Astigmatism compensation optical gain cavity laser system

Abstract

The invention is suitable for the technical field of optical systems, and provides an astigmatism compensation optical gain cavity laser system which comprises an incident laser system, an optical cavity system and a feedback system. According to the astigmatism compensation optical gain cavity laser system, the incident laser system, the optical cavity system and the feedback system are arranged, and the astigmatism compensation optical gain cavity device remarkably improves the optical cavity coupling rate through optical matching and photoelectric modulation of the incident laser system; a 90-degree included angle cylindrical mirror group arranged in the optical cavity system is utilized to accurately eliminate astigmatism and realize regulation and control of the size of a light spot, so that the laser keeps circular Gaussian fundamental mode operation; by combining the PDH technology and PID control of a feedback system, stable locking of the laser and the optical cavity is realized, the device can effectively solve the problem of light spot ellipse caused by astigmatism in the optical cavity, the laser conversion efficiency and stability and the light beam quality are remarkably improved, and finally a laser system with high efficiency and good stability and light beam quality is obtained.

Description

Technical Field

[0001] This invention belongs to the field of optical system technology, and particularly relates to an astigmatic compensation optical gain cavity laser system. Background Technology

[0002] In fields such as intracavity nonlinear frequency conversion (e.g., intracavity frequency doubling, sum-frequency, difference-frequency conversion), cavity-enhanced spectroscopy (e.g., cavity ring-down spectroscopy, cavity-enhanced absorption spectroscopy, intracavity laser absorption spectroscopy), and photocathode-driven laser systems of steady-state micro-beam (SSMB) extreme ultraviolet light sources, to obtain high conversion efficiency, high measurement sensitivity, or high-quality electron beams, the laser typically needs to operate in a circular fundamental mode within the optical gain cavity. Circular fundamental mode lasers have a symmetrical Gaussian energy distribution, beam waists in two orthogonal directions are the same as Rayleigh lengths, divergence and depth of focus are isotropic, peak intensity distribution is controllable during focusing, nonlinear interaction and phase matching are uniform, and they possess minimum beam divergence angle, stable transmission characteristics, and high nonlinear conversion efficiency, which are key to ensuring the performance of the aforementioned applications.

[0003] This invention was developed and improved upon by the National Key Research and Development Program of China, specifically the 50MeV electron injector research project for steady-state micro-beam (SSMB) extreme ultraviolet light source (Project 3: Development of GHz repetition rate driven laser, Project No.: 2024YFB2807503), addressing the shortcomings of existing technologies.

[0004] In practical applications, the laser spot inside the optical cavity is often elliptical. This is mainly due to astigmatism generated by the cavity components. Astigmatism occurs when a conical beam emitted from an off-axis object point passes through an optical system, and the optical path lengths in the meridional and sagittal directions are unequal. Consequently, the meridional and sagittal focal lines do not coincide on the image plane, resulting in the inability to form a clear image point and instead producing a diffuse spot. A significant factor contributing to astigmatism is the laser's incidence at a non-zero angle onto the spherical mirror: for a concave mirror with a radius of curvature R, when the incident light is at an angle θ, the effective radius of curvature R in the x-direction (incident plane) is... x =Rcosθ, the effective radius of curvature R in the y-direction (perpendicular to the incident plane) y =R / cosθ, as long as θ is not zero, the effective radii of curvature in the x and y directions will not be equal, which will lead to astigmatism. Elliptical spot will cause the laser to diverge and focus in different axes, thermally induced aberrations to be non-uniform and alignment tolerance to be strict, which will seriously reduce the laser conversion efficiency, stability and beam quality, and cannot meet the requirements of intracavity nonlinear frequency conversion, cavity enhancement spectroscopy technology and SSMB extreme ultraviolet light source photocathode driven laser system for circular Gaussian mode laser.

[0005] Currently, there are still shortcomings in the compensation schemes for astigmatism within optical cavities. It is difficult to simultaneously achieve efficient elimination of astigmatism, flexible control of spot size, and stable locking of the laser and the optical cavity. Therefore, there is an urgent need for an optical gain cavity device that can solve the above problems. Summary of the Invention

[0006] This invention provides an optical gain cavity laser system with astigmatism compensation, aiming to solve the problem in the prior art where astigmatism within the optical cavity causes the laser spot to be elliptical, affecting laser conversion efficiency, stability and beam quality.

[0007] The present invention is implemented as follows: an astigmatism-compensated optical gain cavity laser system, comprising an incident laser system, an optical cavity system, and a feedback system; The incident laser system is connected to the optical cavity system and is used to inject optically matched and photoelectrically modulated laser light into the optical cavity system; The optical cavity system is used to achieve laser resonance enhancement and astigmatism compensation, and the optical cavity system has a built-in cylindrical mirror group; The feedback system is connected to both the incident laser system and the optical cavity system, and is used to monitor the laser signal and generate a control signal to stabilize the laser on the optical cavity system.

[0008] Preferably, the incident laser system includes a laser injection system, an optical matching module, and a photoelectric modulation module; The laser injection system consists of a laser seed source and a laser amplifier. The laser seed source provides the initial input laser, and the laser amplifier amplifies the power of the initial input laser. The optical matching module consists of a lens group composed of several lenses and a polarization matching group composed of several polarizers. It is used to perform optical transverse mode matching and polarization matching on the amplified laser. The photoelectric modulation module consists of an electro-optic modulator and an acousto-optic modulator. It is used to perform phase modulation and frequency modulation on the optically matched laser.

[0009] Preferably, the optical cavity system is a passive optical resonant cavity, comprising a plurality of ultra-high reflectivity cavity mirrors and the cylindrical mirror group; The ultra-high reflectivity cavity mirror includes a plane mirror and a concave mirror. The configuration of the optical cavity system is selected from any one of a two-mirror optical cavity, a three-mirror optical cavity, a four-mirror bowtie-type optical cavity, or a four-mirror fully curved surface optical cavity. The cylindrical mirror group consists of two cylindrical mirrors placed at a 90° angle, and the generatrices of the two cylindrical mirrors are perpendicular to each other.

[0010] Preferably, for a radius of curvature of The concave mirror has effective radii of curvature in the x-direction of the incident plane and in the y-direction perpendicular to the incident plane, respectively. x = cos , y = / cos ; For the cylindrical mirror, the effective radii of curvature in the x-direction and the y-direction are respectively... x = , y =∞, the corresponding ABCD matrices are [ .

[0011] Preferably, the feedback system includes an error signal generation module and a PID module; The error signal generation module is used to monitor the reflected light signal of the optical cavity system, extract the phase difference information between the laser and the optical cavity, and generate an error signal. The PID module is used to convert the error signal into a control signal and transmit the control signal to the laser seed source of the incident laser system to adjust the cavity length of the laser seed source.

[0012] Preferably, the error signal generation module uses Pound-Drever-Hall technology to generate the error signal. The implementation process of Pound-Drever-Hall technology includes: using a phase modulator to perform phase modulation on the incident laser at an angular frequency Ω and a modulation depth β, so that the laser generates a sideband with a frequency of ω±nΩ; monitoring the reflected laser from the input coupling mirror of the optical cavity system through a photodiode; demodulating the reflected laser signal using a mixer, wherein the mixer and the phase modulator are driven synchronously by the same radio frequency signal source, and the phase difference between the modulated and demodulated signals is π / 2; and performing low-pass filtering on the demodulated signal to obtain the Pound-Drever-Hall error signal.

[0013] Preferably, the laser seed source of the incident laser system has a built-in piezoelectric ceramic, and the control signal output by the PID module acts on the piezoelectric ceramic to achieve continuous tuning of the laser seed source cavity length by adjusting the piezoelectric ceramic.

[0014] Preferably, the optical matching module designs the external matching optical path according to the ABCD law, adjusts the lateral dimension and propagation angle of the injected laser, so that the injected laser and the intrinsic mode of the optical cavity system perfectly overlap in the lateral space, and the incident optical axis coincides with the optical cavity optical axis.

[0015] Preferably, the laser injected by the incident laser system is a continuous laser or a pulsed laser.

[0016] Preferably, by replacing cylindrical mirrors with different curvatures, the focal length of the cylindrical mirror group can be adjusted, thereby controlling the size of the laser spot within the optical cavity system.

[0017] Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: The astigmatism-compensated optical gain cavity laser system of the present invention significantly improves the optical cavity coupling rate through optical matching and photoelectric modulation of the incident laser system; by utilizing the 90° included-angle cylindrical mirror group built into the optical cavity system, astigmatism is precisely eliminated and the spot size is controlled, so that the laser maintains circular Gaussian mode operation; combined with the PDH technology and PID control of the feedback system, stable locking between the laser and the optical cavity is achieved. This device can effectively solve the problem of spot ellipticity caused by astigmatism in the optical cavity, significantly improve the laser conversion efficiency, stability and beam quality, and finally obtain a laser system with high efficiency, good stability and beam quality. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the optical path design of the present invention; Figure 2 This is a schematic diagram of the optical cavity system in this invention; Figure 3 This is an optical path analysis diagram of the present invention without inserting a cylindrical mirror; Figure 4 This is an optical path analysis diagram after inserting the cylindrical mirror in this invention; Figure 5 These are various optical cavity configuration diagrams of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] Please see Figure 1-5 The present invention provides a technical solution: an astigmatism-compensated optical gain cavity laser system, comprising an incident laser system, an optical cavity system and a feedback system; The incident laser system is connected to the optical cavity system and is used to inject optically matched and photoelectrically modulated laser light into the optical cavity system; The optical cavity system is used to achieve laser resonance enhancement and astigmatism compensation, and the optical cavity system has a built-in cylindrical mirror group; The feedback system is connected to both the incident laser system and the optical cavity system, and is used to monitor the laser signal and generate a control signal to stabilize the laser on the optical cavity system.

[0021] The incident laser system includes a laser injection system, an optical matching module, and an optoelectronic modulation module; The laser injection system consists of a laser seed source and a laser amplifier. The laser seed source provides the initial input laser, and the laser amplifier amplifies the power of the initial input laser. The optical matching module consists of a lens group composed of several lenses and a polarization matching group composed of several polarizers. It is used to perform optical transverse mode matching and polarization matching on the amplified laser. The photoelectric modulation module consists of an electro-optic modulator and an acousto-optic modulator. It is used to perform phase modulation and frequency modulation on the optically matched laser.

[0022] The optical cavity system is a passive optical resonant cavity, comprising several ultra-high reflectivity cavity mirrors and the cylindrical mirror group; The ultra-high reflectivity cavity mirror includes a plane mirror and a concave mirror. The configuration of the optical cavity system is selected from any one of a two-mirror optical cavity, a three-mirror optical cavity, a four-mirror bowtie-type optical cavity, or a four-mirror fully curved surface optical cavity. The cylindrical mirror group consists of two cylindrical mirrors placed at a 90° angle, and the generatrices of the two cylindrical mirrors are perpendicular to each other.

[0023] The feedback system includes an error signal generation module and a PID module; The error signal generation module is used to monitor the reflected light signal of the optical cavity system, extract the phase difference information between the laser and the optical cavity, and generate an error signal. The PID module is used to convert the error signal into a control signal and transmit the control signal to the laser seed source of the incident laser system to adjust the cavity length of the laser seed source.

[0024] For the radius of curvature is The concave mirror has effective radii of curvature in the x-direction of the incident plane and perpendicular to the y-direction of the incident plane, respectively. x = cos , y = / cos ; For the cylindrical mirror, the effective radii of curvature in the x-direction and the y-direction are respectively... x = , y =∞, the corresponding ABCD matrices are [ .

[0025] The error signal generation module uses Pound-Drever-Hall (PDH) technology to generate the error signal. The implementation process of the PDH technology includes: using a phase modulator to modulate the incident laser with an angular frequency Ω and a modulation depth β, so that the laser generates a sideband with a frequency of ω±nΩ (n is an integer); monitoring the reflected laser from the input coupling mirror of the optical cavity system through a photodiode; demodulating the reflected laser signal using a mixer, wherein the mixer and the phase modulator are driven synchronously by the same radio frequency signal source, and the phase difference between the modulated and demodulated signals is π / 2; and performing low-pass filtering on the demodulated signal to obtain the PDH error signal.

[0026] The laser seed source of the incident laser system has a built-in piezoelectric ceramic (PZT). The control signal output by the PID module acts on the piezoelectric ceramic, and the continuous tuning of the laser seed source cavity length is achieved by adjusting the piezoelectric ceramic.

[0027] The optical matching module designs the external matching optical path according to the ABCD law, adjusts the lateral dimension and propagation angle of the injected laser, so that the injected laser and the intrinsic mode of the optical cavity system perfectly overlap in the lateral space, and the incident optical axis coincides with the optical cavity optical axis.

[0028] The laser injected by the incident laser system is either a continuous laser or a pulsed laser.

[0029] By replacing cylindrical mirrors with different curvatures, the focal length of the cylindrical mirror group can be adjusted, thereby controlling the size of the laser spot within the optical cavity system.

[0030] The incident laser system uses a narrow-linewidth laser seed source with an output wavelength of 1064nm (integration time jitter <300fs in [10Hz, 1MHz]), paired with a high-power Nd:YAG laser amplifier to amplify the laser power to 10W. The optical matching module consists of two concave and convex lenses (focal lengths of -50mm and 100mm respectively) and two polarizers (half-wave and quarter-wave). The optical path is designed using the ABCD law to match the transverse dimensions and propagation angle of the injected laser with the eigenmode of the optical cavity, and the polarization direction is consistent with the polarization requirements of the optical cavity. The optoelectronic modulation module uses lithium niobate (LiNbO). 3）电光调制器（调制频率 A 10MHz modulator and an acousto-optic modulator (modulation frequency 110MHz) are used to achieve phase modulation and frequency modulation of the laser, respectively.

[0031] The optical cavity system adopts a four-mirror bowtie configuration, including two plane mirrors (M1, reflectivity > 99.9%, M2, reflectivity > 99.99%) and two concave mirrors (M3, M4, radius of curvature R = 1m, reflectivity > 99.99%). The cylindrical mirror group consists of two cylindrical mirrors (C1, C2), with C1 having a radius of curvature R1 = 0.8m and C2 having a radius of curvature R2 = 1.2m. The two are placed at a 90° angle, with their generatrices perpendicular to each other, and are placed in the optical path between M1 and M2.

[0032] The error signal generation module in the feedback system includes a photodiode (response speed > 100MHz), a 10MHz RF signal source, a mixer, and a low-pass filter (cutoff frequency 1MHz); the PID module uses a high-precision digital PID controller (bandwidth > 10kHz); the laser seed source has a built-in piezoelectric ceramic (PZT, displacement accuracy < 1nm) and is connected to the output of the PID module.

[0033] When the system is working, the initial 1064nm laser from the laser seed source is amplified to 10W by the laser amplifier and then enters the optical matching module: the lens group adjusts the lateral size and propagation angle of the laser so that the beam waist radius of the laser at the input coupling mirror M1 of the optical cavity is consistent with the beam waist radius of the intrinsic mode of the optical cavity, and the divergence angle is adjusted; the polarizer adjusts the polarization direction of the laser to match the polarization requirements of the optical cavity, improving the coupling efficiency of the optical cavity to >80%; subsequently, the electro-optic modulator of the opto-modulation module performs phase modulation of the laser at an angular frequency of 10MHz and a modulation depth of β=0.1rad, and the acousto-optic modulator performs frequency modulation of the laser at a frequency of 110MHz, generating a modulated laser with sidebands; the modulated laser is injected into the optical cavity system through M1 and propagates back and forth between M1, M2, M3, and M4 to achieve resonance enhancement: since M3 and M4 have a non-0-degree incident angle θ (θ=10°), the effective radius of curvature R in the x-direction is 10° when the cylindrical mirror is not inserted. x =Rcosθ≈0.9848m, effective radius of curvature R in the y-direction y=R / cosθ≈1.004m (precise value is 1.0154m), resulting in an elliptical beam spot. After inserting C1 and C2, C1 focuses the beam in the x-direction (aligned with the main astigmatism direction), and C2 diverges the beam in the y-direction. By precisely controlling the positions of C1 and C2, the wavefront curvature of the beam in both the x and y directions is made consistent with the resonance requirements of the optical cavity, ultimately forming a circular beam spot (ellipticity <1.05). At the same time, the optical cavity resonates and amplifies the laser, increasing the intracavity circulating power to >10kW. The photodiode monitors the reflected light signal of M1 and extracts the phase difference information between the laser and the optical cavity. The radio frequency signal source synchronously drives the electro-optic modulator and mixer. The mixer demodulates the reflected light signal (the phase difference between the modulated and demodulated signals is π / 2). After filtering by the low-pass filter, the PDH error signal is obtained. The PID module converts the error signal into a control signal, drives the PZT of the laser seed source, adjusts the seed source cavity length, and keeps the laser frequency consistent with the optical cavity resonant frequency to achieve stable locking. After locking, the laser frequency drift is <1kHz / h.

[0034] Astigmatism arises from the varying focusing capabilities of an optical system on different meridional and sagittal planes. Within an optical cavity, this asymmetry causes the laser spot to appear elliptical rather than a perfect circle. Cylindrical mirror arrays eliminate astigmatism primarily based on the unidirectional focusing characteristics of cylindrical mirrors and astigmatism compensation mechanisms. Cylindrical mirrors possess unidirectional focusing capability, having optical power only in the direction perpendicular to their generatrix, and no focusing effect in the parallel direction. This characteristic allows them to independently adjust the divergence angle of the beam in different directions. A system consisting of two cylindrical mirrors is used. The first cylindrical mirror is placed on the main beam path, with its generatrix aligned with the main direction of astigmatism. The second cylindrical mirror is rotated 90° and positioned so that its generatrix is ​​aligned with the main direction of astigmatism. The line direction is perpendicular to the first cylindrical mirror. If the first cylindrical mirror focuses or diverges the beam in a certain direction (such as the x-direction), then the second cylindrical mirror is adjusted in the opposite direction (y-direction). By precisely adjusting the focal length and position of the two cylindrical mirrors, the same beam parameters can be achieved in two mutually perpendicular directions. Ultimately, the wavefront curvature and beam size of the beam in the x and y directions are made consistent. This method can precisely control the propagation characteristics of the beam in different directions, effectively eliminate astigmatism, and restore the elliptical beam spot to a high-quality circular beam spot. In addition, by replacing cylindrical mirrors with different curvatures, we can precisely adjust the size of the beam spot according to different needs.

[0035] The optical path analysis diagram of this invention in a bowtie-shaped four-mirror optical cavity without inserting a cylindrical mirror is shown in the attached specification. Figure 3 As shown, assume that the ABCD matrices of laparoscopes M1, M2, M3, and M4 are respectively M 1 、M 3 、M5 、M 7 The ABCD matrices of the four arms L1, L2, L3, and L4 are respectively M 2 、M 4 、M 6 、M 8 ,in M 1 、M 3 All are [ , M 2 、M 4 、M 6 、M 8 They are respectively [ 、[ 、[ 、[ For concave mirrors M3 and M4, their ABCD matrix and incident angle... Related, in the x direction is [ In the y-direction, it is [ For a radius of curvature of The effective radii of curvature of the curved mirror in the x-direction (incident plane) and y-direction (perpendicular to the incident plane) are respectively... x = cos , y = / cos Given a focal length f = R / 2, the round-trip ABCD matrices in the x and y directions at point M1 are as follows: M x = M8 M7 M6 M5 M4 M3 M2 M1=[ M y = M8 M7 M6 M5 M4 M3 M2 M1=[ For a Gaussian laser beam (taking the x-direction as an example), its beam waist radius is: in, The Rayleigh distance (the beam waist area divided by the wavelength in the x-direction), i.e., the distance where the beam waist area is equal to twice the beam waist area, is the radius of curvature R of the equiphase surface of the Gaussian beam. x (z) is: A Gaussian beam is formed by a radius of curvature R x (z), Waist width w x The beam can be determined by any two of z (z) and the beam position z. Therefore, the three quantities mentioned above can be related by the complex parameter q, which can more simply describe the transmission and transformation of the Gaussian beam. The complex parameter q of the Gaussian beam is defined as follows: In the formula, M2 is the beam quality factor of the Gaussian beam, and its value is 1 since the fundamental mode is a Gaussian beam.

[0036] The transformation of the complex parameter q of the Gaussian beam through the transformation matrix M of the optical system obeys the ABCD law, as follows: In a laser cavity, the condition for steady-state oscillation is that after a Gaussian beam completes one round trip within the cavity, its complex beam parameter q can be reproduced. Therefore, the beam waist radius at any position in the cavity can be calculated using the ABCD matrix. Similarly, for the y-direction, the beam waist radius at any position in the optical cavity can be expressed as: The formula above gives the spot radius on the reference plane selected when calculating the round-trip matrix. If you want to know the spot size at other locations in the cavity, you need to use that location as the new reference plane and recalculate the round-trip matrix.

[0037] The optical path analysis diagram of this invention after inserting a cylindrical mirror in a bowtie-shaped four-mirror optical cavity is shown in the attached specification. Figure 4 As shown, assume that the ABCD matrices of the endoscopes M1, C1, C2, M2, M3, and M4 are respectively M 1 、M 3 、M 5 、M 7、M 9 、M 11 The ABCD matrices of the six arms L1, L2, L3, L4, L5, and L6 are respectively M 2 、M 4 、M 6 、M 8 、M 10 、M 12 ， in M 1 、M 3 All are [ , M 2 、M 4 、M 6 、M 8 、M 10 、M 12 They are respectively [ 、[ 、[ 、[ 、[ 、[ For concave mirrors M3 and M4, their ABCD matrix and incident angle... Related, in the x direction is [ In the y-direction, it is [ For a radius of curvature of The effective radii of curvature of the curved mirror in the x-direction (incident plane) and y-direction (perpendicular to the incident plane) are respectively... x = cos , y = / cos Given a focal length f = R / 2, for a cylindrical mirror, the effective radii of curvature in the x-direction (curvature direction) and y-direction (plane direction) are respectively... x = , y =∞, the corresponding ABCD matrices are [ Unlike spherical mirrors, cylindrical mirrors produce astigmatism in only one direction while maintaining ideal planar reflection characteristics in the other. Therefore, their characteristics can be used to shape the light spot in one direction. Thus, the round-trip ABCD matrices in the x and y directions at M1 are as follows: M x = M12 M11 M10 M9 M8 M7 M6 M5 M4 M3 M2 M1=[ M y = M12 M11 M10 M9 M8 M7 M6 M5 M4 M3 M2 M1=[ By providing specific ABCD matrix parameters for a particular optical cavity system, the laser spot radius in the x and y directions at any location can be calculated. By appropriately adjusting the cylindrical mirror group, the spot in a specific direction can be shaped, ultimately achieving circular spot operation. Furthermore, by replacing cylindrical mirrors with different curvatures, the spot size can be controlled, providing better options for applications with different needs.

[0038] The optical cavity configurations in the system of this invention, in addition to the four-mirror bowtie type optical cavity configuration, also include, but are not limited to, two-mirror, three-mirror, and four-mirror fully curved surface optical cavity configurations, as shown in the appendix to the specification. Figure 5 As shown.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An astigmatism-compensated optical gain cavity laser system, characterized in that: This includes the incident laser system, the optical cavity system, and the feedback system; The incident laser system is connected to the optical cavity system and is used to inject optically matched and photoelectrically modulated laser light into the optical cavity system; The optical cavity system is used to achieve laser resonance enhancement and astigmatism compensation, and the optical cavity system has a built-in cylindrical mirror group; The feedback system is connected to both the incident laser system and the optical cavity system, and is used to monitor the laser signal and generate a control signal to stabilize the laser on the optical cavity system.

2. The astigmatism-compensated optical gain cavity laser system as described in claim 1, characterized in that: The incident laser system includes a laser injection system, an optical matching module, and an optoelectronic modulation module; The laser injection system consists of a laser seed source and a laser amplifier. The laser seed source provides the initial input laser, and the laser amplifier amplifies the power of the initial input laser. The optical matching module consists of a lens group composed of several lenses and a polarization matching group composed of several polarizers. It is used to perform optical transverse mode matching and polarization matching on the amplified laser. The photoelectric modulation module consists of an electro-optic modulator and an acousto-optic modulator. It is used to perform phase modulation and frequency modulation on the optically matched laser.

3. The astigmatism-compensated optical gain cavity laser system as described in claim 1, characterized in that: The optical cavity system is a passive optical resonant cavity, comprising several ultra-high reflectivity cavity mirrors and the cylindrical mirror group; The ultra-high reflectivity cavity mirror includes a plane mirror and a concave mirror. The configuration of the optical cavity system is selected from any one of a two-mirror optical cavity, a three-mirror optical cavity, a four-mirror bowtie-type optical cavity, or a four-mirror fully curved surface optical cavity. The cylindrical mirror group consists of two cylindrical mirrors placed at a 90° angle, and the generatrices of the two cylindrical mirrors are perpendicular to each other.

4. The astigmatism-compensated optical gain cavity laser system as described in claim 3, characterized in that: For the radius of curvature is The concave mirror has effective radii of curvature in the x-direction of the incident plane and in the y-direction perpendicular to the incident plane, respectively. x = cos , y = / cos ; For the cylindrical mirror, the effective radii of curvature in the x-direction and the y-direction are respectively... x = , y =∞, the corresponding ABCD matrices are [ .

5. The astigmatism-compensated optical gain cavity laser system as described in claim 1, characterized in that: The feedback system includes an error signal generation module and a PID module; The error signal generation module is used to monitor the reflected light signal of the optical cavity system, extract the phase difference information between the laser and the optical cavity, and generate an error signal. The PID module is used to convert the error signal into a control signal and transmit the control signal to the laser seed source of the incident laser system to adjust the cavity length of the laser seed source.

6. The astigmatism-compensated optical gain cavity laser system as described in claim 5, characterized in that: The error signal generation module uses Pound-Drever-Hall technology to generate the error signal. The implementation process of Pound-Drever-Hall technology includes: using a phase modulator to modulate the incident laser with an angular frequency Ω and a modulation depth β, so that the laser generates a sideband with a frequency of ω±nΩ; monitoring the reflected laser from the input coupling mirror of the optical cavity system through a photodiode; demodulating the reflected laser signal using a mixer, wherein the mixer and the phase modulator are driven synchronously by the same radio frequency signal source, and the phase difference between the modulated and demodulated signals is π / 2; and performing low-pass filtering on the demodulated signal to obtain the Pound-Drever-Hall error signal.

7. The astigmatism-compensated optical gain cavity laser system as described in claim 5, characterized in that: The laser seed source of the incident laser system has a built-in piezoelectric ceramic, and the control signal output by the PID module acts on the piezoelectric ceramic to achieve continuous tuning of the laser seed source cavity length by adjusting the piezoelectric ceramic.

8. The astigmatism-compensated optical gain cavity laser system as described in claim 2, characterized in that: The optical matching module designs the external matching optical path according to the ABCD law, adjusts the lateral dimension and propagation angle of the injected laser, so that the injected laser and the intrinsic mode of the optical cavity system perfectly overlap in the lateral space, and the incident optical axis coincides with the optical cavity optical axis.

9. The astigmatism-compensated optical gain cavity laser system as described in claim 1, characterized in that: The laser injected by the incident laser system is either a continuous laser or a pulsed laser.

10. The astigmatism-compensated optical gain cavity laser system as described in claim 3, characterized in that: By replacing cylindrical mirrors with different curvatures, the focal length of the cylindrical mirror group can be adjusted, thereby controlling the size of the laser spot within the optical cavity system.

Images