Laser amplification system, laser amplifier, and laser processing apparatus

Abstract

The application relates to the technical field of laser amplification. A laser amplification system comprises a gain module and a mirror reflection module. The gain module has a first reflection surface and a gain medium which are stacked. The first reflection surface is used for reflecting laser light. The first reflection surface is recessed from the gain medium towards the first reflection surface. Laser light is incident into the first reflection surface from the gain medium towards the first reflection surface. The mirror reflection module is located on the reflection side of the gain module and comprises a plane mirror and a folded mirror. The folded mirror is located between the gain module and the plane mirror. The folded mirror comprises a second reflection surface and a third reflection surface which are perpendicular to each other and face the plane mirror. The second reflection surface and the third reflection surface are used for making the laser light incident into the folded mirror and the laser light emitted from the folded mirror parallel. The laser amplification system satisfies the above structure, realizes folding of the optical path of laser light, and can compensate for thermal lens effect in the laser amplification system.

Description

Technical Field

[0001] This application relates to the field of laser amplification technology, and in particular to a laser amplification system, a laser amplifier, and a laser processing device. Background Technology

[0002] With the development of solid-state lasers, the requirements for output laser power and beam quality are becoming increasingly stringent to suit various laser applications. Solid-state thin-film lasers typically use sheet-like crystals with thicknesses on the order of hundreds of micrometers as the gain medium. This sheet-like gain medium has advantages such as good heat dissipation, low thermal effects, and weak nonlinear effects. When the laser passes through the sheet-like gain medium, which is in a population inversion state, not only is the laser power amplified, but high beam quality is also ensured. Due to the thinness of the sheet-like gain medium, the amplification effect of the laser passing through it once is relatively low. Therefore, the amplified laser needs to pass through the sheet-like gain medium multiple times to achieve high average power and high beam quality laser output.

[0003] A thin-plate multi-pass laser amplifier is an amplifier that allows a seed laser to pass through a sheet-like gain medium multiple times. A multi-pass laser amplifier typically includes a gain module and a plane mirror assembly. The gain module has a sheet-like gain medium, and the plane mirror assembly is used to reflect the laser multiple times to the sheet-like gain medium to achieve multiple amplification of the laser. Due to the size and stability limitations of the thin-plate multi-pass laser amplifier, the optical path length of the laser within the amplifier is limited. To ensure that the laser beam waist is located at the plane mirror and to guarantee the self-reproduction of the spot size at the sheet-like gain medium, the sheet-like gain medium is required to have a large radius of curvature, resulting in a small surface curvature, which increases the difficulty of fabricating the sheet-like gain medium. Furthermore, the multiple reflections of the laser to the sheet-like gain medium cause multiple overlapping spots, easily leading to thermal lensing effects and affecting the self-reproduction of the laser. Summary of the Invention

[0004] This application provides a laser amplification system, a laser amplifier, and a laser processing device. By setting a folded reflector to fold the optical path, the total length of the laser amplification system can be shortened, the power and pointing stability of the laser amplification system can be improved, and the thermal lensing effect at the gain medium can be compensated to ensure the self-reproduction of the laser in the entire laser amplification system.

[0005] In a first aspect, this application provides a laser amplification system, comprising: a gain module having a stacked first reflective surface and a gain medium, the first reflective surface being used to reflect laser light, the first reflective surface being recessed from the gain medium toward the first reflective surface, and the surface of the gain medium facing away from the first reflective surface being the laser incident surface of the gain module; and a mirror reflection module located on the reflecting side of the gain module, comprising a plane mirror and a folded mirror, the folded mirror being located between the gain module and the plane mirror, the folded mirror comprising a second reflective surface and a third reflective surface facing the plane mirror, the second reflective surface and the third reflective surface being perpendicular to each other, for making the laser light incident into the folded mirror and the laser light emitted from the folded mirror parallel.

[0006] The laser amplification system of this application embodiment has a mirror reflection module on the side of the gain module. The mirror reflection module includes a plane mirror and a planar mirror. The reflecting surface of the plane mirror faces the gain module, allowing the laser entering the laser amplification system to be reflected multiple times between the gain module and the plane mirror, achieving multiple amplification of the laser. By placing the planar mirror between the gain module and the plane mirror, with the second and third reflecting surfaces of the planar mirror facing the plane mirror, the laser can be reflected multiple times between the planar mirror and the planar mirror, achieving folding of the optical path from the gain module to the plane mirror, shortening the total length of the laser amplification system, and facilitating the miniaturization of the laser amplification system. Simultaneously, the planar mirror configuration allows control of the laser beam waist position in the laser amplification system, ensuring the laser has a smaller radius of curvature when reaching the first reflecting surface, simplifying the processing and manufacturing of the first reflecting surface, and enabling self-reproduction of the laser within the laser amplification system.

[0007] When a laser beam is amplified multiple times within a laser amplification system, it passes through the gain module multiple times. This results in multiple overlapping beams at the gain module, which can easily lead to a thermal lensing effect, affecting the self-reproduction of the laser within the amplification system. By making the second and third reflecting surfaces of the folding mirror perpendicular, the laser beam entering and exiting the folding mirror becomes parallel. This allows for adjustment of the folding mirror's position within the amplification system, altering the optical path length of the laser within the system. This, in turn, compensates for the thermal lensing effect at the gain medium, ensuring the self-reproduction of the laser throughout the entire amplification system.

[0008] In one possible implementation, the number of planar reflectors is twice the number of faceted reflectors. Two planar reflectors form a group, with one reflector in each group receiving the laser emitted from the gain module and reflecting it back to the faceted reflector, and the other reflecting the laser emitted from the faceted reflector back to the gain module. By setting the number of planar reflectors to twice the number of faceted reflectors, the angles of the two planar reflectors in a group can be adjusted independently. This allows one reflector to more accurately reflect the laser to the faceted reflector, and the other to more accurately receive the laser from the faceted reflector.

[0009] In one possible implementation, the first reflecting surface is curved, while the second and third reflecting surfaces are both planar. By making the first reflecting surface curved, the laser light incident on it converges, and the laser light exiting it is also focused, which facilitates self-reproduction of the laser light. By making the second and third reflecting surfaces planar, it is advantageous to coordinate the perpendicularity of the second and third reflecting surfaces, achieving the effect of parallelism between the laser light incident on and exiting the folded mirror.

[0010] In one possible implementation, the laser amplification system includes multiple mirror-reflecting modules spaced apart, with the laser sequentially passing through each module. By including multiple mirror-reflecting modules in the laser amplification system, it is advantageous to achieve optical path folding of the laser and to amplify the laser multiple times by passing through the gain module.

[0011] In one possible implementation, the laser amplification system comprises multiple planar mirrors, with at least some of the planar mirrors having their reflection points located on a first plane; and multiple planar mirrors, with at least some of the planar mirrors having their reflection points located on a second plane, which is parallel to the first plane. By making the second plane parallel to the first plane, it is advantageous to position the laser beam waist at the center point of the laser's optical path propagation within the mirror-reflection module, thereby achieving self-reproduction of the laser at the mirror-reflection module. Simultaneously, it also simplifies the adjustment of the planar mirrors and compensates for the thermal lensing effect at the gain medium.

[0012] In one possible implementation, the laser amplification system satisfies the following relationships: L1 < L2, L1 + L2 = L; where L1 is the vertical distance from the reflection point of the first reflecting surface to the second plane, L2 is the vertical distance from the first plane to the second plane, and L is the sum of the vertical distances from the reflection point of the first reflecting surface to the second plane and the vertical distances from the first plane to the second plane. By ensuring that L2 < L1 in the laser amplification system, the planar reflector is always positioned between the first reflecting surface and the plane reflector, which facilitates the folding of the optical path of the laser light by the planar reflector.

[0013] In one possible implementation, a single mirror-reflecting module includes a single planar reflector and two planar reflectors. The two planar reflectors correspond to the second reflecting surface and the third reflecting surface, respectively. The distance between the reflection points of the second and third reflecting surfaces is D1, and the distance between the reflection points of the two planar reflectors is D2. The mirror-reflecting module satisfies the relationship: D2 = D1. By ensuring that D2 = D1 in the laser amplification system, the spacing between the two planar reflectors in the single mirror-reflecting module is rationally configured, allowing the second reflecting surface to successfully receive the laser reflected from one of the planar reflectors and to successfully reflect the laser to the other planar reflector, thus achieving laser reflection within the mirror-reflecting module.

[0014] In one possible implementation, the laser amplification system includes multiple mirror-reflecting modules arranged in an array. Each mirror-reflecting module includes a first mirror-reflecting module. The minimum distance between the reflection point of the planar mirror in the first mirror-reflecting module and the reflection points of the planar mirrors in other mirror-reflecting modules is D3. The minimum distance between the reflection point of the plane mirror in the first mirror-reflecting module and the reflection point of the plane mirror in other mirror-reflecting modules is D4. The mirror-reflecting modules satisfy the relationship: D1 = D2 = D3 = D4. By ensuring that the laser amplification system satisfies D1 = D2 = D3 = D4, the distribution positions of the multiple plane mirrors and multiple planar mirrors are rationally configured when multiple mirror-reflecting modules are present in the laser amplification system.

[0015] In one possible implementation, the laser amplification system includes multiple mirror-reflecting modules arranged in a ring. At least a portion of the reflective points of the planar mirrors are located on a first circumference, and at least a portion of the reflective points of the plane mirrors are located on a second circumference. The radius of the first circumference is R1, and the radius of the second circumference is R2. The mirror-reflecting modules satisfy the relationship: R1 = R2. By ensuring that R1 = R2 in the laser amplification system, the distribution positions of the multiple planar mirrors and multiple plane mirrors can correspond when the multiple mirror-reflecting modules are arranged in a ring, which is beneficial for achieving laser reflection within the mirror-reflecting modules.

[0016] In a possible implementation, at least part of the reflective points of the folded mirror are located on the third circumference, and at least part of the reflective points of the plane mirror are located on the fourth circumference. The center of the third circumference coincides with the center of the first circumference, and the center of the fourth circumference coincides with the center of the second circumference. The radius of the third circumference is R3, and the radius of the fourth circumference is R4. The mirror reflection module satisfies the relation: R3 = R4. By making the laser amplification system satisfy R3 = R4, when multiple mirror reflection modules are arranged in a ring, the distribution positions of multiple folded mirrors and multiple plane mirrors can correspond to each other, which is beneficial to realizing the folding-back of the laser in the mirror reflection module.

[0017] In a possible implementation, in the direction of the straight line where the reflective points of two plane mirrors are located, the length of a single plane mirror is D0, and the plane mirror satisfies the relation: D0 < D2. By making the laser amplification system satisfy D0 < D2, the size of the plane mirror and the interval distance between multiple plane mirrors are reasonably configured, which is beneficial to realizing the folding-back of the laser in the mirror reflection module and facilitating the individual adjustment of multiple plane mirrors.

[0018] In a possible implementation, the laser amplifier further includes a polarization beam splitter, a retroreflector, and a polarization converter. The polarization beam splitter, the retroreflector, and the polarization converter are located on the reflection side of the gain module. The polarization converter is located between the gain module and the retroreflector. The polarization converter is used to change the polarization state of the laser. The polarization beam splitter is located at the incident end of the laser amplification system. The retroreflector is used to vertically reflect the laser transmitted by the gain module. The polarization converter is located between the retroreflector and the gain module.

[0019] By making the laser amplifier further include a polarization beam splitter, a retroreflector, and a polarization converter, after the laser passes through the first optical path and the second optical path, the laser passes through the gain module 4 times in the laser amplification system, realizing 8 - fold amplification, which is beneficial to reducing the overall volume of the laser amplification system and also beneficial to reducing the setting cost of the laser amplification system.

[0020] In a possible implementation, the laser amplification system further includes a displacement mechanism. The displacement mechanism is connected to the folded mirror and is used to drive the folded mirror to move in the vertical direction from the gain module to the plane mirror.

[0021] By making the laser amplification system further include a displacement mechanism, it can drive the folded mirror to move along the optical axis direction to change the optical path of the laser in the laser amplification system, thereby compensating the thermal lens effect at the gain medium and ensuring the self - reproduction of the laser in the entire laser amplification system.

[0022] Secondly, this application also provides a laser amplifier, including a pump source, a seed laser, and a laser amplification system as described in any one of the embodiments of the first aspect. The pump source is used to provide pump energy to the gain medium of the laser amplification system, and the seed laser is located on the reflection side of the gain module of the laser amplification system and is used to emit incident laser light into the gain module. The beneficial effects in this embodiment are similar to those in the above embodiments, and will not be described again in this embodiment.

[0023] In one possible implementation, the laser amplifier further includes a control board electrically connected to both the pump source and the seed source. The control board controls the pump source to provide pump energy to the gain medium and also controls the seed source to emit incident laser light into the gain module. By including a control board in the laser amplifier, it is advantageous to adjust the pump energy and incident laser intensity via the control board.

[0024] Thirdly, this application also provides a laser processing apparatus, including a beam splitter and a laser amplifier as described in any of the embodiments of the second aspect above. The gain module of the laser amplifier is used to reflect the incident laser into an outgoing laser. The beam splitter is located on the reflection side of the gain module and is used to receive and split the outgoing laser. The beneficial effects in this embodiment are similar to those in the above embodiments, and will not be described again in this embodiment.

[0025] In one possible implementation, the laser processing equipment further includes a focusing lens located on the beam-splitting side of the beam splitter. The beam splitter splits the emitted laser beam into a first beam and a second beam, and the focusing lens receives the first beam and focuses it onto the workpiece. Including a focusing lens in the laser processing equipment improves its processing efficiency. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the laser amplification system provided in the embodiments of this application;

[0027] Figure 2 yes Figure 1 A schematic diagram of the laser beam in the laser amplification system provided in the illustrated embodiment;

[0028] Figure 3 yes Figure 1 A top view of the laser amplification system provided in the embodiment shown;

[0029] Figure 4 This is a schematic diagram of the structure of the laser amplification system provided in the first embodiment of this application;

[0030] Figure 5 This is a schematic diagram of the distribution of the mirror reflection module provided in the first embodiment of this application;

[0031] Figure 6 This is a schematic diagram of the structure of the laser amplification system provided in the second embodiment of this application;

[0032] Figure 7 This is a schematic diagram of the distribution of the mirror reflection module provided in the second embodiment of this application;

[0033] Figure 8 This is a schematic diagram of the structure of the laser amplification system provided in the third embodiment of this application;

[0034] Figure 9 This is a schematic diagram of the distribution of the mirror reflection module provided in the third embodiment of this application;

[0035] Figure 10 This is a schematic diagram of another laser amplification system provided in the embodiments of this application;

[0036] Figure 11 yes Figure 10 The diagram shows a first optical path in the embodiment shown.

[0037] Figure 12 yes Figure 10 The diagram shows the second optical path in the embodiment shown.

[0038] Figure 13 This is a schematic diagram of a laser amplifier system provided in an embodiment of this application;

[0039] Figure 14 This is a schematic diagram of the laser processing system provided in the embodiments of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 10-Gain module; 11-First reflecting surface; 12-Laser self-gain medium;

[0042] 100-Laser Amplification System;

[0043] 20 - Mirror module; 21 - Folded mirror; 22 - Plane mirror; 23 - Incident mirror; 24 - Outgoing mirror; 25 - Polarizing beam splitter; 26 - Reverse mirror; 27 - Polarization converter;

[0044] 200 - Laser amplifier; 201 - Seed source; 202 - Pump source; 203 - Control board; 211 - Second reflecting surface; 212 - Second reflecting surface; 213 - First plane; 221 - Fourth reflecting surface; 222 - Fifth reflecting surface; 223 - Second plane;

[0045] 300 - Laser processing equipment; 301 - Beam splitter; 302 - Workpiece; 303 - Focusing lens; 304 - Total reflection mirror. Detailed Implementation

[0046] The embodiments of this application are described below with reference to the accompanying drawings.

[0047] For ease of understanding, the English abbreviations and related technical terms used in the embodiments of this application will be explained and described below.

[0048] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0049] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0050] It should be understood that the term "and / or" used in this document is merely a description of the same field in the related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0051] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0052] It should be understood that the terms "first," "second," etc., used in this application are for distinguishing purposes only and should not be construed as indicating or implying relative importance or order.

[0053] In the description of this application, the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0054] The phrase "within the range" used in this application, unless otherwise specified, includes both endpoints of the range by default. For example, in the range of 1 to 5, it includes the values ​​1 and 5.

[0055] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "connection" and "joining" should be interpreted broadly, for example, they can be fixed connections, detachable connections, mating connections or integral connections; those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0056] Linearly polarized light refers to light whose light vector vibrates along only one fixed direction, and the vibration of the light vector lies in a single plane along the direction of light propagation. Linearly polarized light can have different polarization modes, such as first-state linearly polarized light and second-state linearly polarized light. The vibration directions of first-state and second-state linearly polarized light are different; for example, first-state linearly polarized light can be P-polarized light, and second-state linearly polarized light can be S-polarized light. The vibration directions of P-polarized light and S-polarized light are perpendicular. It is understood that this embodiment is only for distinguishing different modes of linearly polarized light; "first" and "second" do not constitute a limitation on the mode of linearly polarized light. First-state linearly polarized light can also be S-polarized light, and second-state linearly polarized light can also be P-polarized light.

[0057] Circularly polarized light refers to light whose electric vector traces a circular path along the direction of light propagation. Circularly polarized light has different polarization forms, such as first-state circularly polarized light and second-state circularly polarized light. The rotation directions of first-state and second-state circularly polarized light are different; for example, first-state circularly polarized light can be right-handed circularly polarized light, while second-state circularly polarized light can be left-handed circularly polarized light. Viewed towards the light source, light with a clockwise rotating electric vector is called right-handed circularly polarized light, and light with a counter-clockwise rotating electric vector is called left-handed circularly polarized light. It is understood that in this embodiment, to distinguish only the different forms of circularly polarized light, "first" and "second" do not constitute a limitation on the form of circularly polarized light; first-state circularly polarized light can also be left-handed circularly polarized light, and second-state circularly polarized light can also be right-handed circularly polarized light.

[0058] The laser emitted by the laser is a Gaussian beam, and its equiphase surface is always spherical. The center of curvature of the equiphase surface changes continuously during propagation, and the amplitude and intensity on the equiphase surface always maintain a Gaussian distribution. The spot size of the laser changes continuously at different optical path lengths, with the smallest spot size being the beam waist. At this point, the Gaussian beam propagates in parallel, and the radius of curvature of the equiphase surface is infinite. In a laser amplification system, the laser is amplified after passing through the gain medium. Multiple plane mirrors are used in the laser amplification system, causing the laser to be reflected multiple times through the gain medium, thus achieving multiple amplifications of the laser.

[0059] If the laser is allowed to propagate almost freely in the laser amplification system, the spot size of the laser beam changes significantly each time it passes through the gain medium. This results in poor consistency of the laser spot size at the gain medium, degrading the efficiency, beam quality, stability, and other performance characteristics of the laser amplifier output laser.

[0060] To ensure consistent laser spot size across the gain medium and achieve self-reproduction of the laser at the gain medium, the laser beam waist position must be strictly controlled at the plane mirror. This ensures parallel laser transmission at the plane mirror, with a certain distance between the laser beam waist and the gain medium to guarantee a certain number of amplifications. Simultaneously, the gain medium should exhibit weak focusing to keep the laser beam waist position controlled at the plane mirror. Strong focusing at the gain medium would place the laser beam waist between the gain medium and the plane mirror, preventing self-reproduction at the gain medium. Weak focusing at the gain medium results in a larger radius of curvature, making the gain medium increasingly planar, leading to higher manufacturing costs and greater manufacturing difficulty.

[0061] This application provides a laser amplification system 100, see reference. Figure 1 As shown, Figure 1 A schematic diagram of a laser amplification system 100 according to this application is shown. The laser amplification system 100 receives incident laser light and amplifies it before outputting it as an outgoing laser beam. The incident laser undergoes multiple reflections within the laser amplification system 100, and is amplified multiple times during these reflections, resulting in a gradual increase in laser power. That is, the power of the outgoing laser is greater than the power of the incident laser, while simultaneously ensuring the beam quality of the output laser. The incident laser can be a continuous laser or a pulsed laser.

[0062] The laser amplification system 100 includes a gain module 10 and a mirror reflection module 20. The mirror reflection module 20 is located on the side of the gain module 10 closer to the laser, and the mirror reflection module 20 and the gain module 10 are spaced apart. The gain module 10 is used to amplify the laser, and the mirror reflection module 20 is used to realize multiple reflections of the laser, realize the folding of the optical path of the laser, and make the laser pass through the gain module 10 multiple times to achieve multiple amplification of the laser.

[0063] The gain module 10 has a first transmitting surface and a first reflecting surface 11. The first transmitting surface is used to transmit laser light, and the first reflecting surface 11 is used to reflect laser light. When laser light enters the gain module 10, the laser light first passes through the first transmitting surface, and then enters the first reflecting surface 11 from the first transmitting surface in the direction of the first reflecting surface 11. The first reflecting surface 11 is curved and concave towards the side away from the first transmitting surface, so that the first reflecting surface 11 is a concave reflecting surface relative to the laser light. The first reflecting surface 11 converges the laser light entering the first reflecting surface 11 and causes the laser light exiting the first reflecting surface 11 to be beamed.

[0064] The curvature center of the first reflecting surface 11 coincides with the curvature center of the equiphase surface of the laser at the first reflecting surface 11, so that the laser spot size at the first reflecting surface 11 is equal to the laser spot size after being reflected by the first reflecting surface 11. This avoids the laser spot size changing after being reflected by the first reflecting surface 11, which is beneficial to realizing the self-reproduction of the laser at the first reflecting surface 11.

[0065] The gain module 10 also includes a gain medium 12, which is located between the first reflecting surface 11 and the first transmitting surface. The gain medium 12 is positioned such that the first reflecting surface 11 is concave towards the first reflecting surface 11 from the gain medium 12. The surface of the gain medium 12 facing away from the first reflecting surface 11 serves as the laser incident surface of the gain module 10, allowing the gain medium 12 to enter the first reflecting surface 11 towards it. The gain medium 12 is a sheet-like solid gain medium, which has good heat dissipation performance, low thermal effect, and weak nonlinear effect. When the laser enters the gain module 10, it is first amplified by the gain medium 12, then reflected by the first reflecting surface 11. The laser reflected by the first reflecting surface 11 is amplified a second time by the gain medium 12, resulting in the laser being amplified twice in a single pass through the gain module 10. In one embodiment, the gain module 10 includes a concave mirror with a first reflecting surface 11. The gain medium 12 is distributed on the concave mirror and located on the side of the first reflecting surface 11 closest to the laser.

[0066] The mirror reflection module 20 is located on the reflection side of the gain module 10. The mirror reflection module 20 includes a plane mirror 22 and a folded mirror 21. The folded mirror 21 is located between the gain module 10 and the plane mirror 22. The laser undergoes multiple reflections between the plane mirror 22 and the folded mirror 21, causing the optical path of the laser from the gain module 10 to the plane mirror 22 and then from the plane mirror 22 back to the gain module 10 to be folded by the folded mirror 21.

[0067] Under the premise of satisfying the self-reproduction of the laser at the gain module 10, when the laser optical path is not folded, the distance from the laser self-gain module 10 to the plane mirror 22 is the same as the distance from the laser self-gain module 10 to the laser beam waist. When the laser optical path is folded, the distance from the laser self-gain module 10 to the plane mirror 22 plus the distance from the laser from the plane mirror 22 to the folded mirror 21 is approximately equal to the distance from the laser self-gain module 10 to the laser beam waist. Since the folded mirror 21 is located between the gain module 10 and the plane mirror 22, the vertical distance from the gain module 10 to the plane mirror 22 is reduced by approximately the distance from the laser from the plane mirror 22 to the folded mirror 21 after the laser optical path is folded, which shortens the total length of the laser amplification system 100 and is conducive to achieving the miniaturization requirement of the laser amplification system 100. At the same time, the reduction of the air gap in the laser amplification system 100 reduces the fluctuation of the laser during propagation, which is beneficial to improving the stability of the laser amplification system 100.

[0068] In one embodiment, the laser amplification system 100 further includes an incident reflector 23 and an exit reflector 24. The incident reflector 23 is used to reflect the incident laser and adjust the angle of the incident laser so that the incident laser can accurately enter the gain module 10. The exit reflector 24 is used to reflect the exit laser and adjust the angle of the exit laser so that the exit laser can exit the laser amplification system 100 at the required angle.

[0069] Please see Figure 2 , Figure 2 This is a schematic diagram of the laser beam in the laser amplification system 100. When the laser enters the laser amplification system 100, it first enters the gain module 10. As the laser propagates toward the gain module 10, it gradually diverges, meaning that the radius of curvature of the equiphase surface of the laser decreases continuously from infinity. As the laser optical path increases, the radius of curvature of the equiphase surface of the laser decreases. The center of curvature of the first reflecting surface 11 coincides with the center of curvature of the equiphase surface of the laser at the first reflecting surface 11, giving the first reflecting surface 11 a certain radius of curvature. The first reflecting surface 11 has strong focusing ability, a small radius of curvature, and a greater degree of curvature, which is more conducive to simplifying the processing and manufacturing of the gain module 10.

[0070] The first reflecting surface 11 converges the laser light incident upon it and causes the laser light exiting the first reflecting surface 11 to be beamed. Due to the characteristics of its Gaussian beam, the laser light emitted from the first reflecting surface 11 will first converge and then diverge during propagation. The point where the beam converges and propagates parallel is called the laser beam waist. The positions of the plane mirror 22 and the folded mirror 21 in the mirror reflection module 20 are adjusted so that the laser beam waist is located at the center point of the optical path of the laser light propagating within the mirror reflection module 20, thereby achieving self-reproduction of the laser light at the mirror reflection module 20.

[0071] The laser emitted from the mirror-reflecting module 20 re-enters the gain module 10. Since the beam waist of the laser emitted from the first reflecting surface 11 is within the mirror-reflecting module 20, the laser emitted from the mirror-reflecting module 20 gradually diverges as it propagates toward the gain module 10. That is, the radius of curvature of the equiphase surface of the laser continuously decreases from infinity, so that the laser emitted from the mirror-reflecting module 20 has a certain curvature when it reaches the first reflecting surface 11, and the center of curvature of the first reflecting surface 11 coincides with the center of curvature of the laser at the first reflecting surface 11, thus realizing the self-reproduction of the laser at the first reflecting surface 11.

[0072] When the laser enters the laser amplification system 100, it passes through the gain module 10 for the first time, achieving a cumulative amplification of the laser twice. When the laser exits from the mirror reflection module 20, it passes through the gain module 10 for the second time, achieving a cumulative amplification of the laser four times. By changing the number of mirror reflection modules 20 in the laser amplification system 100, the laser entering the laser amplification system 100 can pass through the gain module 10 multiple times and achieve multiple amplifications of the laser, which is beneficial to improving the amplification capability of the laser amplification system 100.

[0073] The pump source provides pump energy to the gain medium 12 in the laser amplification system 100 based on the applied signal. After absorbing the pump energy, the gain medium 12 achieves population inversion. When the laser passes through the gain medium 12 in a population-inverted state, it undergoes stimulated emission amplification, thereby increasing the laser power. During the operation of the laser amplification system 100, the gain medium 12 continuously absorbs pump energy, which can easily lead to a thermal lensing effect. The temperature at the gain medium 12 gradually increases, and thermal deformation occurs on the crystal surface of the gain medium 12, resulting in different crystal distribution densities at different locations. This affects the amplification effect of the laser and the consistency of the laser spot size at the gain module 10. At the same time, when the laser entering the laser amplification system 100 passes through the gain module 10 multiple times, multiple overlapping spots exist at the gain medium 12, which can further enhance the thermal lensing effect at the gain medium 12, affecting the self-reproduction of the laser at the gain module 10.

[0074] In the mirror reflection module 20, the planar reflector 21 receives the laser light emitted from the plane reflector 22 and deflects its propagation direction before emitting it. The laser light emitted from the planar reflector 21 is then received by the plane reflector 22. Changing the vertical distance between the planar reflector 21 and the plane reflector 22 alters the optical path length of the laser light within the mirror reflection module 20, i.e., changes the optical path length of the laser light within the entire laser amplification system 100. When the position and angle of the plane reflector 22 remain constant, and the planar reflector 21 moves closer to the gain module 10, the distance between the planar reflector 21 and the plane reflector 22 increases, thus increasing the optical path length of the laser light within the mirror reflection module 20, and consequently, the optical path length of the laser light within the entire laser amplification system 100.

[0075] The planar reflector 21 includes a second reflecting surface 211 and a second reflecting surface 212. Both the second reflecting surface 211 and the second reflecting surface 212 are located on the side of the planar reflector 21 facing the plane reflector 22, and the second reflecting surface 211 and the second reflecting surface 212 are perpendicular to each other, so that the laser light entering the planar reflector 21 and the laser light emanating from the planar reflector 21 are parallel. Therefore, when the position of the planar reflector 21 in the laser amplification system 100 is adjusted, the laser light entering the planar reflector 21 and the laser light emanating from the planar reflector 21 always remain parallel, avoiding directional deviation of the laser light during the adjustment process, which would affect the normal operation of the laser amplification system 100. At the same time, adjusting the position of the planar reflector 21 in the laser amplification system 100 also helps to compensate for the thermal lensing effect at the gain medium 12 by changing the optical path of the laser light throughout the laser amplification system 100, thus ensuring the self-reproduction of the laser light throughout the laser amplification system 100.

[0076] For example, both the second reflecting surface 211 and the second reflecting surface 212 are planar, and the folded reflector 21 includes, but is not limited to, a right-angle prism and a cubic pyramidal prism.

[0077] The number of plane mirrors 22 is twice the number of planar mirrors 21. Two plane mirrors 22 form a group, and the two plane mirrors 22 in the same group are spaced apart and can be adjusted independently. A single planar mirror 21 corresponds to a single group of plane mirrors 22, that is, a single planar mirror 21 corresponds to two plane mirrors 22. One of the two plane mirrors 22 in the same group is used to receive the laser emitted from the gain module 10 and reflect it to the planar mirror 21, and the other is used to receive the laser emitted from the planar mirror 21 and reflect it to the gain module 10.

[0078] Please see Figure 1 and Figure 3For example, two plane mirrors 22 in the same group have a fourth reflecting surface 221 and a fifth reflecting surface 222, respectively. The fourth reflecting surface 221 and the fifth reflecting surface 222 are both located on the side of the plane mirror 22 facing the gain module 10. The fourth reflecting surface 221 corresponds to the second reflecting surface 211, and the fifth reflecting surface 222 corresponds to the second reflecting surface 212. When the incident laser enters the laser amplification system 100, the first reflecting surface 11 of the gain module 10 receives the incident laser and reflects it into a first laser; the fourth reflecting surface 221 of the plane mirror 22 receives the first laser and reflects it into a second laser; the folded mirror 21 receives the second laser and reflects it into a third laser. The second reflecting surface 211 receives the second laser reflected by the fourth reflecting surface 221 and deflects the light path of the second laser to the second reflecting surface 212. The second reflecting surface 212 receives the second laser reflected by the second reflecting surface 211 and reflects it into a third laser; the fifth reflecting surface 222 of the plane mirror 22 receives the third laser and reflects it into a fourth laser to the gain module 10; the first reflecting surface 11 of the gain module 10 receives the fourth laser. The first reflecting surface 11 can reflect the fourth laser as an output laser exiting the laser amplification system 100, or it can reflect the fourth laser as a sixth laser to another mirror module 20.

[0079] Please see Figure 2 and Figure 3 When a laser beam enters the laser amplification system 100, it is first reflected by the incident mirror 23 and then enters the gain module 10. From the gain module 10, it enters the mirror reflection module 20, passing sequentially through the fourth reflecting surface 221, the second reflecting surface 211, the second reflecting surface 212, and the fifth reflecting surface 222. It then returns to the gain module 10 via the fifth reflecting surface 222, and from the gain module 10, it enters the exit mirror 24 before exiting the laser amplification system 100. The laser beam gradually diverges as it propagates from the incident mirror 23 towards the gain module 10. The beam waist of the laser beam is located in the optical path from the second reflecting surface 211 towards the second reflecting surface 212. The laser beam gradually converges as it propagates from the gain module 10 towards the second reflecting surface 211, and gradually diverges as it propagates from the second reflecting surface 212 towards the gain module 10. The laser beam gradually converges as it propagates from the gain module 10 towards the exit mirror 24, thus achieving self-reproduction of the laser beam at the mirror reflection module 20.

[0080] Only a single light spot exists on the second reflecting surface 211 and the second reflecting surface 212 of the planar reflector 21, and on the fourth reflecting surface 221 and the fifth reflecting surface 222 of the planar reflector 22. This simplifies the arrangement of the planar reflector 21 and the planar reflector 22, and avoids the thermal effect caused by multiple overlapping light spots on the planar reflector 21 or the planar reflector 22, which would affect the laser beam quality and damage the planar reflector 21 or the planar reflector 22.

[0081] For one possible implementation, please refer to Figure 4 The laser amplification system 100 has multiple mirror reflection modules 20. Each mirror reflection module 20 includes a single planar reflector 21 and two plane reflectors 22. The multiple mirror reflection modules 20 are arranged at intervals, so that the multiple planar reflectors 21 belonging to different mirror reflection modules 20 are arranged at intervals, and the multiple plane reflectors 22 belonging to different mirror reflection modules 20 are arranged at intervals. This helps to simplify the arrangement of the planar reflectors 21 and plane reflectors 22 in the laser amplification system 100 and avoids mutual interference between the planar reflectors 21 and plane reflectors 22.

[0082] In the laser amplification system 100, the laser passes through multiple mirror reflection modules 20 in sequence, so that the laser is reflected multiple times by the multiple mirror reflection modules 20 to the gain module 10, thereby realizing multiple amplification of the laser and improving the power and beam quality of the laser.

[0083] When the laser beam enters the laser amplification system 100, it first passes through the gain module 10. During its subsequent path, a single mirror module 20 reflects the laser beam, causing it to return to the gain module 10 only once. Therefore, the number of times the laser beam passes through the gain module 10, excluding its initial entry into the laser amplification system 100, is equal to the number of mirror modules 20. Thus, if the number of mirror modules 20 in the laser amplification system 100 is n, then the number of planar mirrors 21 is n, the number of plane mirrors 22 is n, the number of times the laser beam passes through the gain module 10 in the laser amplification system 100 is n+1, and the number of times the laser beam is amplified in the laser amplification system 100 is 2(n+1).

[0084] The laser amplification system 100 has multiple mirror modules 20, thus it has multiple planar reflectors 21 and multiple flat reflectors 22. Taking the point on the second reflecting surface 211 that receives and reflects the laser as the reflection point of the second reflecting surface 211, and the point on the second reflecting surface 212 that receives and reflects the laser as the reflection point of the second reflecting surface 212, then a single planar reflector 21 has two reflection points. Similarly, taking the point on the fourth reflecting surface 221 that receives and reflects the laser as the reflection point of the fourth reflecting surface 221, and the point on the fifth reflecting surface 222 that receives and reflects the laser as the reflection point of the fifth reflecting surface 222, then a single flat reflector 22 has one reflection point. Therefore, multiple planar reflectors 21 have multiple reflection points, and multiple flat reflectors 22 have multiple reflection points.

[0085] In the laser amplification system 100, at least some of the reflective points of the planar mirrors 21 are located on the first plane 213, and at least some of the reflective points of the plane mirrors 22 are located on the second plane 223. The second plane 223 is parallel to the first plane 213. The laser light entering the planar mirrors 21 and the laser light exiting the planar mirrors 21 are parallel and perpendicular to the first plane 213 and the second plane 223, so that in the same mirror reflection module 20 and different mirror reflection modules 20, the optical path of the laser light entering the planar mirrors 21 from the plane mirrors 22 and the optical path of the laser light entering the planar mirrors 22 from the planar mirrors 21 are equal, so that the beam waist of the laser light is located at the center point of the optical path of the laser light propagating in the mirror reflection module 20, thereby realizing the self-reproduction of the laser light in the mirror reflection module 20. Meanwhile, when adjusting the folded mirror 21, the first plane 213 is always kept perpendicular to the second plane 223, and the laser light entering the folded mirror 21 and the laser light exiting the folded mirror 21 are always kept parallel, thus avoiding the laser direction deviation during the adjustment process, which would affect the normal operation of the laser amplification system 100.

[0086] The first reflecting surface 11 of the gain module 10 is a concave reflecting surface. The central axis of the first reflecting surface 11 passes through the center of curvature and the focal point of the first reflecting surface 11. The central axis of the first reflecting surface 11 is the optical axis of the laser amplification system 100. The first plane 213 and the second plane 223 are both perpendicular to the optical axis. The laser light entering the folded mirror 21 and the laser light exiting the folded mirror 21 are parallel, and both the laser light entering the folded mirror 21 and the laser light exiting the folded mirror 21 are parallel to the optical axis. The distance between the first reflecting surface 11 and the folded mirror 21 on the optical axis is the perpendicular distance between the first reflecting surface 11 and the folded mirror 21. The distance between the folded mirror 21 and the plane mirror 22 on the optical axis is the perpendicular distance between the folded mirror 21 and the plane mirror 22. That is, the total optical length of the laser amplification system is the distance between the first reflecting surface 11 and the plane mirror 22 on the optical axis.

[0087] When the laser amplification system 100 includes multiple mirror modules 20, the multiple planar mirrors 22 can be arranged in an array, corresponding to the multiple planar mirrors 21 arranged in an array; alternatively, the multiple planar mirrors 22 can be arranged in a ring, corresponding to the multiple planar mirrors 21 arranged in an array. In one embodiment, the reflection points of the multiple planar mirrors 21 are all located on a first plane 213, and the reflection points of the multiple planar mirrors 22 are all located on a second plane 223.

[0088] For one possible implementation, please refer to Figure 3The laser amplification system 100 satisfies the following relationship: L2 < L1, L1 + L2 = L; where L1 is the vertical distance from the reflection point of the first reflecting surface 11 to the second plane, L2 is the vertical distance from the first plane 213 to the second plane 223, and L is the sum of the vertical distances from the reflection point of the first reflecting surface 11 to the second plane 223 and from the first plane 213 to the second plane 223.

[0089] The vertical distance from the reflection point of the first reflecting surface 11 to the second plane is approximately equal to the distance from the first reflecting surface 11 to the plane mirror 22 on the optical axis. The vertical distance from the first plane 213 to the second plane 223 is approximately equal to the distance from the folded mirror 21 to the plane mirror 22 on the optical axis. The sum of the vertical distances from the reflection point of the first reflecting surface 11 to the second plane 223 and from the first plane 213 to the second plane 223 is approximately equal to the optical path length traversed by the laser in a single pass through the gain medium 12.

[0090] By ensuring that the laser amplification system 100 satisfies L2 < L1, the vertical distance from the first plane 213 to the second plane 223 is less than the vertical distance from the reflection point of the first reflecting surface 11 to the second plane, thus ensuring that the folded reflector 21 is always located between the first reflecting surface 11 and the plane reflector 22, thereby achieving the folding of the optical path of the laser by the folded reflector 21.

[0091] For one possible implementation, please refer to Figure 5 and Figure 7 A single mirror-reflecting module 20 includes a single folded mirror 21 and two plane mirrors 22. The two plane mirrors 22 correspond to the second reflecting surface 211 and the second reflecting surface 212, respectively. The distance between the reflection point of the second reflecting surface 211 and the reflection point of the second reflecting surface 212 is D1, and the distance between the reflection points of the two plane mirrors 22 is D2. The mirror-reflecting module 20 satisfies the relationship: D2 = D1.

[0092] By making the laser amplification system 100 satisfy the above relationship, the spacing between the two plane mirrors 22 in the single mirror reflection module 20 is reasonably configured, so that the second reflecting surface 211 can successfully receive the laser reflected from one of the plane mirrors, and the second reflecting surface 212 can successfully reflect the laser to the other plane mirror, thus realizing the reflection of the laser in the mirror reflection module 20.

[0093] For one possible implementation, please refer to Figure 6 and Figure 7The laser amplification system 100 includes multiple mirror reflection modules 20, meaning that the laser amplification system 100 includes three or more mirror reflection modules 20. The multiple mirror reflection modules 20 are arranged in an array around a central point to meet the miniaturization requirement of the laser amplification system 100. Compared to arranging multiple mirror reflection modules 20 in a straight line, this reduces the space occupied by the multiple mirror reflection modules 20.

[0094] The mirror reflection module 20 includes a first mirror reflection module 20. The minimum distance between the reflection point of the folded mirror 21 of the first mirror reflection module 20 and the reflection point of the folded mirror 21 of other mirror reflection modules 20 is D3. The minimum distance between the reflection point of the plane mirror 22 of the first mirror reflection module 20 and the reflection point of the plane mirror 22 of other mirror reflection modules 20 is D4. The mirror reflection module 20 satisfies the following relationship: D1=D2=D3=D4.

[0095] By ensuring that the laser amplification system 100 satisfies the above-mentioned relationship, when multiple mirror reflection modules 20 exist in the laser amplification system 100, the distribution positions of multiple planar mirrors 22 and multiple folded mirrors 21 are rationally configured, reducing the space occupied by multiple mirror reflection modules 20 and achieving the requirement of miniaturization of the laser amplification system 100; at the same time, the rationally configured spacing between multiple mirror reflection modules 20 also facilitates the sequential propagation of laser light among multiple mirror reflection modules 20.

[0096] For one possible implementation, please refer to Figure 8 and Figure 9 The laser amplification system 100 includes multiple mirror-reflecting modules 20, meaning the laser amplification system 100 includes three or more mirror-reflecting modules 20. The multiple mirror-reflecting modules 20 are arranged in a ring, with at least some of the reflective points of the planar mirrors 21 located on the first circumference, and correspondingly, at least some of the reflective points of the plane mirrors 22 located on the second circumference. The line connecting the centers of the first and second circumferences is parallel to the optical axis. The radius of the first circumference is R1, and the radius of the second circumference is R2; the mirror-reflecting modules 20 satisfy the relationship: R1 = R2.

[0097] By making the mirror reflection module 20 satisfy the above relationship, when multiple mirror reflection modules 20 are arranged in a ring, the distribution positions of multiple folded reflectors 21 and multiple planar reflectors 22 can correspond, which is beneficial to realizing the reflection of laser in the mirror reflection module 20.

[0098] At least some of the reflective points of the planar mirrors 21 are located on the third circumference, and correspondingly, at least some of the reflective points of the planar mirrors 22 are located on the fourth circumference. The straight line containing the centers of the third and fourth circumferences is parallel to the optical axis. The center of the third circumference coincides with the center of the first circumference, and the center of the fourth circumference coincides with the center of the second circumference. In one embodiment, the radius of the third circumference is larger than the radius of the first circumference, and the radius of the fourth circumference is larger than the radius of the second circumference, so that the multiple planar mirrors 21 are arranged in multiple concentric rings, and correspondingly, the multiple planar mirrors 22 are arranged in multiple concentric rings.

[0099] The radius of the third circle is R3, and the radius of the fourth circle is R4; the mirror reflection module 20 satisfies the relationship: R3 = R4. By making the mirror reflection module 20 satisfy the above relationship, when multiple mirror reflection modules 20 are arranged in a ring, the distribution positions of multiple folded reflectors 21 and multiple planar reflectors 22 can correspond, which is beneficial to realizing the reflection of laser in the mirror reflection module 20.

[0100] For one possible implementation, please refer to Figure 7 and Figure 9 In the straight line direction along which the reflection points of the two plane mirrors 22 lie, the length of a single plane mirror 22 is D0, and the plane mirror 22 satisfies the relationship: D0 <D2。

[0101] By making the plane mirror 22 satisfy the above relationship, the size of the plane mirror 22 and the spacing between the multiple plane mirrors 22 can be reasonably configured, which is beneficial to realize the reflection of the laser in the mirror module 20, and also facilitates the individual adjustment of the multiple plane mirrors 22.

[0102] The laser spot is circular with a diameter less than D0. The spot at the plane mirror 22 is located in the central region of the plane mirror 22. The distance between the spot and the four edges of the plane mirror 22 is evenly distributed to enable the plane mirror 22 to receive and reflect the laser.

[0103] For one possible implementation, please refer to Figure 10 The laser amplification system 100 also includes an incident mirror 23, a polarizing beam splitter 25, a retroreflector 26, and a polarization converter 27. The incident mirror 23, the polarizing beam splitter 25, the retroreflector 26, and the polarization converter 27 are all located on the reflection side of the gain module 10. The polarization converter 27 is located between the gain module 10 and the retroreflector 26. The polarizing beam splitter 25 is located at the incident end of the laser amplification system 100. The retroreflector 26 is used to vertically reflect the laser transmitted by the gain module 10. The polarization converter 27 is located between the retroreflector 26 and the gain module 10.

[0104] The polarization converter 27 can be a quarter wave plate (QWP). A wave plate is a thin, parallel-plane sheet made of crystal. The material can be a wafer cut parallel to the optical axis of a birefringent crystal such as quartz or calcite, or it can be made of materials such as mica, cellophane, or polyvinyl alcohol that have a directionality for incident light propagation. Specifically, the wave plate can be bonded to the reflective surface of the retroreflector 26, or it can be bonded separately to a polycarbonate (PC) or glass substrate.

[0105] The polarizing beam splitter 25 includes a polarizing beam splitter element, which can be a thin-film polarizer with polarization selectivity. The thin-film polarizer has a base lens, on one side of which is coated with a polarizing beam splitter film. The thin-film polarizer can achieve the transmission of P-polarized light and the reflection of S-polarized light. The base lens can be made of fused silica.

[0106] When the laser beam enters the laser amplification system 100, it passes through the first and second optical paths. The laser beam follows the same path but travels in opposite directions in the second and first optical paths. Please refer to [link / reference]. Figure 11 The laser beam passes sequentially through a polarizing beam splitter 25, an incident mirror 23, a gain module 10, a mirror reflection module 20, a polarization converter 27, and a reverse mirror 26 in the first optical path; please refer to [link to relevant documentation]. Figure 12 The laser beam passes sequentially through the anti-reflecting mirror 26, polarization converter 27, gain module 10, mirror reflection module 20, gain module 10, incident mirror 23, and polarization beam splitter 25 in the second optical path.

[0107] The incident laser can be a first linearly polarized light, which can be either P-polarized light or S-polarized light. In this embodiment, P-polarized light is used as an example. The polarizing beam splitter 25 is a device that transmits some linearly polarized light and reflects some linearly polarized light. In this embodiment, the polarizing beam splitter 25 can transmit P-polarized light and reflect S-polarized light.

[0108] Referring to Figure 11, in the first optical path, the incident laser first passes through the polarizing beam splitter 25, and then is reflected to the polarization converter 27 where it undergoes a first transformation, changing from linearly polarized light to circularly polarized light (in this embodiment, from P-linearly polarized light to right-handed circularly polarized light), and is then transmitted to the reverse reflector 26. (See Figure 11 for details.) Figure 12As shown, the first circularly polarized light enters the second optical path after passing through the anti-reflector 26. After being reflected at the anti-reflector 26, the first circularly polarized light is reversed and transformed into the second circularly polarized light (in this embodiment, it is transformed from right-handed circularly polarized light to left-handed circularly polarized light). The second circularly polarized light passes through the polarization converter 27 again and is transformed into the second linearly polarized light (in this embodiment, it is transformed from left-handed circularly polarized light to S-line polarized light). When it reaches the polarization beam splitter 25, it is reflected and emitted as the outgoing laser from the laser amplification system 100.

[0109] It should be noted that, Figure 11 and Figure 12 In the diagram, a double-headed arrow tilted from left to right indicates P-polarized light, a double-headed arrow tilted from right to left indicates S-polarized light, a counterclockwise arc-shaped arrow indicates left-handed circularly polarized light, and a clockwise arc-shaped arrow indicates right-handed circularly polarized light.

[0110] The polarizing beam splitter 25 is a polarizing device with polarization direction selectivity, which can selectively transmit first linearly polarized light and reflect second linearly polarized light. The polarization converter 27 is used to change the polarization state of light, and can convert linearly polarized light and circularly polarized light into each other. For example, the incident laser is a first linearly polarized light. The polarization direction of the polarization beam splitter 25 is consistent with the vibration direction of the first linearly polarized light. The first linearly polarized light passes through the polarization beam splitter 25 and is reflected by the incident mirror 23, the gain module 10, and the mirror reflection module 20 to the polarization converter 27 and the reverse mirror 26. The polarization converter 27 converts the first linearly polarized light into a first circularly polarized light. The reverse mirror 26 receives the first circularly polarized light and converts it into a second circularly polarized light before it is emitted. The second circularly polarized light is converted into a second linearly polarized light after passing through the polarization converter 27. The second linearly polarized light is then reflected by the gain module 10, the mirror reflection module 20, and the incident mirror 23 to the polarization beam splitter 25. When the second linearly polarized light passes through the polarization beam splitter 25, the polarization beam splitter 25 reflects the second linearly polarized light, causing the second linearly polarized light to be emitted. That is, the emitted laser is the second linearly polarized light.

[0111] After passing through the first and second optical paths, the laser passes through the gain module 10 four times in the laser amplification system 100, achieving eight amplifications. This eliminates the need to increase the number of mirror modules 20 in the laser amplification system 100, which not only helps to reduce the overall size of the laser amplification system 100 but also helps to reduce the setup cost of the laser amplification system 100.

[0112] For one possible implementation, please refer to Figure 3The laser amplification system 100 also includes a displacement mechanism connected to the folded mirror 21, which is used to move the folded mirror 21 in the vertical direction from the gain module 10 to the plane mirror 22, that is, to move the folded mirror 21 along the optical axis, so as to change the optical path of the laser in the laser amplification system 100, thereby compensating for the thermal lensing effect at the gain medium 12 and ensuring the self-reproduction of the laser in the entire laser amplification system 100.

[0113] In one possible implementation, please refer to Figure 4 and Figure 5 This embodiment provides a laser amplification system 100, which includes a gain module 10, two planar reflectors 21 and four plane reflectors 22.

[0114] Among them, two folded reflectors 21 are distributed at intervals. Reflectors F1 and F2 form one folded reflector 21, and reflectors F3 and F4 form another folded reflector 21. Reflectors F4, F3, F1 and F2 are arranged in a straight line, and there is a gap between reflectors F3 and F1.

[0115] Four plane mirrors 22 are arranged at intervals in sequence. Mirrors M4, M3, M1 and M2 are arranged in a straight line. Mirror M1 corresponds to mirror F1, mirror M2 corresponds to mirror F2, mirror M3 corresponds to mirror F3, and mirror M4 corresponds to mirror F4.

[0116] When the laser enters the laser amplification system 100, the laser passes through the following modules in sequence: gain module 10 → M1 → F1 → F2 → M2 → gain module 10 → M3 → F3 → F4 → M4 → gain module 10. The laser passes through the gain module 10 three times, achieving six amplifications.

[0117] The laser amplification system 100 satisfies the following relationship: d2 = d1; where d1 is the distance between the reflection points of mirror F1 and mirror F2, and d2 is the distance between the reflection points of mirror M1 and mirror M2.

[0118] In the first embodiment, the laser passes through the gain module 10 three times, achieving six amplifications. The diameters of the multiple light spots that reach the gain module 10 three times are all equal, so as to achieve self-reproduction of the laser in the entire laser amplification system 100.

[0119] In one possible implementation, please refer to Figure 6 and Figure 7This embodiment provides a laser amplification system 100, which includes a gain module 10 and eleven mirror modules 20, namely, eleven planar mirrors 21 and twenty-two flat mirrors 22.

[0120] The system comprises multiple folded reflectors 21 spaced apart, including reflectors F1 to F22. Two adjacent reflectors constitute one folded reflector 21. The multiple folded reflectors 21 are arranged in an array, and there are gaps between the multiple folded reflectors 21. The gaps are located in the middle area of ​​the distribution of the multiple folded reflectors 21, so that the laser can enter or exit the laser amplification system 100 from the gaps.

[0121] Multiple planar reflectors 22 are spaced apart. The multiple planar reflectors 22 include reflectors M1 to M22. Reflectors M and F with the same value correspond to each other, so that the multiple planar reflectors 22 are arranged in an array, and there are also gaps between the multiple planar reflectors 22.

[0122] When the laser enters the laser amplification system 100, the laser passes through the following modules in sequence: Gain module 10 → M1 → F1 → F2 → M2 → Gain module 10 → M3 → F3 → F4 → M4 → Gain module 10 → M5 → F5 → F6 → M6 → Gain module 10 → M7 → F7 → F8 → M8 → Gain module 10 → M9 → F9 → F10 → M10 → Gain module 10 → M11 → F11 → F12 → M12 → Gain module 10 → M11 → F11 → F12 → M12 → Gain module 10 → M11 → F11 → F12 → M12 → M11 → M ... Gain Module 10 → M13 → F13 → F14 → M14 → Gain Module 10 → M15 → F15 → F16 → M16 → Gain Module 10 → M17 → F17 → F18 → M18 → Gain Module 10 → M19 → F19 → MF20 → M20 → Gain Module 10 → M21 → F21 → F22 → M22 → Gain Module 10. The laser passes through Gain Module 10 12 times, achieving 24 amplifications.

[0123] The laser amplification system 100 satisfies the following relationship: d1 = d2 = d3 = d4; where d1 is the distance between the reflection points of mirror F1 and mirror F2, d2 is the distance between the reflection points of mirror M1 and mirror M2, d3 is the distance between the reflection points of mirror F2 and mirror F17, and d4 is the distance between the reflection points of mirror M2 and mirror M21.

[0124] In the second embodiment, the laser is amplified 24 times by passing through the 12-gain module 10. The diameters of the multiple light spots that reach the gain module 10 at each of the 12 times are all equal, so as to achieve self-reproduction of the laser in the entire laser amplification system 100.

[0125] In one possible implementation, please refer to Figure 8 and Figure 9 This embodiment provides a laser amplification system 100, which includes a gain module 10 and fifteen mirror modules 20, namely, fifteen planar mirrors 21 and thirty flat mirrors 22.

[0126] The multiple folded mirrors 21 are arranged in a ring, forming two rings with the same center. The multiple folded mirrors 21 include mirrors F1 to F30. Two adjacent mirrors constitute a folded mirror 21. There is a gap between the multiple folded mirrors 21. The gap is located in the middle area of ​​the distribution of the multiple folded mirrors 21, so that the laser can enter or exit the laser amplification system 100 from the gap.

[0127] Multiple plane mirrors 22 include mirrors M1 to M30. Mirrors M and F with the same numerical value correspond to each other, so that the multiple plane mirrors 22 are arranged in a ring. The multiple plane mirrors 22 form two rings with the same center, and there are also gaps between the multiple plane mirrors 22.

[0128] When the laser enters the laser amplification system 100, the laser passes through the following modules in sequence: Gain Module 10 → M1 → F1 → F2 → M2 → Gain Module 10 → M3 → F3 → F4 → M4 → Gain Module 10 → M5 → F5 → F6 → M6 → Gain Module 10 → M7 → F7 → F8 → M8 → Gain Module 10 → M9 → F9 → F10 → M10 → Gain Module 10 → M11 → F11 → F12 → M12 → Gain Module 10 → M13 → F13 → F14 → M14 → Gain Module 10 → M15 → F15 → F16 → M16 → Gain Module 10 → M15 → F15 → F16 → M16 → Gain Module 10 → M15 → F15 → F16 → M16 → M15 → F11 → F12 → F16 → M15 → F11 → F12 → F11 → F11 → F12 → F11 → M12 → Gain Module 10 → M11 → M12 → F11 → F12 → F13 → F13 → F14 → M14 → Gain Module 10 → M15 → F15 → F16 → M16 → M15 → F11 → F12 → F13 → F14 → F14 → M15 → F15 → F16 → M16 → M15 → F11 → F12 → F13 → F14 → F15 → F16 → M15 ...1 → F12 → F12 → F12 → F12 Gain Module 10 → M17 → F17 → F18 → M18 → Gain Module 10 → M19 → F19 → MF20 → M20 → Gain Module 10 → M21 → F21 → F22 → M22 → Gain Module 10 → M23 → F23 → F24 → M24 → Gain Module 10 → M25 → F25 → F26 → M26 → Gain Module 10 → M27 → F27 → F28 → M28 → Gain Module 10 → M29 → F29 → F30 → M30 → Gain Module 10. The laser passes through Gain Module 10 16 times, achieving 32 amplifications.

[0129] The laser amplification system 100 satisfies the following relationships: d1 = d2, r1 = r3, r2 = r4; where d1 is the distance between the reflection points of mirror F1 and mirror F2, d2 is the distance between the reflection points of mirror M1 and mirror M2, r1 is the radius of the circle containing the reflection points of the multiple folded mirrors 21 in the inner ring, r2 is the radius of the circle containing the reflection points of the multiple folded mirrors 21 in the outer ring, r3 is the radius of the circle containing the reflection points of the multiple planar mirrors 22 in the inner ring, and r4 is the radius of the circle containing the reflection points of the multiple planar mirrors 22 in the outer ring.

[0130] In the third embodiment, the laser passes through the gain module 10 16 times, achieving 32 amplifications. The diameters of the multiple light spots that reach the gain module 10 16 times are all equal, so as to achieve self-reproduction of the laser in the entire laser amplification system 100.

[0131] This application also provides a laser amplifier 200, please refer to... Figure 13 The laser amplifier 200 includes a pump source 202, a seed source 201, and the laser amplification system 100 described in any of the above embodiments. The pump source 202 is used to provide pump energy to the gain medium 12 of the laser amplification system 100. The seed source is located on the reflection side of the gain module 10 of the laser amplification system 100 and is used to emit seed laser to the gain module 10 to form incident laser into the laser amplification system 100.

[0132] The laser amplifier 200 also includes a control board 203, which is electrically connected to both the pump source 202 and the seed laser. The control board 203 is also electrically connected to a controller, which sends control signals to the control board 203 to control the seed source 201 and the pump source 202. The control board 203 sends data signals to the controller, enabling the controller to adjust the control signals sent to the control board 203 accordingly. The control board 203 controls the pump source 202 to provide pump energy to the gain medium 12, and also controls the seed laser to emit incident laser light into the gain module 10.

[0133] The control board 203 can also be electrically connected to the displacement mechanism of the laser amplification system 100. The control board 203 is used to control the displacement mechanism to drive the folded reflector 21 to move along the optical axis, so as to change the optical path of the laser in the amplification system and compensate for the thermal lensing effect at the gain medium 12.

[0134] This application also provides a laser processing apparatus 300, please refer to [link / reference]. Figure 14The laser processing equipment 300 includes a beam splitter 301 and a laser amplifier 200 as described in the above embodiment. The gain module 10 of the laser amplifier 200 is used to reflect the incident laser into an outgoing laser, which is an amplified laser after being amplified by the laser amplifier 200. The beam splitter 301 is located on the reflection side of the gain module 10. The beam splitter 301 is used to receive and split the outgoing laser, so that the outgoing laser is divided into multiple lasers.

[0135] The laser processing equipment 300 also includes a focusing lens 303, which is located on the beam splitter side of the beam splitter 301. The beam splitter 301 is used to split the emitted laser into a first beam splitter and a second beam splitter. The focusing lens 303 is used to receive the first beam splitter and focus it onto the workpiece 302.

[0136] In one embodiment, the laser processing equipment 300 includes multiple beam splitters 301 to simultaneously process multiple workpieces 302. The emitted laser beam is split into a first beam splitter and a second beam splitter by the first beam splitter 301. The first beam splitter is received by a focusing lens 303. The second beam splitter continues into the next beam splitter 301, where it is split into a third beam splitter and a fourth beam splitter. The third beam splitter is received by the focusing lens 303, and the fourth beam splitter continues into the next beam splitter 301, and so on.

[0137] In one embodiment, the laser processing equipment 300 further includes a plurality of total reflection mirrors 304, which are located between the laser amplifier 200 and the beam splitter 301, and are used to control the angle of the amplified laser.

[0138] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A laser amplification system, characterized in that, include: A gain module has a first reflective surface and a gain medium stacked together. The first reflective surface is used to reflect laser light. The first reflective surface is recessed from the gain medium toward the first reflective surface. The surface of the gain medium facing away from the first reflective surface is the laser incident surface of the gain module. A mirror-reflecting module, located on the reflecting side of the gain module, includes a plane mirror and a folded mirror. The folded mirror is located between the gain module and the plane mirror. The folded mirror includes a second reflecting surface and a third reflecting surface facing the plane mirror. The second reflecting surface and the third reflecting surface are perpendicular to each other, so as to make the laser light entering the folded mirror and the laser light exiting the folded mirror parallel.

2. The laser amplification system according to claim 1, characterized in that, The number of planar reflectors is twice the number of folded reflectors. Two planar reflectors form a group. One of the planar reflectors in a group is used to receive the laser emitted from the gain module and reflect it to the folded reflector, while the other is used to receive the laser emitted from the folded reflector and reflect it to the gain module.

3. The laser amplification system according to claim 1 or 2, characterized in that, The first reflecting surface is curved, while the second and third reflecting surfaces are both planar.

4. The laser amplification system according to any one of claims 1 to 3, characterized in that, The laser amplification system includes multiple mirror reflection modules, which are spaced apart, and the laser passes through the multiple mirror reflection modules sequentially.

5. The laser amplification system according to claim 4, characterized in that, The laser amplification system has multiple planar reflectors, and at least some of the planar reflectors have their reflection points located on a first plane; the laser amplification system also has multiple planar reflectors, and at least some of the planar reflectors have their reflection points located on a second plane, which is parallel to the first plane.

6. The laser amplification system according to claim 5, characterized in that, The laser amplification system satisfies the following relationships: L1 < L2, L1 + L2 = L; where L1 is the vertical distance from the reflection point of the first reflecting surface to the second plane, L2 is the vertical distance from the first plane to the second plane, and L is the sum of the vertical distances from the reflection point of the first reflecting surface to the second plane and the vertical distances from the first plane to the second plane.

7. The laser amplification system according to claim 4, characterized in that, A single mirror-reflecting module includes a single planar reflector and two planar reflectors. The two planar reflectors correspond to the second reflective surface and the third reflective surface, respectively. The distance between the reflection point of the second reflective surface and the reflection point of the third reflective surface is D1, and the distance between the reflection points of the two planar reflectors is D2. The mirror-reflecting module satisfies the relationship: D2 = D1.

8. The laser amplification system according to claim 7, characterized in that, The laser amplification system includes multiple mirror reflection modules arranged in an array. Each mirror reflection module includes a first mirror reflection module. The minimum distance between the reflection point of the plane mirror of the first mirror reflection module and the reflection point of the plane mirror of the other mirror reflection module is D3. The minimum distance between the reflection point of the plane mirror of the first mirror reflection module and the reflection point of the plane mirror of the other mirror reflection module is D4. The mirror reflection modules satisfy the following relationship: D1 = D2 = D3 = D4.

9. The laser amplification system according to claim 7, characterized in that, The laser amplification system includes multiple mirror reflection modules arranged in a ring; at least some of the reflective points of the planar mirrors are located on a first circumference, and at least some of the reflective points of the planar mirrors are located on a second circumference, the radius of the first circumference is R1, and the radius of the second circumference is R2; the mirror reflection modules satisfy the relationship: R1 = R2.

10. The laser amplification system according to claim 9, characterized in that, At least a portion of the reflective points of the planar mirrors are located on the third circumference, and at least a portion of the reflective points of the planar mirrors are located on the fourth circumference. The center of the third circumference coincides with the center of the first circumference, and the center of the fourth circumference coincides with the center of the second circumference. The radius of the third circumference is R3, and the radius of the fourth circumference is R4. The mirror-reflecting module satisfies the relationship: R3 = R4.

11. The laser amplification system according to claim 7, characterized in that, Along the straight line where the reflection points of the two plane mirrors lie, the length of a single plane mirror is D0, and the plane mirrors satisfy the following relationship: D0 <D2。 12. The laser amplification system according to claim 1, characterized in that, The laser amplifier further includes a polarizing beam splitter, a retroreflector, and a polarization converter. The polarizing beam splitter, the retroreflector, and the polarization converter are located on the reflection side of the gain module. The polarization converter is located between the gain module and the retroreflector. The polarization converter is used to change the polarization state of the laser. The polarizing beam splitter is located at the incident end of the laser amplification system. The retroreflector is used to vertically reflect the laser transmitted by the gain module. The polarization converter is located between the retroreflector and the gain module.

13. The laser amplification system according to claim 1, characterized in that, The laser amplification system also includes a displacement mechanism connected to the planar reflector, which is used to move the planar reflector in the vertical direction from the gain module to the planar reflector.

14. A laser amplifier, characterized in that, The system includes a pump source, a seed source, and the laser amplification system according to any one of claims 1-13, wherein the pump source is used to provide pump energy to the gain medium of the laser amplification system, and the seed source is located on the reflection side of the gain module of the laser amplification system and is used to emit incident laser light to the gain module.

15. The laser amplifier according to claim 14, characterized in that, The laser amplifier also includes a control board, which is electrically connected to both the pump source and the seed source. The control board is used to control the pump source to provide pump energy to the gain medium, and the control board is also used to control the seed source to emit incident laser light to the gain module.

16. A laser processing device, characterized in that, The laser amplifier includes a beam splitter and the laser amplifier as described in claim 14 or 15 above. The gain module of the laser amplifier is used to reflect the incident laser into an outgoing laser. The beam splitter is located on the reflection side of the gain module and is used to receive and split the outgoing laser.

17. The laser processing equipment according to claim 16, characterized in that, The laser processing equipment also includes a focusing lens, which is located on the beam splitter side of the beam splitter. The beam splitter is used to split the emitted laser into a first laser beam and a second laser beam. The focusing lens is used to receive the first laser beam and focus it onto the workpiece.

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