A pulsed laser

Abstract

The application provides a kind of pulse laser, belongs to solid laser technical field.The resonant cavity of the pulse laser includes concave-convex mirror, gain medium, Q-switch module, target shaping lens group and aspheric mirror arranged in turn along the direction of optical axis.Concave-convex mirror and aspheric mirror constitute laser resonant cavity;Target shaping lens group is used to exert spherical aberration to the light beams of different transverse modes generated in resonant cavity, so that the actual focal points of different transverse mode light beams are separated along the direction of optical axis;Aspheric mirror is connected with displacement adjusting device, which is used to adjust the position of aspheric mirror along the direction of optical axis, so that the reflecting surface of aspheric mirror is aligned with the actual focal points of different transverse modes, and the switching output of different transverse mode lasers is realized.The application scheme can output high-energy, pure high-order transverse mode laser, and has the advantages of simple structure, easy debugging and high system stability.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, and specifically relates to a pulsed laser. Background Technology

[0002] The transverse mode of a solid-state laser output is a physical quantity describing the intensity distribution and phase structure within the cross-section of its beam. Common transverse modes include the fundamental mode (TEM). 00 ) and higher-order transverse modes (such as TEM) 01 TEM 10 (etc.). The basic mode has the best beam quality, but its energy extraction efficiency is relatively low; while the higher-order transverse mode has a larger mode volume and can extract more energy from the gain medium, thereby obtaining higher pulse energy output.

[0003] In applications requiring high-energy pulses, utilizing higher-order transverse modes alone offers unique advantages. For example, in fields such as laser shock peening, laser ranging, and lidar, higher-order transverse modes can provide a larger beam area or specific spatial distribution while maintaining high single-pulse energy, thereby meeting specific application requirements.

[0004] Therefore, how to effectively obtain high-energy, pure high-order transverse mode lasers has become one of the important directions in solid-state laser research. Summary of the Invention

[0005] This application provides a pulsed laser that can output high-energy, pure, high-order transverse-mode laser.

[0006] This invention is achieved through the following technical solution: This application provides a pulsed laser, the resonant cavity of which includes: a concave and convex mirror, a gain medium, a Q-switching module, a target shaping lens group, and an aspherical mirror arranged sequentially along the optical axis of the resonant cavity; The concave and convex mirrors and the aspherical mirror are used to form the laser resonant cavity; the concave and convex mirrors serve as the output mirrors of the resonant cavity; and the aspherical mirrors serve as the reflecting mirrors of the resonant cavity. The target shaping lens group is used to apply spherical aberration to the beams of different transverse modes generated in the resonant cavity, so that the actual focal points of the beams of different transverse modes in the resonant cavity are separated along the optical axis direction. The aspherical mirror is connected to a displacement adjustment device; The displacement adjustment device is used to adjust the position of the aspherical reflector along the optical axis so that the reflecting surface of the aspherical reflector is aligned with the actual focal point of different transverse modes, thereby realizing the switching output of different transverse mode lasers.

[0007] In one alternative implementation, the resonant cavity further includes a cornerstone prism; the cornerstone prism is located between the gain medium and the Q-switching module; The cornerstone prism is used to bend the optical path within the laser resonant cavity, thereby compressing the spatial dimensions of the laser along the optical axis.

[0008] In one alternative implementation, the target shaping lens group includes a first shaping lens and a second shaping lens; the second shaping lens is located between the aspherical mirror and the first shaping lens; The first shaping lens is used to pre-shape the beam in the laser resonant cavity to obtain a collimated beam containing different transverse modes; The second shaping lens is used to apply spherical aberration to the collimated beam containing different transverse modes, so that the actual focal points of the beams of different transverse modes in the resonant cavity are separated along the optical axis.

[0009] In one alternative implementation, the Q-switching module includes: a polarizing beam splitter, a quarter-wave plate, and a Q-switching crystal; the polarizing beam splitter is located between the cornerstone prism and the quarter-wave plate; and the Q-switching crystal is located between the quarter-wave plate and the target shaping lens.

[0010] In one optional implementation, the radius of curvature R of the concave-convex mirror is ±1m; the gain medium is an Nd:YAG crystal with dimensions of φ8×60mm; the polarizing beam splitter has dimensions of 12×12×12mm; the Q-switching crystal is an RTP crystal; the first shaping lens is a plano-convex lens with a focal length F=100mm; the second shaping lens is a plano-convex lens with a focal length F=15mm; and the aspherical reflector is an ellipsoidal reflector with a vertex radius of curvature R=15mm and a conic constant k=-0.7.

[0011] Compared with the prior art, the beneficial effects of this invention are as follows: This application introduces spherical aberration through a target shaping lens group, causing the actual focal points of beams of different transverse modes to be separated along the optical axis within the resonant cavity. Combined with a displacement adjustment device, the aspherical mirror is moved along the optical axis so that its reflecting surface is aligned with the actual focal points of different transverse modes, thereby achieving the switching output of different transverse mode lasers. At the same time, this application utilizes the low diffraction loss characteristics of the aspherical mirror to achieve high-energy pulse output and can output pure high-order transverse mode lasers independently. It has the advantages of simple structure, easy debugging, and high system stability. Attached Figure Description

[0012] Figure 1 A schematic diagram illustrating mode selection within the resonant cavity of a laser, provided as an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a folded resonant cavity for a laser, provided in an embodiment of this application.

[0013] The figure is labeled as follows: 1-Concave-convex mirror, 2-Pump source, 3-Cornered pyramidal prism, 4-Polarizing beam splitter, 5-Quarter-wave plate, 6-Q-switched crystal, 7-First shaping lens, 8-Second shaping lens, 9-Aspherical mirror, 10-Displacement adjustment device, 11-Gain medium. Detailed Implementation

[0014] In existing solutions, high-order transverse mode laser output is typically achieved using methods such as pinhole aperture mode selection or cavity design. Pinhole aperture mode selection uses a small aperture placed inside the cavity to achieve fundamental mode oscillation and filter out higher-order modes; cavity design uses parameters such as specific concave and convex cavities to design and cause fundamental mode oscillation, thus filtering out higher-order modes.

[0015] However, both approaches have significant drawbacks. The pinhole aperture mode selection can only output the fundamental mode or the fundamental mode plus higher-order modes, and cannot output higher-order modes independently. Furthermore, pinhole filtering is prone to contamination. Similarly, the cavity design can only output the fundamental mode or the fundamental mode plus higher-order modes, and cannot output higher-order mode lasers independently. Moreover, the design is complex, debugging is difficult, and the requirements for processing accuracy and assembly are extremely high. It is also difficult to balance the energy balance and separation accuracy between different transverse modes.

[0016] Based on this, this application provides a pulsed laser, belonging to the field of solid-state laser technology. The resonant cavity of this pulsed laser includes a concave-convex mirror 1, a gain medium 11, a Q-switching module, a target shaping lens group, and an aspherical reflector 9 arranged sequentially along the optical axis. The concave-convex mirror 1 and the aspherical reflector 9 constitute the laser resonant cavity; the target shaping lens group is used to apply spherical aberration to the beams of different transverse modes generated within the resonant cavity, causing the actual focal points of the different transverse mode beams to separate along the optical axis; the aspherical reflector 9 is connected to a displacement adjustment device, which is used to adjust the position of the aspherical reflector 9 along the optical axis, so that the reflecting surface of the aspherical reflector 9 is aligned with the actual focal points of different transverse modes, thereby achieving switching output of different transverse mode lasers.

[0017] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] The pulsed laser provided in this application is essentially a pulsed Q-switched solid-state laser. The goal of designing this laser is to output high-energy, pure, high-order transverse mode laser pulses, thereby providing a high-quality light source for fields such as laser processing, nonlinear frequency conversion, and lidar.

[0019] The resonant cavity of the pulsed laser of this application includes: a concave-convex mirror 1, a gain medium 11, a Q-switching module, a target shaping lens group, and an aspherical reflector 9, arranged sequentially along the optical axis of the resonant cavity.

[0020] This application adopts a side-pumping method, in which the pump source 2 is disposed on the side of the gain medium 11 to provide a uniform and efficient pump light distribution, thereby improving the thermal management capability of the gain medium 11 and ensuring the stability of high-energy pulse output.

[0021] Specifically, the concave-convex mirror 1 and the aspherical mirror 9 in this application together constitute the resonant cavity of the laser; wherein, the concave-convex mirror 1 serves as the output mirror of the resonant cavity, and the aspherical mirror 9 serves as the reflector of the resonant cavity.

[0022] The target shaping lens group is used to apply spherical aberration to beams of different transverse modes generated in the resonant cavity, so that the actual focal points of beams of different transverse modes in the resonant cavity are separated along the optical axis.

[0023] The aspherical mirror 9 is connected to a displacement adjustment device; the displacement adjustment device is used to adjust the position of the aspherical mirror 9 along the optical axis so that the reflecting surface of the aspherical mirror 9 is aligned with the actual focal point of different transverse modes, so as to realize the switching output of different transverse mode lasers.

[0024] Figure 1 This is a schematic diagram illustrating mode selection within the resonant cavity of a laser, provided as an embodiment of this application. (Combined with...) Figure 1 As shown, the fundamental mode beam and higher-order mode beam generated within the laser resonant cavity, after being subjected to spherical aberration by the target shaping lens group, have their actual focal points separated along the optical axis. Specifically, the fundamental mode beam, less affected by spherical aberration, has its focal point located at the first focal point on the optical axis; while the higher-order mode beam, due to more significant spherical aberration, has its focal point shifted to the second focal point on the optical axis, with an axial distance between it and the fundamental mode focal point. By adjusting the position of the aspherical mirror 9 along the optical axis, the aspherical mirror 9 can be selectively aligned with the actual focal point of the fundamental mode or the higher-order mode, thus achieving pure switching output of different transverse mode lasers.

[0025] It should be noted that the aspherical reflector 9 in the resonant cavity of this application can enhance the selectivity for different oscillation modes, expand the effective reflection area, and reduce the peak power density on the mirror surface, thus creating favorable conditions for achieving high peak power pulse output.

[0026] It is understandable that if the concave-convex mirror 1, gain medium 11, Q-switching module, target shaping lens group, and aspherical reflector 9 are arranged in a straight line along the optical axis of the resonant cavity, the length of the resonant cavity would be excessive. To compress the spatial dimensions of the laser along the optical axis and achieve a compact design, the resonant cavity of the laser in this application also includes a cornerstone prism 3; this cornerstone prism 3 is located between the gain medium 11 and the Q-switching module; this cornerstone prism 3 is used to bend the optical path within the laser resonant cavity, thereby compressing the spatial dimensions of the laser along the optical axis.

[0027] It should be noted that the corner cube prism 3 is chosen as the optical path reversal element in this application, rather than a plane mirror, because the corner cube prism 3 has the characteristics of being insensitive to the incident angle and having the outgoing light strictly parallel to the incident light. This can effectively reduce the difficulty of assembly and debugging while compressing the optical path and ensure the stability of the resonant cavity.

[0028] Figure 2 This is a schematic diagram of a folded resonant cavity for a laser, provided as an embodiment of this application. (Combined with...) Figure 2 As shown, the resonant cavity of the laser includes: a concave-convex mirror 1, a pump source 2, a cornerstone prism 3, a polarizing beam splitter 4, a quarter-wave plate 5, a Q-switched crystal 6, a first shaping lens 7, a second shaping lens 8, an aspherical mirror 9, a high-precision electric displacement device 10, and a gain medium 11.

[0029] Among them, the concave and convex mirror 1 and the aspherical mirror 9 constitute the two ends of the resonant cavity and are used to generate laser oscillation.

[0030] Under the excitation of pump source 2, gain medium 11 achieves population inversion and provides laser gain, providing energy for laser oscillation in resonant cavity.

[0031] The corner cube prism 3 is used to achieve optical path folding in the resonant cavity, thereby optimizing the space of the laser and making it more compact.

[0032] The polarization beam splitter 4, the quarter-wave plate 5, and the Q-switched crystal 6 together constitute the Q-switching module in this application. They work together to achieve Q-switched output of laser pulses and generate high-energy, narrow-pulse-width pulsed lasers by controlling the loss period of the resonant cavity.

[0033] The first shaping lens 7 and the second shaping lens 8 together constitute the target shaping lens group in this application; the first shaping lens 7 is used to pre-shape the beam in the laser resonant cavity to obtain a collimated beam containing different transverse modes; the second shaping lens 8 is a short focal length shaping lens, used to apply spherical aberration to the collimated beam containing different transverse modes, so that the actual focal points of the beams of different transverse modes in the resonant cavity are separated along the optical axis direction.

[0034] The aspherical mirror 9 is positioned along the optical axis so that its reflecting surface is aligned with the actual focal point of different transverse modes, thereby enabling the switching output of different transverse mode lasers.

[0035] An aspherical reflector 9 is connected to a displacement adjustment device 10. The displacement adjustment device 10 changes the cavity length of the resonant cavity by finely adjusting the position of the aspherical reflector 9, thereby enabling the selection of different transverse mode oscillation modes within the cavity. This displacement adjustment device adopts a high-precision electric control design, which allows the output laser mode to be continuously changed without manual adjustment, thus achieving switching between different transverse modes; thereby realizing high-pulse-energy, pure, high-order transverse mode laser.

[0036] For example, Figure 2 The specific parameters of each component in the resonant cavity of the laser shown are as follows: the concave-convex mirror 1 is a concave-convex mirror with a radius of curvature R=±1m; the gain medium 11 is an Nd:YAG crystal with a size of φ8×60mm; the polarization beam splitter 4 has a size of 12×12×12mm; the Q-switching crystal 6 is an RTP crystal; the first shaping lens 7 is a plano-convex lens with a focal length F=100mm; the second shaping lens 8 is a plano-convex lens with a focal length F=15mm; and the aspherical reflector 9 is an ellipsoidal reflector with a vertex radius of curvature R=15mm and a conic constant k=-0.7.

[0037] Figure 2 The specific debugging process for the laser in the image is as follows: Step 1: According to the laser design requirements, select and build the concave-convex mirror 1, gain medium 11, cornerstone prism 3, polarizing beam splitter 4, and aspherical reflector 9 in sequence to construct the basic laser resonant cavity. Then, place the first shaping lens 7 and the second shaping lens 8 into the optical path at the designed distance to ensure that the entire resonant cavity and the shaping optical path are basically coaxial.

[0038] Step 2: Under low pump power, first coarsely adjust the distance between the first shaping lens 7 and the second shaping lens 8 to make the resonant cavity generate stable static laser oscillation, ensuring that the basic optical path has the conditions for oscillation.

[0039] Step 3: Gradually increase the pump power to near the target mode, and use the high-precision displacement adjustment device 10 to finely adjust the position of the aspherical mirror 9 to make the laser oscillate optimally in order to obtain the optimal continuous wave output mode.

[0040] Step 4: Insert a quarter-wave plate 5 and a Q-switched crystal 6 into the pre-tuned resonant cavity to complete the optical path configuration and realize the pulsed Q-switched output of the laser.

[0041] Step 5: When the laser is outputting pulsed light normally, the displacement adjustment device 10 continues to finely adjust the front and rear positions of the aspherical mirror 9. By utilizing the difference in reflection gain of the aspherical mirror 9 at different positions, the dynamic selection and optimization of the intracavity laser mode can be achieved, and finally, a high-energy, pure high-order transverse mode laser pulse is output.

[0042] The present invention has been described in detail above through embodiments, but the content described is only an exemplary embodiment of the present invention and should not be considered as limiting the scope of the present invention. The scope of protection of the present invention is defined by the claims. Any technical solutions designed by those skilled in the art using the technical solutions described in the present invention, or similar technical solutions designed by those skilled in the art under the inspiration of the technical solutions of the present invention, within the substance and scope of protection of the present invention, to achieve the above-mentioned technical effects, or equivalent changes and improvements made to the scope of the application, should still fall within the patent protection scope of the present invention. It should be noted that, for clarity, descriptions of some components and processes that are not directly and obviously related to the scope of protection of the present invention but are known to those skilled in the art have been omitted in the description of the present invention.

Claims

1. A pulsed laser, characterized in that, The resonant cavity of the laser includes: a concave and convex mirror, a gain medium, a Q-switching module, a target shaping lens group, and an aspherical reflector arranged sequentially along the optical axis of the resonant cavity; The concave and convex mirrors and the aspherical mirror are used to form the laser resonant cavity; the concave and convex mirrors serve as the output mirrors of the resonant cavity; and the aspherical mirrors serve as the reflecting mirrors of the resonant cavity. The target shaping lens group is used to apply spherical aberration to the beams of different transverse modes generated in the resonant cavity, so that the actual focal points of the beams of different transverse modes in the resonant cavity are separated along the optical axis direction. The aspherical mirror is connected to a displacement adjustment device; The displacement adjustment device is used to adjust the position of the aspherical reflector along the optical axis so that the reflecting surface of the aspherical reflector is aligned with the actual focal point of different transverse modes, thereby realizing the switching output of different transverse mode lasers.

2. The laser according to claim 1, characterized in that, The resonant cavity further includes a cornerstone prism; the cornerstone prism is located between the gain medium and the Q-switching module; The cornerstone prism is used to bend the optical path within the laser resonant cavity, thereby compressing the spatial dimensions of the laser along the optical axis.

3. The laser according to claim 2, characterized in that, The target shaping lens group includes a first shaping lens and a second shaping lens; the second shaping lens is located between the aspherical mirror and the first shaping lens; The first shaping lens is used to pre-shape the beam in the laser resonant cavity to obtain a collimated beam containing different transverse modes; The second shaping lens is used to apply spherical aberration to the collimated beam containing different transverse modes, so that the actual focal points of the beams of different transverse modes in the resonant cavity are separated along the optical axis.

4. The laser according to claim 3, characterized in that, The Q-switching module includes: a polarizing beam splitter, a quarter-wave plate, and a Q-switching crystal; the polarizing beam splitter is located between the cornerstone prism and the quarter-wave plate; the Q-switching crystal is located between the quarter-wave plate and the target shaping lens.

5. The laser according to claim 4, characterized in that, The radius of curvature of the concave-convex mirror is R=±1m; the gain medium is an Nd:YAG crystal with a size of φ8×60mm; the size of the polarizing beam splitter is 12×12×12mm; the Q-switching crystal is an RTP crystal; the first shaping lens is a plano-convex lens with a focal length of F=100mm; the second shaping lens is a plano-convex lens with a focal length of F=15mm; the aspherical reflector is an ellipsoidal reflector with a vertex radius of curvature R=15mm and a conic constant k=-0.7.

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