Laser system

Abstract

The invention discloses a laser system, which relates to the laser technology and comprises a laser used for emitting laser to a laser spectroscope M1; the laser spectroscope M1 is used for dividing the laser emitted by the laser into first pumping laser and second pumping laser; the OPO is used for carrying out nonlinear frequency conversion on the first pumping laser; the OPO secondary pumping system is used for carrying out secondary pumping based on the first residual pumping light; the OPA is used for performing OPA optical parametric amplification on the seed laser and the second pumping laser; and the OPA secondary pumping system is used for outputting the second residual pumping light to the beam combiner M10 and reflecting the second residual pumping light to the OPA so as to realize secondary pumping and increase the power of the amplified laser. According to the laser system, the light beam quality of the pump light and the utilization rate of the pump light are effectively improved, the packaging structures of the OPO and the OPA are optimized, and the light beam output efficiency and the light beam quality of medium-long wave laser are improved.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a laser system. Background Art

[0002] Most of the technologies for achieving high-power medium and long-wave output at home and abroad use 2μm solid-state laser pumping optical parametric oscillators (OPOs). With the increasing demand for medium-wave laser power, higher requirements are placed on optical parametric oscillators (OPOs). At the same time, with the increase in the power of the pump light source, the thermal effect of the OPO will become very serious, resulting in serious distortion of the transmitted pump light, thereby affecting the conversion efficiency of the OPO. The existing technology achieves 3-5μm / 8-12μm output through the OPO cavity, and there are bottleneck problems such as low pump light utilization, low output efficiency, large optical path volume, and poor output beam quality.

[0003] The existing technology uses a fully solid-state 2-micron laser to pump a nonlinear optical parametric oscillator (OPO) to generate 3-5μm / 8-12μm infrared laser, which has problems such as low output efficiency, large optical path volume, and poor output beam quality. Summary of the invention

[0004] The embodiment of the present application provides a laser system, which improves the beam quality of the output laser and solves the problems of low output efficiency, large optical path volume, poor output beam quality, etc. existing in the prior art.

[0005] The present application provides a laser system, comprising:

[0006] A laser, used to emit laser light to the laser beam splitter M1, serving as a pump source for the optical parametric oscillator OPO and the optical parametric amplifier OPA;

[0007] A laser beam splitter M1 is used to split the laser emitted by the laser into a first pump laser and a second pump laser, wherein the first pump laser is incident on the first total reflection mirror M3 to pump the OPO to generate a seed laser, and the second pump laser is incident on the beam combiner M10 to pump the OPA to amplify the seed laser generated by the OPO;

[0008] The OPO is used to perform nonlinear frequency conversion on the first pump laser, and output the seed laser and the first residual pump light to the first beam splitter M9, the seed laser is transmitted through the first beam splitter M9 and incident on the beam combiner M10, and the first residual pump light is reflected by the first beam splitter M9 to the OPO secondary pumping system;

[0009] The OPO secondary pumping system is used to output the first remaining pump light reflected by the first beam splitter M9 to the first total reflection mirror M3, and the first total reflection mirror M3 reflects the first remaining pump light to the OPO to perform secondary pumping to increase the power of the seed laser;

[0010] The OPA is used to perform OPA optical parametric amplification on the seed laser and the second pump laser, and output the amplified laser and the second residual pump light to the second beam splitter M12, the amplified laser is output through the second beam splitter M12, and the second residual pump light is reflected by the second beam splitter M12 to the OPA secondary pumping system;

[0011] The OPA secondary pumping system is used to output the second remaining pumping light reflected by the second beam splitter M12 to the beam combiner M10, so as to reflect the second remaining pumping light to the OPA at the beam combiner M10 to perform secondary pumping to increase the power of the amplified laser.

[0012] Optionally, the OPO secondary pumping system includes: a first shaping mirror, a second total reflection mirror M4, and a third total reflection mirror M2, wherein:

[0013] The first remaining pump light reflected by the first beam splitter M9 is incident on the first shaping mirror, and is reflected by the second total reflection mirror M4 and the third total reflection mirror M2 before being incident on the first total reflection mirror M3, so that the first remaining pump light is reflected by the first total reflection mirror M3 to the OPO for secondary pumping.

[0014] Optionally, an aspherical surface is provided on the first shaping mirror to correct the wavefront distortion of the first residual pump light.

[0015] Optionally, the OPO includes a resonant cavity mirror M5, a resonant cavity mirror M6, a resonant cavity mirror M7 and a resonant cavity mirror M8, wherein a nonlinear crystal zinc germanium phosphorus ZGP crystal is arranged between the resonant cavity mirror M7 and the resonant cavity mirror M8.

[0016] Optional, corresponding to the medium wave band,

[0017] The resonant cavity mirror M5 and the resonant cavity mirror M6 are coated with a 3-5 μm HR film;

[0018] The resonant cavity mirror M7 is coated with 2μm HT and 3-5μm HR films;

[0019] The resonant cavity mirror M8 is coated with 2 μm HT, T 3-5μm =50% film.

[0020] Optionally, the OPA secondary pumping system includes: a second shaping mirror, a fourth total reflection mirror M11, and a fifth total reflection mirror M13, wherein:

[0021] The second remaining pump light reflected by the second beam splitter M12 is incident on the second shaping mirror, and is reflected by the fourth total reflection mirror M11 and the fifth total reflection mirror M13 before being incident on the beam combining mirror M10, so that the second remaining pump light is reflected by the beam combining mirror M10 to the OPA for secondary pumping.

[0022] Optionally, the second shaping mirror is provided with an aspherical surface for correcting the wavefront distortion of the second residual pump light.

[0023] Optionally, a first laser lens f1 is further provided between the laser beam splitter M1 and the first total reflection mirror M3.

[0024] Optionally, a second laser lens f4 is arranged between the first beam splitter M9 and the beam combiner M10.

[0025] Optionally, the OPO includes a first ZGP crystal, and the OPA includes a second ZGP crystal, the first ZGP crystal and the second ZGP crystal both include a ZGP crystal slat and two copper heat sinks, the two copper heat sinks are respectively located on both sides of the ZGP crystal slat, and indium based on electromagnetic heating is used as a welding medium between the ZGP crystal and the copper heat sink.

[0026] The embodiments of the present application effectively improve the beam quality and the output efficiency of the laser beam, thereby solving the problems of low output efficiency, large optical path volume, and poor output beam quality existing in the prior art.

[0027] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0029] Figure 1 A schematic diagram of the optical architecture of the medium- and long-wave laser system of an embodiment of the present application;

[0030] Figure 2This is a schematic diagram of the deformable mirror structure and effect of the medium- and long-wave laser system of the embodiment of the present application;

[0031] Figure 3 This is a schematic diagram of the packaging of the nonlinear crystal ZGP of the medium- and long-wave laser system of the embodiment of the present application;

[0032] Figure 4 This is an application example of the long-wave optical path of the medium- and long-wave laser system in the embodiment of the present application. DETAILED DESCRIPTION

[0033] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0034] The traditional solution uses OPO to achieve 100W medium wave output, which is extremely large in size, has poor output beam quality, and has a great risk of damage. The present application embodiment provides a laser system, such as Figure 1 As shown, including:

[0035] The laser is used to emit laser light to the laser spectrometer M1 as a pump source for the optical parametric oscillator OPO and the optical parametric amplifier OPA. In some specific examples, the laser can be a 2μm pulse laser, for example, 1200W, with a pulse width of 50ns and a repetition frequency of 10-15Khz. The subsequent embodiments of this application are illustrated by taking the output of the first wavelength laser of 3-5μm and the second wavelength laser of 2μm as an example. The laser system of this application is also applicable to output schemes of other bands, which are not listed here one by one.

[0036] The laser beam splitter M1 is used to split the laser emitted by the laser into a first pump laser and a second pump laser, wherein the first pump laser is incident on the first total reflection mirror M3 to pump the OPO to generate a seed laser, and the second pump laser is incident on the beam combiner M10 to pump the OPA to amplify the seed laser generated by the OPO. In some examples, the first wavelength of laser light required to be output by the system of the present application is, for example, 3-5μm. Based on this example, the laser beam splitter M1 can use a 2μm laser beam splitter with a 2μm beam splitting film layer on the surface, and the beam splitting ratio is 10%-100%. The 2μm laser outputs a high-power 2μm pulsed laser divided into two beams, namely the first pump laser and the second pump laser. The first pump laser is used to pump the OPO to generate a medium-wave seed laser, and the second pump laser is incident on the beam combiner M10 to pump the OPA to amplify the seed laser generated by the OPO.

[0037] like Figure 1As shown, the OPO is used to perform nonlinear frequency conversion on the first pump laser, and output the seed laser and the first residual pump light to the first beam splitter M9. The seed laser is transmitted through the first beam splitter M9 and is incident on the beam combiner M10. The first residual pump light is reflected by the first beam splitter M9 to the OPO secondary pumping system.

[0038] The OPO secondary pumping system is used to output the first remaining pump light reflected by the first beam splitter M9 to the first total reflection mirror M3, and the first total reflection mirror M3 reflects the first remaining pump light to the OPO to perform secondary pumping to increase the power of the seed laser.

[0039] like Figure 1 As shown, the OPA is used to perform OPA optical parametric amplification on the seed laser and the second pump laser, and output the amplified laser and the second residual pump light to the second beam splitter M12. The amplified laser is output through the second beam splitter M12, and the second residual pump light is reflected by the second beam splitter M12 to the OPA secondary pumping system.

[0040] The OPA secondary pumping system is used to output the second remaining pump light reflected by the second beam splitter M12 to the beam combiner M10, so as to reflect the second remaining pump light to the OPA at the beam combiner M10 for secondary pumping to increase the power of the amplified laser.

[0041] The embodiments of the present application effectively improve the beam quality and the output efficiency of the medium- and long-wave laser beams, thereby solving the problems of low output efficiency, large optical path volume, and poor output beam quality in the prior art.

[0042] In some embodiments, the OPO secondary pumping system includes: a first shaping mirror, a second total reflection mirror M4, and a third total reflection mirror M2, wherein:

[0043] The first residual pump light reflected by the first beam splitter M9 is incident on the first shaping mirror, and is reflected by the second total reflection mirror M4 and the third total reflection mirror M2 before being incident on the first total reflection mirror M3, so that the first residual pump light is reflected to the OPO at the first total reflection mirror M3 for secondary pumping. In some embodiments, an aspherical surface is provided on the first shaping mirror to correct the wavefront distortion of the first residual pump light.

[0044] In some embodiments, the OPO includes a resonant cavity mirror M5, a resonant cavity mirror M6, a resonant cavity mirror M7 and a resonant cavity mirror M8, wherein a nonlinear crystal zinc germanium phosphorus ZGP crystal is disposed between the resonant cavity mirror M7 and the resonant cavity mirror M8. Figure 1As shown, for medium and long wave laser systems, in some specific examples, OPO: the first 2μm first pump laser passes through the f1 lens, then through the M3 total reflection mirror, and enters the OPO resonant cavity from the resonant cavity mirror M7. The OPO resonant cavity is composed of resonant cavity mirrors M5, M6, M7 and M8, with nonlinear crystal zinc germanium phosphorus (ZGP) in the middle. Lenses f1-f5 are laser lenses, corresponding to the medium and long wave laser system lenses f1, f2, f3, and f5 are 2μm laser lenses, and lens f4 is a 3-5μm laser lens. The laser system solutions of other wavelengths can adjust the lenses according to actual needs, which are not listed here one by one.

[0045] The laser beam splitter M1 corresponding to the medium and long wave laser system is a 2μm beam splitter coated with a 2μm beam splitting film layer, and the beam splitting ratio is 10%-100%; the third total reflection mirror M2, the first total reflection mirror M3, the second total reflection mirror M4, and the subsequent fourth total reflection mirror M11, the fifth total reflection mirror M13, and the sixth total reflection mirror M14 are 2μm total reflection mirrors, R1.9-2.1μm ≥ 99.9%.

[0046] Still taking the medium and long waves as an example, after the 2μm first pump laser passes through the OPO resonant cavity, it undergoes nonlinear frequency conversion and outputs a 3-5μm seed laser from the resonant cavity mirror M8. The general conversion efficiency is 50-70%, and the efficiency cannot reach 100%. Then there is a converted 2μm first residual pump light at the resonant cavity mirror M8, but this part of the 2μm laser will be in the process of being converted into medium waves (that is, in the process of passing through the ZGP), due to the thermal lens effect and nonlinear effect of the ZGP crystal, causing the quality of the remaining 2μm laser beam to deteriorate, and it is impossible to achieve efficient utilization again. In the embodiment of the present application, this part of the 2μm laser is filtered out at the first beam splitter M9, and the converted medium-wave laser passes through the first beam splitter M9 into the next link, and will serve as the seed laser for the next link.

[0047] The filtered 2μm laser is reflected upward as the first residual pump light at the first beam splitter M9, realizing efficient use of the remaining 2μm laser, and the 2μm laser reflected upward comes to the first shaping mirror. After the degraded 2μm beam passes through the first shaping mirror, the beam quality is improved, and then it is reflected to the total reflection mirror M4, and then through the total reflection mirror M4 to the lens f2 for secondary focusing, and then reflected by the reflection mirror M2. By adjusting the angle, the first residual pump light and the 2μm reflected light of the first pump laser overlap, realizing secondary pumping OPO, thereby greatly improving the overall conversion efficiency of the 2μm pump light.

[0048] The embodiment of the present application designs a four-mirror ring cavity OPO to generate a high beam quality medium-wave seed laser output, which can obtain a 69.8W medium-wave seed light output. Figure 2As shown, the shaping mirror of the embodiment of the present application adopts the structure of xx. The embodiment of the present application improves the OPO efficiency by nearly 20% through the secondary utilization of the first residual pump light by the shaping mirror, and fully utilizes the 2μm residual light.

[0049] In some embodiments, corresponding to the mid-wave band, the resonant cavity mirrors M5 and M6 are coated with 3-5 μm HR film; the resonant cavity mirror M7 is coated with 2 μm HT and 3-5 μm HR film; the resonant cavity mirror M8 is coated with 2 μm HT and 3-5 μm HR film. 3-5μm =50% film.

[0050] In some embodiments, the OPA secondary pumping system includes: a second shaping mirror, a fourth total reflection mirror M11, and a fifth total reflection mirror M13, wherein the second remaining pump light reflected by the second beam splitter M12 is incident on the second shaping mirror, and after being reflected by the fourth total reflection mirror M11 and the fifth total reflection mirror M13, is incident on the beam combining mirror M10, so that the second remaining pump light is reflected to the OPA at the beam combining mirror M10 for secondary pumping.

[0051] like Figure 1 As shown, in a specific example, a fifth laser lens f5 is disposed between the fourth total reflection mirror M11 and the fifth total reflection mirror M13. In some embodiments, the laser beam splitter M1 splits the second pump laser emitted by the laser, and the second pump laser is incident on the beam combiner M10 through the sixth total reflection mirror M14 to reuse the laser of the second wavelength for a second time, wherein a third laser lens f3 is disposed between the laser beam splitter M1 and the sixth total reflection mirror M14. In some embodiments, a first laser lens f1 is also disposed between the laser beam splitter M1 and the first total reflection mirror M3.

[0052] In a specific example, the OPA process sacrifices the 2μm laser and amplifies the 3-5μm laser. During the amplification process, the power of the 2μm laser will decrease, while the power of the 3-5μm laser will increase. At the same time, there are efficiency issues in the conversion process. As in the OPO process, there will be thermal effects and other conditions that cause the quality of the remaining 2μm laser beam to deteriorate. In the embodiment of the present application, a second beam splitter M12 is used to filter out the 2μm laser, and the 3-5μm laser is output through the second beam splitter M12. The OPA secondary pumping system is used to output the 2μm second residual pumping light reflected by the second beam splitter M12 to the beam combiner M10, thereby adjusting the remaining 2μm second residual pumping light to coincide with the original optical path, thereby achieving efficient secondary utilization of the 2μm laser.

[0053] In some embodiments, the second shaping mirror is provided with an aspherical surface for correcting the wavefront distortion of the second residual pump light.

[0054] The thermal effect of ZGP is caused by the absorption of laser by crystal, which is inevitable. The crystal needs to be cooled, which involves the packaging method of the crystal. The traditional method uses square crystal packaging, and uses extrusion to fill the heat conduction cutoff between the crystal and the heat sink, and clamps the crystal with screws for conduction heat dissipation. Disadvantages: stress will cause laser degradation, and uneven contact will lead to poor heat dissipation.

[0055] In some embodiments of the present application, the OPO includes a first ZGP crystal, and the OPA includes a second ZGP crystal, the first ZGP crystal and the second ZGP crystal each include a ZGP crystal slat, two copper heat sinks, the two copper heat sinks are respectively located on both sides of the ZGP crystal slat, and indium based on electromagnetic heating is used as a welding medium between the ZGP crystal and the copper heat sink. Figure 3 As shown, in the specific implementation, the crystal is cut into a slat structure, and then an instantaneous liquid phase welding technology is used. Electromagnetic heating is used to directly act on the welding surface. The liquid phase time is short, which reduces uneven heat conduction and greatly reduces the welding stress of the module to ensure the efficiency and beam quality of the medium-wave output.

[0056] Based on the aforementioned optical path structure, the present application embodiment proposes an application example of a medium- and long-wave laser system in a long-wave laser. By using ZGPs with different matching angles and different lens designs, long-wave laser output can be achieved under the same optical path structure. Figure 4 As shown, where:

[0057] 2μm laser: 2μm pulse laser, which is the pump source of OPO+OPA;

[0058] f1-f5 are laser lenses, of which f1, f2, f3, f5 are 2μm laser lenses, and f4 is 8-12μm laser lens;

[0059] M1 is a 2μm laser beam splitter, coated with a 2μm beam splitting film layer, with a beam splitting ratio of 10%-100%;

[0060] M2, M3, M4, M11, M13, M14 are 2μm total reflection mirrors, R 1.9-2.1μm ≥99.9%;

[0061] Reshaping mirror 1, reshaping mirror 2, coated with full reflection film R 1.9-2.1μm ≥99.9%, used to correct the wavefront distortion of the 2μm residual light and improve the beam quality of the residual light;

[0062] M5-M8 are OPO resonant cavity mirrors, M7 is coated with 2μmHT, 8-12μmHR, 2.6-2.8μmHR film, M8 is coated with 2μmHT, T 8-12μm=50%, 2.6-2.8μmHR, M5 and M6 are plated with 8-12μmHR and 2.6-2.8μmHR film layers;

[0063] M9 and M12 are beam splitters coated with 2μm HR and 8-12μm HT films;

[0064] M10 is a beam combiner, coated with 8-12μmHT and 2μmHR films.

[0065] The embodiment of the present application adopts an OPO+OPA nonlinear frequency generator and a deformable mirror to shape the remaining pump light of the OPO and OPA for secondary use, and the nonlinear output efficiency is increased by nearly 40%. The solution of the present application can achieve a medium-wave laser output of more than 212.5W, and the overall optical-to-optical conversion efficiency reaches 68%, and the beam quality M 2 =2.89, while the efficiency is improved, the volume is only 1 / 4 of the original, and the beam quality is improved by 40%, creating a multi-level expansion space for mid-infrared lasers.

[0066] It should be noted that in the embodiments of the present application, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0067] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0068] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A laser system, characterized in that: include: A laser, used to emit laser light to the laser beam splitter M1, serving as a pump source for the optical parametric oscillator OPO and the optical parametric amplifier OPA; A laser beam splitter M1 is used to split the laser emitted by the laser into a first pump laser and a second pump laser, wherein the first pump laser is incident on the first total reflection mirror M3 to pump the OPO to generate a seed laser, and the second pump laser is incident on the beam combiner M10 to pump the OPA to amplify the seed laser generated by the OPO; The OPO is used to perform nonlinear frequency conversion on the first pump laser, and output the seed laser and the first residual pump light to the first beam splitter M9, the seed laser is transmitted through the first beam splitter M9 and incident on the beam combiner M10, and the first residual pump light is reflected by the first beam splitter M9 to the OPO secondary pumping system; The OPO secondary pumping system is used to output the first remaining pump light reflected by the first beam splitter M9 to the first total reflection mirror M3, and the first total reflection mirror M3 reflects the first remaining pump light to the OPO to perform secondary pumping to increase the power of the seed laser; The OPA is used to perform OPA optical parametric amplification on the seed laser and the second pump laser, and output the amplified laser and the second residual pump light to the second beam splitter M12, the amplified laser is output through the second beam splitter M12, and the second residual pump light is reflected by the second beam splitter M12 to the OPA secondary pumping system; The OPA secondary pumping system is used to output the second remaining pumping light reflected by the second beam splitter M12 to the beam combiner M10, so as to reflect the second remaining pumping light to the OPA at the beam combiner M10 to perform secondary pumping to increase the power of the amplified laser.

2. The laser system according to claim 1, characterized in that The OPO secondary pumping system includes: a first shaping mirror, a second total reflection mirror M4, and a third total reflection mirror M2, wherein: The first remaining pump light reflected by the first beam splitter M9 is incident on the first shaping mirror, and is reflected by the second total reflection mirror M4 and the third total reflection mirror M2 before being incident on the first total reflection mirror M3, so that the first remaining pump light is reflected by the first total reflection mirror M3 to the OPO for secondary pumping.

3. The laser system according to claim 2, characterized in that The first shaping mirror is provided with an aspherical surface for correcting the wavefront distortion of the first residual pump light.

4. The laser system according to claim 1, characterized in that The OPO includes a resonant cavity mirror M5, a resonant cavity mirror M6, a resonant cavity mirror M7 and a resonant cavity mirror M8, wherein a nonlinear crystal zinc germanium phosphorus ZGP crystal is arranged between the resonant cavity mirror M7 and the resonant cavity mirror M8.

5. The laser system according to claim 4, characterized in that Corresponding to the medium wave band, The resonant cavity mirror M5 and the resonant cavity mirror M6 are coated with a 3-5 μm HR film; The resonant cavity mirror M7 is coated with 2μm HT and 3-5μm HR films; The resonant cavity mirror M8 is coated with 2 μm HT, T 3-5μm =50% film.

6. The laser system according to claim 1, characterized in that The OPA secondary pumping system includes: a second shaping mirror, a fourth total reflection mirror M11, and a fifth total reflection mirror M13, wherein the second remaining pumping light reflected by the second beam splitter M12 is incident on the second shaping mirror, and is reflected by the fourth total reflection mirror M11 and the fifth total reflection mirror M13 before being incident on the beam combining mirror M10, so that the second remaining pumping light is reflected by the beam combining mirror M10 to the OPA for secondary pumping.

7. The laser system according to claim 1, characterized in that The second shaping mirror is provided with an aspherical surface for correcting the wavefront distortion of the second residual pump light.

8. The laser system according to claim 1, characterized in that A first laser lens f1 is further disposed between the laser beam splitter M1 and the first total reflection mirror M3.

9. The laser system according to claim 1, characterized in that A second laser lens f4 is disposed between the first beam splitter M9 and the beam combiner M10.

10. The laser system according to any one of claims 1 to 8, characterized in that: The OPO includes a first ZGP crystal, and the OPA includes a second ZGP crystal. Both the first ZGP crystal and the second ZGP crystal include a ZGP crystal slat and two copper heat sinks. The two copper heat sinks are respectively located on both sides of the ZGP crystal slat, and indium based on electromagnetic heating is used as a welding medium between the ZGP crystal and the copper heat sink.

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