable, ensuring stable laser beam operation and improving the laser's performance. Attached Figure Description

[0027] To more clearly illustrate the solution of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the laser structure in an embodiment of this application.

[0029] Reference numerals: 1. Pump source; 2. Half-wave plate assembly; 3. Wavelength division multiplexer; 4. First reflector; 5. Second reflector; 6. First polarization beam splitter; 7. First focusing lens; 8. Polarization-maintaining ytterbium-doped fiber; 9. First collimator; 11. Pump protector; 12. Second polarization beam splitter; 13. Third polarization beam splitter; 14. First chirped fiber grating; 15. Narrow linewidth fiber grating; 16. Circulator; 17. Second chirped fiber grating; 18. Second collimator. Detailed Implementation

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0032] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0033] Please see the appendix Figure 1 As shown, this application provides a laser.

[0034] Pump source 1 is used to generate a laser beam;

[0035] Wavelength division multiplexer 3 is connected to the output terminal of pump source 1;

[0036] A polarization-maintaining ytterbium-doped fiber 8 is connected to the wavelength division multiplexer 3 and is used to generate laser light.

[0037] The first collimator 9 is connected to the polarization-maintaining ytterbium-doped fiber 8 and is used to collimate the laser.

[0038] The half-wave plate assembly 2 is connected to the first collimator 9 and is used to change the polarization direction of the laser.

[0039] The first polarization beam splitter 6 is connected to the half-wave plate assembly 2 and is used to receive the laser after the polarization direction is changed, and to separate it into P-polarized light or S-polarized light.

[0040] The first reflector 4 and the second reflector 5 are respectively disposed on one side of the first polarization beam splitter 6, and are used to reflect P-polarized light or S-polarized light to the half-wave plate assembly 2.

[0041] The second polarization beam splitter 12 is connected to the wavelength division multiplexer 3 and is used to receive the laser light reflected by the first reflector 4 or the second reflector 5 to the half-wave plate assembly 2 and then passing through the first collimator 9, the polarization-maintaining ytterbium-doped fiber 8 and the wavelength division multiplexer 3 in sequence.

[0042] The first chirped fiber grating 14 is disposed on one side of the second polarization beam splitter 12, and is used to receive the P-polarized light separated by the second polarization beam splitter 12, and to provide negative dispersion for the P-polarized light.

[0043] A narrow linewidth fiber optic grating 15 is disposed on the other side of the second polarization beam splitter 12 to receive the S-polarized light separated by the second polarization beam splitter 12 and to filter the S-polarized light.

[0044] Wherein, the S-polarized light is either a femtosecond laser or a picosecond laser, and the P-polarized light is either a femtosecond laser or a picosecond laser. The pump source 1, the half-wave plate assembly 2, the wavelength division multiplexer 3, the first reflector 4, the first polarization beam splitter 6, the polarization-maintaining ytterbium-doped fiber 8, the first collimator 9, the second polarization beam splitter 12, and the first chirped fiber grating 14 constitute a first resonant cavity for outputting femtosecond laser light. The pump source 1, the half-wave plate assembly 2, the wavelength division multiplexer 3, the second reflector 5, the first polarization beam splitter 6, the polarization-maintaining ytterbium-doped fiber 8, the first collimator 9, the second polarization beam splitter 12, and the narrow linewidth fiber grating 15 constitute a second resonant cavity for outputting picosecond laser light.

[0045] In this application, the first polarization beam splitter 6 transmits P-polarized light and reflects S-polarized light. The first reflector 4 is disposed in the transmission optical path of the first polarization beam splitter 6 to receive and reflect P-polarized light, i.e., femtosecond laser light. The second reflector 5 is disposed in the reflection optical path of the first polarization beam splitter 6 to receive and reflect S-polarized light, i.e., picosecond laser light.

[0046] This application employs an integrated laser, eliminating the need for two separate lasers. This allows the laser to output both femtosecond and picosecond lasers, reducing operating costs. Furthermore, the optical path design of this application is simple and highly compatible. By adjusting the half-wave plate assembly 2, the laser can switch between outputting different lasers. The output of both the femtosecond and picosecond lasers is stable, ensuring stable laser operation and improving the laser's performance.

[0047] Furthermore, the femtosecond laser is output from the optical path end of the first resonant cavity, and the picosecond laser is output from the optical path end of the second resonant cavity.

[0048] Furthermore, the polarization-maintaining ytterbium-doped fiber 8 is disposed between the half-wave plate assembly 2 and the wavelength division multiplexer 3. The polarization-maintaining ytterbium-doped fiber 8 is used to generate laser light, improving the accuracy and efficiency of laser processing. When the first resonant cavity is operating, the polarization-maintaining ytterbium-doped fiber 8 generates femtosecond laser light; while when the second resonant cavity is operating, the polarization-maintaining ytterbium-doped fiber 8 generates picosecond laser light, achieving a stable laser mode and pulse output, thereby improving the stability and reliability of the laser.

[0049] Furthermore, the first collimator 9 is disposed between the half-wave plate assembly 2 and the polarization-maintaining ytterbium-doped fiber 8. The first collimator 9 can collimate the diverging beam into a parallel laser, ensuring a stable spot size and intensity distribution during propagation. This helps reduce wavefront distortion and improves the laser's quality and coherence. Simultaneously, the first collimator 9 can adjust the size and shape of the laser to better match the geometry and optical characteristics of the SESAM, improving the beam coupling efficiency on the SESAM and enhancing the SESAM's modulation effect on the beam, thereby achieving a more stable mode-locked state and a shorter pulse width.

[0050] Furthermore, the half-wave plate assembly 2 includes a motor and a half-wave plate. The half-wave plate is disposed on the output end of the motor, and the motor is used to adjust the rotation angle of the half-wave plate. By adjusting the rotation angle of the half-wave plate, the motor adjusts the angle between the fast axis of the wave plate and the incident polarization direction, thereby changing the polarization state of the laser to S-polarization or P-polarization, enabling dual pulse width switching. This simple structure and convenient switching simplify the optical path design, allowing the laser to switch between different laser outputs simply by adjusting the half-wave plate. P-polarized light is a femtosecond laser, and S-polarized light is a picosecond laser. The outputs of both the femtosecond and picosecond lasers are stable, ensuring stable laser operation and improving the laser's performance.

[0051] Furthermore, the first reflector 4 is selected from a femtosecond semiconductor saturable absorber mirror, and the second reflector 5 is selected from a picosecond semiconductor saturable absorber mirror. Semiconductor saturable absorber mirrors (SESAMs) can achieve mode-locking through the saturable absorption effect. Compared to passive mode-locking techniques such as nonlinear polarization rotation, semiconductor saturable absorber mirrors can automatically start and maintain mode-locking without external disturbance, simplifying laser operation. By adjusting the half-wave plate, the polarization state is matched with the semiconductor saturable absorber mirror, optimizing polarization control and achieving efficient mode-locking. Simultaneously, semiconductor saturable absorber mirrors offer stability and parameter flexibility.

[0052] Furthermore, a first focusing lens 7 is disposed between the first polarization beam splitter 6 and the first reflector 4, and also between the first polarization beam splitter 6 and the second reflector 5. The first focusing lens 7 can focus the laser light incident on the first reflector 4 and the second reflector 5 via the first polarization beam splitter 6, thereby increasing the power density of the light spot and obtaining a smaller light spot size. This results in a higher light intensity on the surface of the semiconductor saturable absorber mirror, allowing the laser light to pass through the semiconductor saturable absorber mirror more easily, thus achieving effective modulation of the light pulse. Simultaneously, the light intensity can reach the saturable absorption intensity of SESAM, thereby achieving a stable mode-locked state.

[0053] Furthermore, the pump source 1 is connected to the wavelength division multiplexer 3 via a pump protector 11. The pump source can convert electrical energy, optical energy, or other forms of energy into the laser beam required by the laser. The pump protector 11 is installed between the pump source and the wavelength division multiplexer 3 to filter out interference from ambient light or other non-pump light, and to prevent the laser beam from being reflected back to the pump source in the first or second resonant cavity, thus avoiding damage to the pump source and affecting its normal operation.

[0054] Furthermore, the first collimator 9 can also be used to collimate the pump light, making it better matched with the signal light, thereby improving pumping efficiency and the quality of the signal light.

[0055] Furthermore, the laser also includes a third polarization beamsplitter 13, with the second polarization beamsplitter 12, the first chirped fiber grating 14, and the third polarization beamsplitter 13 connected in sequence; and the second polarization beamsplitter 12, the narrow linewidth fiber grating 15, and the third polarization beamsplitter 13 connected in sequence. Specifically, the first chirped fiber grating 14 and the narrow linewidth fiber grating 15 are respectively disposed on one side of the second polarization beamsplitter 12, and the first chirped fiber grating 14 and the narrow linewidth fiber grating 15 form a parallel connection between the second polarization beamsplitter 12 and the third polarization beamsplitter 13; P-polarized light, after reaching the second polarization beamsplitter 12, enters the first chirped fiber grating 14 for negative dispersion compensation and is output from the third polarization beamsplitter 13, while S-polarized light, after reaching the second polarization beamsplitter 12, enters the narrow linewidth fiber grating 15 for filtering and is output from the third polarization beamsplitter 13.

[0056] This application utilizes the first chirped fiber grating 14 for wavelength filtering while providing negative dispersion to the resonant cavity, which can effectively reduce the mode-locking threshold and achieve mode-locking. Meanwhile, the narrow linewidth fiber grating 15 has a very narrow reflection bandwidth and can be used for wavelength locking and filtering in the second resonant cavity, ensuring that the wavelength of the laser output remains within a specific range and improving the stability and reliability of the picosecond laser.

[0057] Furthermore, the first resonant cavity also includes a circulator 16 and a second chirped fiber grating 17. The circulator 16 is disposed between the first chirped fiber grating 14 and the third polarization beam splitter 13, and the second chirped fiber grating 17 is connected to the circulator 16. The circulator 16 is a non-reciprocal optical path device, allowing the laser to propagate in a fixed direction and avoiding backlight interference. The femtosecond laser first passes through the first chirped fiber grating 14, and then the circulator 16 directs the light to the second chirped fiber grating 17. Since the femtosecond laser pulse is very short and its spectral width is wide, it is easily broadened by positive dispersion. Therefore, this application further increases negative dispersion through the second chirped fiber grating 17 for dispersion compensation, achieving narrow femtosecond pulse width output.

[0058] Furthermore, the laser also includes a second collimator 18, which is connected to the third polarization beam splitter 13. The femtosecond laser and the picosecond laser are output from the optical path end of the second collimator 18. The second collimator 18 can suppress beam diffusion of the femtosecond laser and the picosecond laser, reduce transmission loss, maintain high power density, thereby improving beam quality and optimizing energy transmission efficiency.

[0059] When the laser outputs femtosecond laser light, the laser beam generated by the pump source 1 passes sequentially through the pump protector 11, wavelength division multiplexer 3, and polarization-maintaining ytterbium-doped fiber 8 to the half-wave plate assembly 2. The motor adjusts the rotation angle of the half-wave plate to convert the polarization state of the laser to P-polarization. The P-polarized laser light is then polarized and split by the first polarization beam splitter 6, and focused onto the first reflector 4 by the first focusing lens 7 between the first reflector 4 and the first polarization beam splitter 6. The first reflector 4 then reflects the laser light, which passes sequentially through the first focusing lens 7, the first polarization beam splitter 6, the half-wave plate assembly 2, the first collimator 9, the polarization-maintaining ytterbium-doped fiber 8, and the wavelength division multiplexer 3 before reaching the second polarization beam splitter 12. At this point, the linear polarization direction remains unchanged. The light passes through the second polarization beamsplitter 12 and reaches the first chirped fiber grating 14. The first chirped fiber grating 14 provides a certain negative dispersion. At this time, the first reflector 4, the first focusing lens 7, the first polarization beamsplitter 6, the half-wave plate assembly 2, the first collimator 9, the polarization-maintaining ytterbium-doped fiber 8, the wavelength division multiplexer 3, the pump protector 11, the pump source, the second polarization beamsplitter 12, and the first chirped fiber grating 14 constitute a first resonant cavity, realizing mode-locking of the femtosecond laser. Since the pulse width is less than 5 ps at this time, the laser passes through the circulator 16 and reaches the second chirped fiber grating 17. After the second chirped fiber grating 17 provides negative dispersion again, it is reflected to the circulator 16, and after passing through the third polarization beamsplitter 13 and the second collimator 18, the femtosecond laser is output from the optical path end of the second collimator 18.

[0060] When the laser outputs picosecond laser light, the laser beam generated by the pump source 1 passes sequentially through the pump protector 11, wavelength division multiplexer 3, and polarization-maintaining ytterbium-doped fiber 8 to the half-wave plate assembly 2. The motor adjusts the rotation angle of the half-wave plate to convert the polarization state of the laser to S-polarization. The S-polarized laser light is then polarized and split by the first polarization beam splitter 6, and focused onto the second reflector 5 by the first focusing lens 7 between the second reflector 5 and the first polarization beam splitter 6. The second reflector 5 then reflects the laser light, which then passes sequentially through the first focusing lens 7, the first polarization beam splitter 6, the half-wave plate assembly 2, and the first collimator 9. After passing through the polarization-maintaining ytterbium-doped fiber 8 and the wavelength division multiplexer 3, the laser reaches the second polarization beamsplitter 12. Since the laser is P-polarized, it enters the narrow linewidth fiber grating 15. At this time, the second reflector 5, the first focusing lens 7, the first polarization beamsplitter 6, the half-wave plate assembly 2, the first collimator 9, the polarization-maintaining ytterbium-doped fiber 8, the wavelength division multiplexer 3, the pump protector 11, the pump source, the second polarization beamsplitter 12, and the narrow linewidth fiber grating 15 constitute a second resonant cavity, realizing picosecond laser mode-locking. The laser output from the narrow linewidth fiber grating 15 passes through the third polarization beamsplitter 13 and reaches the second collimator 18, and is output from the optical path end of the second collimator 18. This application combines picosecond and femtosecond resonant cavities, allowing the output laser pulse width to be switched by adjusting the motor. This eliminates the need for two lasers, enabling the laser to output both femtosecond and picosecond lasers, thus reducing operating costs. Furthermore, the optical path design is simple and highly compatible; adjusting the half-wave plate assembly 2 allows the laser to switch between different outputs. The stable output of both femtosecond and picosecond lasers ensures stable laser operation and improves the laser's performance.

[0061] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A laser, characterized by, include: Pump source (1) is used to generate a laser beam; Wavelength division multiplexer (3) is connected to the output of the pump source (1); A polarization-maintaining ytterbium-doped fiber (8) is connected to the wavelength division multiplexer (3) for generating laser light; The first collimator (9) is connected to the polarization-maintaining ytterbium-doped fiber (8) and is used to collimate the laser. A half-wave plate assembly (2) is connected to the first collimator (9) and is used to change the polarization direction of the laser. The first polarization beam splitter (6) is connected to the half-wave plate assembly (2) and is used to receive the laser after the polarization direction is changed and separate it into P-polarized light or S-polarized light. The first reflector (4) and the second reflector (5) are respectively disposed on one side of the first polarization beam splitter (6) for reflecting P-polarized light or S-polarized light to the half-wave plate assembly (2). The second polarization beam splitter (12) is connected to the wavelength division multiplexer (3) and is used to receive the laser light reflected by the first reflector (4) or the second reflector (5) to the half-wave plate assembly (2) and then passing through the first collimator (9), the polarization-maintaining ytterbium-doped fiber (8) and the wavelength division multiplexer (3) in sequence. A first chirped fiber grating (14) is disposed on one side of the second polarization beam splitter (12) for receiving P-polarized light separated by the second polarization beam splitter (12) and providing negative dispersion for the P-polarized light. A narrow linewidth fiber grating (15) is disposed on the other side of the second polarization beam splitter (12) to receive the S-polarized light separated by the second polarization beam splitter (12) and to filter the S-polarized light. Wherein, the S-polarized light is either a femtosecond laser or a picosecond laser, and the P-polarized light is either a femtosecond laser or a picosecond laser. The pump source (1), half-wave plate assembly (2), wavelength division multiplexer (3), first reflector (4), first polarization beam splitter (6), polarization-maintaining ytterbium-doped fiber (8), first collimator (9), second polarization beam splitter (12), and first chirped fiber grating (14) constitute a first resonant cavity for outputting femtosecond laser. The pump source (1), half-wave plate assembly (2), wavelength division multiplexer (3), second reflector (5), first polarization beam splitter (6), polarization-maintaining ytterbium-doped fiber (8), first collimator (9), second polarization beam splitter (12), and narrow linewidth fiber grating (15) constitute a second resonant cavity for outputting picosecond laser.

2. The laser of claim 1, wherein, The half-wave plate assembly (2) includes a motor and a half-wave plate, the half-wave plate being disposed on the output end of the motor, and the motor being used to adjust the rotation angle of the half-wave plate.

3. The laser according to claim 1, characterized in that, The first reflector (4) is selected from a femtosecond semiconductor saturable absorber mirror.

4. The laser according to claim 1, characterized in that, The second reflector (5) is selected from a picosecond semiconductor saturable absorber mirror.

5. The laser according to claim 1, characterized in that, A first focusing lens (7) is also provided between the first polarizing beam splitter (6) and the first reflector (4).

6. The laser according to claim 1, characterized in that, A first focusing lens (7) is also provided between the first polarizing beam splitter (6) and the second reflector (5).

7. The laser according to claim 1, characterized in that, The pump source (1) is connected to the wavelength division multiplexer (3) through a pump protector (11).

8. The laser according to any one of claims 1 to 7, characterized in that, The laser also includes a third polarization beam splitter (13), and the second polarization beam splitter (12), the first chirped fiber grating (14) and the third polarization beam splitter (13) are connected in sequence; and the second polarization beam splitter (12), the narrow linewidth fiber grating (15) and the third polarization beam splitter (13) are connected in sequence.

9. The laser according to claim 8, characterized in that, The first resonant cavity further includes a circulator (16) and a second chirped fiber grating (17). The circulator (16) is disposed between the first chirped fiber grating (14) and the third polarization beam splitter (13). The second chirped fiber grating (17) is connected to the circulator (16).

10. The laser according to claim 8, characterized in that, The laser also includes a second collimator (18), which is connected to the third polarization beam splitter (13). The femtosecond laser and the picosecond laser are output from the optical path end of the second collimator (18).

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