Mid-infrared light parametric oscillator pumped by dual-wavelength nanosecond pulse solid laser

Abstract

The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulse solid laser can simultaneously output 1.9 micron laser and 2.1 micron laser, realizes broad spectrum / multi-wavelength output of the mid-infrared optical parametric oscillator, and can ensure that mid-infrared laser has excellent beam quality and relatively high output power. The output power of the 1.9 [mu] m optical fiber laser pumping source is hectowatt magnitude, and the 1.9 [mu] m optical fiber laser pumping source serves as a pumping source of a Ho crystal in the solid laser oscillator. In a Tm solid laser oscillator and a Ho solid laser oscillator, a resonant cavity comprises two plano-concave sub-cavities, the two plano-concave sub-cavities are a Tm crystal oscillation cavity and a Ho crystal oscillation cavity respectively, the two plano-concave sub-cavities share one output mirror, the Tm crystal oscillation cavity adopts a 793 nm semiconductor laser for pumping, and the Ho crystal oscillation cavity adopts a 1.9 [mu] m optical fiber laser pumping source I for pumping; in the phosphorus-germanium-zinc optical parametric oscillator, a planar four-mirror annular cavity is used as a single-resonance optical parametric oscillation cavity.

Description

Technical Field

[0001] The present invention relates to the technical field of lasers, and particularly to a mid-infrared optical parametric oscillator pumped by a dual-wavelength nanosecond pulsed solid-state laser. Background Art

[0002] The 3-5μm laser generated by a zinc germanium phosphide mid-infrared optical parametric oscillator is located in the atmospheric transmission window, with the characteristic of small atmospheric transmission loss, and covers the absorption peaks of water and various pollutant gases (such as CH4, NO2, etc.), and has broad application prospects in the fields of laser medicine, pollutant detection, etc. Another important application of the 3-5μm laser is optoelectronic interference and optoelectronic countermeasure in the military, playing an irreplaceable role in modern information warfare.

[0003] At present, the main technical approach to realizing the 3-5μm laser is to pump a holmium-doped solid-state laser with a thulium-doped fiber laser to achieve the output of 2μm laser, and then pump a zinc germanium phosphide optical parametric oscillator to achieve the output of mid-infrared laser. However, the zinc germanium phosphide optical parametric oscillator only outputs a single center wavelength signal light (typically about 3.9μm) and an idler light (typically about 4.6μm). In the field of pollutant detection, mid-infrared lasers with a wide spectrum / multiple wavelengths are often required to detect multiple gases simultaneously. Therefore, developing a dual-wavelength nanosecond pulsed solid-state laser as the pump source of the zinc germanium phosphide optical parametric oscillator can achieve the output of mid-infrared laser with a wide spectrum / multiple wavelengths, thereby expanding the application range of the optical parametric oscillator. Summary of the Invention

[0004] To overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide a mid-infrared optical parametric oscillator pumped by a dual-wavelength nanosecond pulsed solid-state laser, which can simultaneously output 1.9μm and 2.1μm lasers, realize the wide-spectrum / multiple-wavelength output of the mid-infrared optical parametric oscillator, and ensure that the mid-infrared laser has excellent beam quality and high output power.

[0005] The technical solution of the present invention is: a mid-infrared optical parametric oscillator pumped by a dual-wavelength nanosecond pulsed solid-state laser, which includes: a 1.9μm fiber laser pump source, a Tm, Ho solid-state laser oscillator, and a zinc germanium phosphide optical parametric oscillator;

[0006] The 1.9μm fiber laser pump source is a non-polarization-maintaining thulium-doped fiber laser, including a first-stage non-polarization-maintaining thulium-doped fiber oscillator and a first-stage large-mode-field thulium-doped fiber amplifier; the Tm, Ho solid-state laser oscillator includes a 793nm LD, a coupling lens, a Tm crystal, a Ho crystal, an acousto-optic modulation device, and a dichroic mirror used in cooperation; the zinc germanium phosphide optical parametric oscillator includes a coupling lens, a polarization rotation system, a zinc germanium phosphide crystal, and a dichroic mirror used in cooperation;

[0007] The output power of the 1.9-μm fiber laser pump source is in the order of hundreds of watts, which is used as the pump source for the Ho crystal in the solid laser oscillator. In the Tm, Ho solid laser oscillator, the resonant cavity includes two plano-concave sub-cavities, namely the Tm crystal oscillation cavity and the Ho crystal oscillation cavity. The two sub-cavities share an output mirror. The Tm crystal oscillation cavity is pumped by a 793-nm semiconductor laser, and the Ho crystal oscillation cavity is pumped by the 1.9-μm fiber laser pump source Ⅰ.

[0008] In the zinc germanium phosphide optical parametric oscillator, a planar four-mirror ring cavity is used as the single-resonant optical parametric oscillation cavity.

[0009] The present invention adopts a composite cavity type in which the Tm and Ho lasers share the same oscillator, and simultaneously outputs 1.9-μm and 2.1-μm nanosecond pulsed lasers. After pumping the zinc germanium phosphide optical parametric oscillator, it realizes the output of wide-spectrum / multi-wavelength mid-infrared lasers, expands the output spectral range of the zinc germanium phosphide optical parametric oscillator, and can ensure that the mid-infrared laser has excellent beam quality and high output power. Brief Description of the Drawings

[0010] Figure 1 It is a schematic structural diagram of the 1.9-μm fiber laser pump source of the mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser provided by the embodiment of the present invention.

[0011] Figure 2 It is a schematic structural diagram of the Tm, Ho solid laser oscillator of the mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser provided by the embodiment of the present invention.

[0012] Figure 3 It is a schematic structural diagram of the zinc germanium phosphide optical parametric oscillator of the mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser provided by the embodiment of the present invention. Detailed Embodiments

[0013] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0014] It should be noted that the term "including" and any variations thereof in the description, claims and the above-mentioned drawings of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment that includes a series of steps or units does not necessarily limit to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0015] As Figures 1 - 3 shown, this mid-infrared optical parametric oscillator pumped by a dual-wavelength nanosecond pulsed solid laser includes: a 1.9-μm fiber laser pump source, a Tm, Ho solid laser oscillator, and a zinc germanium phosphide optical parametric oscillator.

[0016] The 1.9-μm fiber laser pump source is a non-polarization-maintaining thulium-doped fiber laser, including a first-stage non-polarization-maintaining thulium-doped fiber oscillator and a first-stage large-mode-field thulium-doped fiber amplifier; the Tm, Ho solid laser oscillator includes a 793-nm LD, a coupling lens, a Tm crystal, a Ho crystal, an acousto-optic modulation device, and a dichroic mirror used in cooperation; the zinc germanium phosphide optical parametric oscillator includes a coupling lens, a polarization rotation system, a zinc germanium phosphide crystal, and a dichroic mirror used in cooperation.

[0017] The output power of the 1.9-μm fiber laser pump source is in the order of hundreds of watts and serves as the pump source for the Ho crystal in the solid laser oscillator; in the Tm, Ho solid laser oscillator, the resonator includes two plano-concave sub-cavities, namely the Tm crystal oscillation cavity and the Ho crystal oscillation cavity, which share an output mirror. The Tm crystal oscillation cavity is pumped by a 793-nm semiconductor laser, and the Ho crystal oscillation cavity is pumped by a 1.9-μm fiber laser pump source Ⅰ.

[0018] In the zinc germanium phosphide optical parametric oscillator, a plane four-mirror ring cavity is used as a single-resonant optical parametric oscillation cavity.

[0019] The present invention adopts a composite cavity type in which Tm and Ho lasers share the same oscillator, and simultaneously outputs 〈0000047〉1.9-μm and 2.1-μm nanosecond pulsed lasers. After pumping the zinc germanium phosphide optical parametric oscillator, it realizes wide-spectrum / multi-wavelength mid-infrared laser output, expands the output spectral range of the zinc germanium phosphide optical parametric oscillator, and can ensure that the mid-infrared laser has excellent beam quality and high output power.

[0020] Preferably, the 1.9-μm fiber laser pump source includes: a first semiconductor laser 1, a first fiber combiner 2, a high-reflectivity fiber grating 3, a first gain fiber 4, a low-reflectivity fiber grating 5, a fiber isolator 6, a second semiconductor laser 7, a second fiber combiner 8, a second gain fiber 9, a pump stripper 10, and a fiber end cap 11; the output end of the first semiconductor laser is connected to the pump fiber of the first fiber combiner, the input end of the signal fiber of the first fiber combiner and the unused pump fibers are cut at an angle of 8°, the output end of the first fiber combiner is connected to the input end of the high-reflectivity fiber grating, the output end of the high-reflectivity fiber grating is connected to the input end of the first gain fiber, the output end of the first gain fiber is connected to the input end of the low-reflectivity fiber grating, the output end of the low-reflectivity fiber grating is connected to the input end of the fiber isolator, the output end of the fiber isolator is connected to the input end of the second fiber combiner, the second semiconductor laser is connected to the pump fiber of the second fiber combiner, the unused pump fibers of the second fiber combiner are cut at an angle of 8°, the output end of the second fiber combiner is connected to the input end of the second gain fiber, the output end of the second gain fiber is connected to the input end of the pump stripper, the output end of the pump stripper is connected to the input end of the end cap, and the end cap outputs 1.9-μm laser light.

[0021] Preferably, the Tm, Ho solid laser oscillator includes a first convex lens 12, a second convex lens 13, a first dichroic mirror 14, a second dichroic mirror 15, a third dichroic mirror 16, a Ho crystal 17, a first zero-degree reflector 18, a third semiconductor laser 19, a third convex lens 20, a fourth convex lens 21, a fourth dichroic mirror 22, a Tm crystal 23, a second zero-degree reflector 24, a fifth dichroic mirror 25, a sixth dichroic mirror 26, an acousto-optic modulator 27, and a plano-concave transmissive mirror 28; a beam of 1.9-μm laser light emitted from the fiber end cap is incident on the coupling lens system composed of the first and second convex lenses, and after beam transformation, it is coupled into the Ho crystal through the first, second, and third dichroic mirrors to generate 2.1-μm signal light. The 2.1-μm signal light oscillates back and forth in the plano-concave resonant cavity composed of the first zero-degree reflector, the third dichroic mirror, the sixth dichroic mirror, and the plano-concave transmissive mirror, and finally is output by the plano-concave transmissive mirror; a beam of 79X-nm laser light emitted from the third semiconductor laser is incident on the coupling lens system composed of the third and fourth convex lenses, and after beam transformation, it is coupled into the Ho crystal through the fourth dichroic mirror to generate 1.9-μm signal light. The 1.9-μm signal light oscillates back and forth in the plano-concave resonant cavity composed of the second zero-degree reflector, the fourth dichroic mirror, the fifth dichroic mirror, the sixth dichroic mirror, and the plano-concave transmissive mirror, and finally is output by the plano-concave transmissive mirror; the acousto-optic modulator modulates the continuous laser light in the cavity into pulsed light.

[0022] Preferably, the ZnGeP₂ optical parametric oscillator includes a fifth convex lens 29, a half-wave plate 30, a thin-film polarizer 31, a seventh dichroic mirror 32, a ZnGeP₂ crystal 33, an eighth dichroic mirror 34, a ninth dichroic mirror 35, a twelfth dichroic mirror 36, and an eleventh dichroic mirror 37; the linearly polarized pulsed pump laser emitted from the plano-concave transmissive mirror is incident on the first convex lens. After the spot transformation by the fifth convex lens, the polarization direction of the polarized light is controlled by the polarization rotation system composed of the half-wave plate and the thin-film polarizer, and then it is coupled into the ZnGeP₂ crystal through the seventh dichroic mirror; the signal light propagates in the cavity in the order of the ZnGeP₂ crystal, the eighth dichroic mirror, the ninth dichroic mirror, the twelfth dichroic mirror, the seventh dichroic mirror, and the ZnGeP₂ crystal, and finally 3-5μm mid-infrared laser is output through the eighth dichroic mirror, and the signal light and the pump light separated by the eleventh dichroic mirror are output.

[0023] Preferably, the pump source is a 79Xnm semiconductor laser, and the output fiber is a single-mode fiber or a multi-mode fiber; the center wavelength of the non-polarization-maintaining thulium-doped fiber oscillator is 1.9μm; the center wavelength of the large-mode-field thulium-doped fiber amplifier is 1.9μm, and the output power is in the order of hundreds of watts.

[0024] Preferably, the first gain fiber is a quartz fiber doped with thulium rare-earth ions, the fiber type is a single-clad fiber or a double-clad fiber, and the fiber core diameter is 10μm; the second gain fiber is a quartz fiber doped with thulium rare-earth ions, the fiber type is a double-clad fiber, and the fiber core diameter is 10-50μm.

[0025] Preferably, the fiber devices and the fibers are coupled by fiber fusion splicing, and a low-refractive-index glue is coated on the fusion point after splicing.

[0026] Preferably, the Tm, Ho solid-state laser oscillator outputs laser wavelengths of 1.9μm and 2.1μm, the laser pulse width is 20-100ns, and the average power is 20-50W.

[0027] Preferably, the Tm crystal includes single-doped Tm crystals such as Tm:YAP and Tm:YAG, and the Ho crystal includes single-doped Ho crystals such as Ho:YAG and Ho:YLF.

[0028] Preferably, the radius of curvature of the plano-concave transmissive mirror is 500-1000mm, and the coating is 30%-70% transmissive for 1.9μm laser and 30%-70% transmissive for 2.1μm laser.

[0029] The content of the present invention will be described in more detail below.

[0030] The first semiconductor laser, the second semiconductor laser, and the third semiconductor laser are 79Xnm semiconductor lasers.

[0031] The first gain fiber is a non-polarization-maintaining thulium-doped single-mode gain fiber with a core diameter of 10 μm and a inner cladding diameter of 130 μm; the high-reflectivity fiber grating has a reflectivity of not less than 99.5% at 1908 nm; the low-reflectivity fiber grating has a reflectivity of 10% at 1908 nm.

[0032] The second gain fiber is a large-mode-area thulium-doped gain fiber with a core diameter of 25 μm and a cladding diameter of 400 μm, and the signal fiber of the fiber device is matched with the front and rear stages.

[0033] The cut angle of the fiber output end cap is selected to be greater than 8°, and the output end cap has a transmittance of greater than 99.5% for the laser wavelength.

[0034] The first dichroic mirror, the second dichroic mirror, the fourth dichroic mirror, and the fifth dichroic mirror have a high transmittance for the 793 nm pump light and a high reflectivity for the 1.9 μm laser; the third dichroic mirror and the sixth dichroic mirror have a high transmittance for the 1.9 μm laser and a high reflectivity for the 2.1 μm laser.

[0035] The first zero-degree mirror has a high transmittance for the 1.9 μm laser and a high reflectivity for the 2.1 μm laser; the second zero-degree mirror has a high transmittance for the 793 nm pump light and a high reflectivity for the 1.9 μm laser; the plano-concave transmissive mirror has a transmittance of 30%-70% for the 1.9 μm laser and a transmittance of 30%-70% for the 2.1 μm laser.

[0036] The seventh dichroic mirror and the eleventh dichroic mirror have a high transmittance for the 1.9 μm - 2.1 μm pump light and a high reflectivity for the 3 - 5 μm laser; the eighth dichroic mirror has a high transmittance for the 1.9 μm - 2.1 μm pump light, a transmittance of 40% for the 3 - 4 μm signal light, and a high transmittance for the 4 - 5 μm idler light; the ninth dichroic mirror and the twelfth dichroic mirror have a high reflectivity for the 3 - 4 μm signal light and a high transmittance for the 4 - 5 μm idler light and the 1.9 μm - 2.1 μm pump light.

[0037] The fiber laser module of the present invention adopts a fully fiberized fusion splicing method, which has a compact structure, stable performance, and is easy to package, and can realize the output of continuous laser of 1.9 μm at the hundred-watt level. The Tm, Ho solid laser oscillator adopts a compound cavity type and can realize the output of high-power linearly polarized nanosecond pulsed laser of 1.9 μm and 2.1 μm. The zinc germanium phosphide optical parametric oscillator consists of a planar ring cavity and can generate mid-infrared laser with better beam quality at high output power. At the same time, a polarization rotation system composed of a half-wave plate and a thin-film polarizer is used. On the one hand, it can adjust the polarization state of the polarized light, and on the other hand, it can control the injected pump power, avoiding the influence of the pulse width instability on the experiment when directly increasing the pump power in the previous stage system.

[0038] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. Mid-infrared optical parametric oscillator pumped by a dual-wavelength nanosecond pulsed solid-state laser, characterized in that: It includes: A 1.9-μm fiber laser pump source, a Tm, Ho solid laser oscillator, and a zinc germanium phosphide optical parametric oscillator; The 1.9-μm fiber laser pump source is a non-polarization-maintaining thulium-doped fiber laser, including a first non-polarization-maintaining thulium-doped fiber oscillator and a first large-mode-field thulium-doped fiber amplifier; the Tm, Ho solid laser oscillator includes a 793-nm LD, a coupling lens, a Tm crystal, a Ho crystal, an acousto-optic modulation device, and a dichroic mirror used in cooperation; the zinc germanium phosphide optical parametric oscillator includes a coupling lens, a polarization rotation system, a zinc germanium phosphide crystal, and a dichroic mirror used in cooperation; The output power of the 1.9-μm fiber laser pump source is in the order of hundreds of watts and serves as the pump source for the Ho crystal in the solid laser oscillator; in the Tm, Ho solid laser oscillator, the resonant cavity includes two plano-concave sub-cavities, namely the Tm crystal oscillation cavity and the Ho crystal oscillation cavity, which share an output mirror. The Tm crystal oscillation cavity is pumped by a 793-nm semiconductor laser, and the Ho crystal oscillation cavity is pumped by a 1.9-μm fiber laser pump source Ⅰ; in the zinc germanium phosphide optical parametric oscillator, a plane four-mirror ring cavity is used as a single-resonant optical parametric oscillation cavity.

2. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid-state laser according to claim 1, characterized in that: The 1.9-μm fiber laser pump source includes: a first semiconductor laser (1), a first fiber combiner (2), a high-reflectivity fiber grating (3), a first gain fiber (4), a low-reflectivity fiber grating (5), a fiber isolator (6), a second semiconductor laser (7), a second fiber combiner (8), a second gain fiber (9), a pump stripper (10), and a fiber end cap (11); the output end of the first semiconductor laser is connected to the pump fiber of the first fiber combiner. The signal fiber input end of the first fiber combiner and other unused pump fibers are cut at an 8° angle. The output end of the first fiber combiner is connected to the input end of the high-reflectivity fiber grating. The output end of the high-reflectivity fiber grating is connected to the input end of the first gain fiber. The output end of the first gain fiber is connected to the input end of the low-reflectivity fiber grating. The output end of the low-reflectivity fiber grating is connected to the input end of the fiber isolator. The output end of the fiber isolator is connected to the input end of the second fiber combiner. The second semiconductor laser is connected to the pump fiber of the second fiber combiner. Other unused pump fibers of the second fiber combiner are cut at an 8° angle. The output end of the second fiber combiner is connected to the input end of the second gain fiber. The output end of the second gain fiber is connected to the input end of the pump stripper. The output end of the pump stripper is connected to the input end of the end cap, and the end cap outputs 1.9-μm laser.

3. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser according to claim 2, characterized in that: The Tm, Ho solid laser oscillator includes a first convex lens (12), a second convex lens (13), a first dichroic mirror (14), a second dichroic mirror (15), a third dichroic mirror (16), a Ho crystal (17), a first zero-degree mirror (18), a third semiconductor laser (19), a third convex lens (20), a fourth convex lens (21), a fourth dichroic mirror (22), a Tm crystal (23), a second zero-degree reflection (24), a fifth dichroic mirror (25), a sixth dichroic mirror (26), an acousto-optic modulator (27), and a plano-concave transmissive mirror (28); A beam of 1.9 μm laser is emitted from the fiber end cap and incident on the coupling lens system composed of the first and second convex lenses. After beam transformation, it is coupled into the Ho crystal through the first, second, and third dichroic mirrors, generating a 2.1 μm signal light. The 2.1 μm signal light oscillates back and forth in the plano-concave resonant cavity composed of the first zero-degree mirror, the third dichroic mirror, the sixth dichroic mirror, and the plano-concave transmissive mirror, and finally is output by the plano-concave transmissive mirror; A beam of 79X nm laser is emitted from the third semiconductor laser and incident on the coupling lens system composed of the third and fourth convex lenses. After beam transformation, it is coupled into the Ho crystal through the fourth dichroic mirror, generating a 1.9 μm signal light. The 1.9 μm signal light oscillates back and forth in the plano-concave resonant cavity composed of the second zero-degree mirror, the fourth dichroic mirror, the fifth dichroic mirror, the sixth dichroic mirror, and the plano-concave transmissive mirror, and finally is output by the plano-concave transmissive mirror; The acousto-optic modulator modulates the continuous laser in the cavity into pulsed light.

4. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser according to claim 3, characterized in that: The ZnGeP₂ optical parametric oscillator includes a fifth convex lens (29), a half-wave plate (30), a thin-film polarizer (31), a seventh dichroic mirror (32), a ZnGeP₂ crystal (33), an eighth dichroic mirror (34), a ninth dichroic mirror (35), a twelfth dichroic mirror (36), an eleventh dichroic mirror (37); The linearly polarized pulsed pump laser emitted from the plano-concave transmissive mirror is incident on the first convex lens. After the spot transformation by the fifth convex lens, the polarization direction of the polarized light is controlled by the polarization rotation system composed of the half-wave plate and the thin-film polarizer, and then it is coupled into the ZnGeP₂ crystal through the seventh dichroic mirror; The propagation direction of the signal light in the cavity is successively the ZnGeP₂ crystal, the eighth dichroic mirror, the ninth dichroic mirror, the twelfth dichroic mirror, the seventh dichroic mirror, the ZnGeP₂ crystal, and finally 3 - 5 μm mid-infrared laser is output through the eighth dichroic mirror. The eleventh dichroic mirror separates the output signal light and pump light.

5. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser according to claim 4, characterized in that: The pump source is a 79X nm semiconductor laser, and the output fiber is a single-mode fiber or a multi-mode fiber; The center wavelength of the non-polarization-maintaining thulium-doped fiber oscillator is 1.9 μm; The center wavelength of the large-mode-field thulium-doped fiber amplifier is 1.9 μm, and the output power is in the order of hundreds of watts.

6. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser according to claim 5, characterized in that: The first gain fiber is a quartz fiber doped with thulium rare-earth ions, and the fiber type is a single-clad fiber or a double-clad fiber, and the fiber core diameter is 10 μm; The second gain fiber is a quartz fiber doped with thulium rare-earth ions, and the fiber type is a double-clad fiber, and the fiber core diameter is 10 - 50 μm.

7. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser according to claim 6, characterized in that: The optical fiber device and the optical fiber are coupled by optical fiber fusion splicing, and a low refractive index glue is coated on the fusion point after splicing.

8. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser according to claim 7, characterized in that: The Tm, Ho solid laser oscillator outputs laser wavelengths of 1.9 μm and 2.1 μm, the laser pulse width is 20 - 100 ns, and the average power is 20 - 50 W.

9. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid-state laser according to claim 8, wherein: The Tm crystal includes Tm:YAP and Tm:YAG single-doped Tm crystals, and the Ho crystal includes Ho:YAG and Ho:YLF single-doped Ho crystals.

10. The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulsed solid laser according to claim 9, characterized in that: The curvature radius of the plano-concave transmissive mirror is 500 - 1000 mm, and the coating has 30% - 70% transmission for 1.9 μm laser and 30% - 70% transmission for 2.1 μm laser.

Images