Device and method for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering

Abstract

This invention provides a device and method for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering, belonging to the field of mid-infrared laser source technology. In this invention, the pump laser output from the pump laser is input into a Raman cell filled with Raman medium gas to achieve a 1.9 μm wavelength laser output. It is then focused by a focusing lens into a second Raman cell filled with Raman medium gas, and finally output from the Raman cell after multiple reflections by a Herroitt concave mirror. The laser undergoes multiple focusing processes within the Raman cell. This invention utilizes an existing high-pulse-energy Nd:YAG fundamental frequency laser as the pump source to pump the Raman medium, generating a 9.2 μm wavelength second-order Raman laser through hydrogen stimulated Raman scattering. Compared to other methods, this invention can achieve a relatively high pulse peak power and a relatively high laser pulse energy at 9.2 μm.

Description

Technical Field

[0001] This invention belongs to the field of high-precision laser optimization technology, and relates to a device and method for achieving 9.2μm mid-infrared laser output through stimulated Raman scattering. By converting the wavelength of a 1064nm laser into two stages, a 9.2-micrometer Raman laser output is achieved, which can be applied to infrared detection, long-distance transmission of lasers in the atmosphere, lidar detection and other fields. Background Technology

[0002] The 9.2μm wavelength laser source has immense value in laser technology applications. Currently, the main techniques for obtaining 9.2μm wavelength lasers include tunable CO2 gas lasers and mid-to-far-infrared OPO lasers. However, since 9.2μm is at the edge of the output of CO2 lasers, the output power or single-pulse energy is not ideal, and obtaining a narrow pulse width and high peak power 9.2μm laser through Q-switching is quite difficult. OPO is a method for obtaining wide-band laser tuning; OPO achieves a wide wavelength range, and some crystal media can obtain 9.2μm laser output through OPO. However, the beam quality of mid-infrared lasers obtained through OPO is relatively poor, with limited improvement capabilities. [Bai Zhenxu, Gao Jia, Zhao Chen, Yan Bingzheng, Qi Yaoyao, Ding Jie... & Lü Zhiwei. Research progress on long-wavelength infrared lasers based on nonlinear frequency conversion. Acta Optica Sinica.], [Yang Chao, et al. Research progress on mid-to-far-infrared high-power quantum cascade laser technology. Telemetry.]

[0003] Control, 43.04(2022):126-146.

[0004] Stimulated Raman scattering yields lasers with a wavelength of 9.2 μm, which have the advantage of relatively high peak pulse power. Currently, 1064 nm Nd:YAG lasers are relatively mature, with high output power and large single-pulse energy. 1064 nm lasers also have high beam quality.

[0005] Beam quality enhancement, as a convenient method, generates new wavelength laser light through stimulated Raman scattering, filtering out or converting higher-order transverse modes in the pump laser beam. The resulting Raman laser beam quality is significantly superior to that of the pump laser beam. This technique utilizes a cavity mirror design with long optical path multiple focusing to achieve Raman laser regeneration under low-pressure conditions, effectively avoiding laser ionization of gas, gas thermal lensing, and other nonlinear effects caused by the interaction between strong laser and the medium. Summary of the Invention

[0006] This invention differs from existing methods for obtaining 9.2 μm lasers using stimulated Raman spectroscopy. Existing methods typically employ high pulse energy or high hydrogen pressure to achieve 9.2 μm Raman laser output, without employing techniques to enhance the 9.2 μm laser; they simply focus the laser to obtain the output, resulting in very limited laser conversion efficiency, only around 1%. Research has found that the rotational Raman divergence radio frequency shift during hydrogen-stimulated Raman spectroscopy is 587 cm⁻¹. -1 It will be accompanied by a vibration frequency shift of 4155cm -1 Gain is generated by directly pumping hydrogen gas with a 1064nm laser to obtain a 1.9μm wavelength laser, while the 2.1μm rotating Raman laser also gains gain. As the pump laser energy continues to increase, the 2.1μm laser will gain continuous enhancement, forming a pulse energy competition with the 9.2μm laser.

[0007] This invention employs a cascaded Raman conversion method in two steps. The first step achieves high-efficiency 1.9μm Raman laser output. Then, the 1.9μm laser is used as a pump laser to pump hydrogen gas, achieving 9.2μm Raman laser output. Furthermore, this invention uses a 1.9 & 9.2μm HR / 2.1μm AR filter as a laser reflector to filter out the 2.1μm Raman laser, preventing gain amplification and promoting the conversion to the 9.2μm Raman laser.

[0008] This invention provides an apparatus and method for obtaining 9.2 μm mid-infrared laser light through stimulated Raman scattering. It combines stimulated Raman technology with spatial filtering, which removes higher-order modes, and Raman laser regeneration method to further optimize the laser beam.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A device for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering, the device comprising a pump laser 1, a Raman laser with a wavelength output of 1.9 μm, and a Raman laser with a wavelength output of 9.2 μm.

[0011] The pump laser 1 uses a 1064nm Nd:YAG solid-state Q-switched pulse laser as the pump laser source.

[0012] The Raman laser with a wavelength output of 1.9μm includes a Raman cell 3-1, a window 2-1, a window 2-2, a 0-degree mirror 4-1, a 0-degree mirror 4-2, a dichroic mirror 5, a laser recovery unit 6-1, and a Perinbrocca prism 7.

[0013] The Raman cell 3-1 is a hollow tubular container filled with high-pressure hydrogen gas, with a pressure range of 0.01-10 MPa. The Raman laser beam quality is optimized by adjusting the hydrogen gas pressure inside the Raman cell 3-1. The windows 2-1 and 2-2 are respectively installed at both ends of the Raman cell 3-1, with window 2-2 located at the end closer to the pump laser 1. The surfaces of the two windows are coated with laser antireflection films corresponding to the pump laser and Raman laser wavelengths, namely 1064 nm & 1.9 μm AR.

[0014] The 0-degree reflector 4-1 and 0-degree reflector 4-2 are respectively placed at both ends inside the Raman cell 3-1, with 0-degree reflector 4-1 facing window 2-1 and 0-degree reflector 4-2 facing window 2-2.

[0015] The dichroic mirror 5, the laser recovery unit 6-1, and the Perinbroca prism 7 are located outside the Raman cell 3-1, with the Perinbroca prism 7 located below the dichroic mirror 5 and the laser recovery unit 6-1 located behind the dichroic mirror 5.

[0016] With the central axis of the laser beam emitted by the pump laser 1 as the axis, it enters the Raman cell 3-1 through window 2-2. After two reflections by the 0-degree reflector 4-2 and 0-degree reflector 4-1, the laser beam is output to the outside of the Raman cell 3-1 after passing through window 2-1. After being split by the dichroic mirror 5, the 1064nm wavelength laser is transmitted and enters the laser collector 6-1. The 1.9μm laser is reflected and enters the Perinbroca prism 7. After being reflected by the Perinbroca prism 7, the propagation direction of the 1.9μm laser is turned by 90 degrees.

[0017] The Raman laser with a wavelength output of 9.2μm includes Raman cell 2 3-2, window 3 2-3, window 4 2-4, laser collector 2 6-2, laser collector 3 6-3, focusing lens 1 8-1, focusing lens 2 8-2, Herroitt concave mirror 1 9-1 and Herroitt concave mirror 2 9-2.

[0018] The Raman cell 2 3-2 is a hollow tubular container filled with high-pressure hydrogen gas at a pressure between 0.01 and 10 MPa. The Raman laser beam quality is optimized by adjusting the gas pressure of the Raman cell 2 3-2. The windows 3 2-3 and 4 2-4 are respectively installed at both ends of the Raman cell 2 3-2, with window 3 2-3 located at the end closest to the Perinbroka prism 7. Both windows are coated with laser antireflection films corresponding to the pump laser and Raman laser wavelengths, namely 1.9 μm and 9.2 μm AR.

[0019] The focusing lens 8-1 is located outside the Raman cell 3-2 and is positioned on the laser beam incident side of the window 2-3, and both are coaxial with the laser beam; the focusing lens 8-2 is located inside the Raman cell 3-2 and is positioned on the laser beam incident side of the window 2-4, and both are coaxial with the laser beam.

[0020] The Herroitt concave mirror 9-1 and Herroitt concave mirror 9-2 are respectively placed at both ends inside the Raman cell 3-2. Herroitt concave mirror 9-1 is placed opposite to window 2-3 and is confocal with focusing lens 8-1. Herroitt concave mirror 9-2 is placed opposite to window 2-4 and is confocal with focusing lens 8-2. The concave surfaces of Herroitt concave mirror 9-1 and Herroitt concave mirror 9-2 are coated with a 1.9μm & 9.2μm high reflectivity film for laser 0 degrees and have high transmission capability for 2.1μm laser, thus filtering out the 2.1μm laser generated in stimulated Raman scattering.

[0021] The laser recovery unit 2 6-2 and laser recovery unit 3 6-3 are located inside the Raman cell 2 3-2, and are respectively placed on the side of the 2.1μm laser filter of Herroitt concave mirror 2 9-2 and Herroitt concave mirror 1 9-1, for the recovery and consumption of 2.1μm wavelength laser.

[0022] The laser beam reflected by the Perinbroka prism 7 passes through the focusing lens 8-1 and window 2-3 and enters the Raman cell 3-2. In the Raman cell 3-2, the laser beam first illuminates the Herroitt concave mirror 9-1. The 1.9μm and 9.2μm laser beams are reflected by the Herroitt concave mirror 9-1 and then reflected by the Herroitt concave mirror 9-2. After being reflected by the Herroitt concave mirror 9-2, the laser beam passes through the focusing lens 8-2 and window 2-4 and is output to the outside of the Raman cell 3-2. At the same time, excess laser beams need to be filtered out. The 2.1μm wavelength laser beam passes through the Herroitt concave mirror 9-1 and Herroitt concave mirror 9-2 and enters the laser collector 6-2 and laser collector 6-3, where it is consumed.

[0023] The focal lengths of focusing lenses 8-1 and 8-2 must be matched with the length of Raman cell 3-2 and the curvatures of Herroitt concave mirrors 9-1 and 9-2. By adjusting the curvatures of the focusing lenses and Herroitt mirrors, as well as the length of Raman cell 3-2, the Raman laser beam quality is optimized. During placement, focusing lens 8-1 and Herroitt mirror 9-1 should be placed confocally. The laser beam is first focused by focusing lens 8-1 into the Raman medium. After reflection by Herroitt mirror 9-1, the laser beam is refocused and then illuminates Herroitt mirror 9-2, where it is reflected again. This process achieves a total of three focusing of the laser beam within Raman cell 3-2.

[0024] A method for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering, the method comprising the following steps:

[0025] Step 1: Fill Raman cell 3-1 and Raman cell 3-2 with hydrogen gas respectively.

[0026] Step 2: Adjust the optical path so that the 1064nm wavelength laser beam output by pump laser 1 is introduced into Raman cell 3-1 through window 2-2. After being reflected multiple times by 0-degree mirror 4-1 and 0-degree mirror 4-2 in Raman cell 3-1, the laser beam is output to the outside of Raman cell 3-1 through window 2-1.

[0027] Step 3: The output 1064nm laser and the generated 1.9μm Raman laser are filtered by the dichroic mirror 5, which reflects the 1.9μm Raman laser and allows the remaining 1064nm laser to pass through before entering the laser recovery unit 6-1; the 1.9μm Raman laser is then refracted by the dichroic mirror 5 and the Perinbroka prism 7 before entering the Raman laser with a wavelength output of 9.2μm.

[0028] Step four: The 1.9μm Raman laser reflected by the Perinbroka prism 7 passes through the focusing lens 8-1 and window 2-3, enters the Raman cell 3-2 and is focused. After being reflected twice by the two Herroitt concave mirrors, it is output to the outside of the Raman cell 3-2 through the focusing lens 8-2 and window 2-4. The laser beam is refocused each time it is reflected by the Herroitt concave mirror, achieving a total of three focusing in the Raman cell 3-2. During this process, the 2.1μm rotating Raman laser generated by the 1.9μm laser is filtered out by the two Herroitt concave mirrors and consumed by the two laser recovery devices. The remaining 1.9μm and 9.2μm dual-wavelength lasers are reflected and focused in the Raman cell 3-2, ultimately obtaining the 9.2μm mid-infrared laser.

[0029] The beneficial effects of this invention are:

[0030] This invention employs a cascaded Raman conversion method in two steps. The first step achieves high-efficiency 1.9μm Raman laser output. Then, the 1.9μm laser is used as a pump laser to pump hydrogen gas, achieving 9.2μm Raman laser output. Furthermore, this invention uses a 1.9 & 9.2μm HR / 2.1μm AR filter as a laser reflector to filter out the 2.1μm Raman laser, preventing gain amplification and promoting the conversion to the 9.2μm Raman laser. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the device structure of the present invention.

[0032] In the diagram: Pump laser 1; Window 1 2-1; Window 2 2-2; Window 3 2-3; Window 4 2-4; Raman cell 1 3-1; Raman cell 2 3-2; 0-degree mirror 1 4-1; 0-degree mirror 2 4-2; Dichroic mirror 5; Laser recoverer 1 6-1; Laser recoverer 2 6-2; Laser recoverer 3 6-3; Perinbrocca prism 7; Focusing lens 1 8-1; Focusing lens 2 8-2; Herroitt concave mirror 1 9-1; Herroitt concave mirror 2 9-2. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments.

[0034] Example

[0035] like Figure 1 The diagram shown is a schematic of the device structure of the present invention. In this embodiment, a solid-state Nd:YAG laser with an output wavelength of 1064nm is used as the pump source, which can output a single pulse of 900mJ laser.

[0036] according to Figure 1 The assembly device is as follows:

[0037] A device for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering includes a pump laser 1, a Raman laser with a wavelength output of 1.9 μm, and a Raman laser with a wavelength output of 9.2 μm.

[0038] The pump laser 1 uses a 1064nm Nd:YAG solid-state Q-switched pulse laser as the pump laser source.

[0039] The Raman laser with a wavelength output of 1.9μm includes a Raman cell 3-1, a window 2-1, a window 2-2, a 0-degree mirror 4-1, a 0-degree mirror 4-2, a dichroic mirror 5, a laser recovery unit 6-1, and a Perinbrocca prism 7.

[0040] The Raman cell 3-1 is a hollow tubular container with a length of 1.5m, and is filled with 2.5MPa hydrogen gas. The windows 2-1 and 2-2 are respectively installed at both ends of the Raman cell 3-1, and the window 2-2 is located at the end closer to the pump laser 1. Both windows are coated with 1064nm & 1.9μm AR.

[0041] The 0-degree reflector 4-1 and 0-degree reflector 4-2 are respectively placed at both ends inside the Raman cell 3-1, with 0-degree reflector 4-1 facing window 2-1 and 0-degree reflector 4-2 facing window 2-2.

[0042] With the central axis of the laser beam emitted by the pump laser 1 as the axis, it enters the Raman cell 3-1 through window 2-2. After two reflections by the 0-degree mirror 4-2 and 0-degree mirror 4-1, the laser beam is output to the outside of the Raman cell 3-1 after passing through window 2-1. After being split by the dichroic mirror 5, the 1064nm wavelength laser is transmitted. The transmitted laser enters the laser collector 6-1. The 1.9μm laser is reflected and enters the Perinbroca prism 7. After being reflected by the Perinbroca prism, the propagation direction of the 1.9μm laser is turned by 90 degrees.

[0043] The Raman laser with a wavelength output of 9.2μm includes Raman cell 2 3-2, window 3 2-3, window 4 2-4, laser collector 2 6-2, laser collector 3 6-3, focusing lens 1 8-1, focusing lens 2 8-2, Herroitt concave mirror 1 9-1 and Herroitt concave mirror 2 9-2.

[0044] The Raman cell 2 3-2 is a hollow tubular container, 1.3m long, filled with 0.5MPa hydrogen gas; the windows 3 2-3 and 4 2-4 are respectively installed at both ends of the Raman cell 2 3-2, and the window 3 2-3 is located at the end closer to the Perinbroka prism 7. Both windows are coated with 1.9μm & 9.2μm AR.

[0045] The focusing lens 8-1 is located outside the Raman cell 3-2 and is positioned on the laser beam incident side of window 2-3, and both are coaxial with the laser beam; the focusing lens 8-2 is located inside the Raman cell 3-2 and is positioned on the laser beam incident side of window 2-4, and both are coaxial with the laser beam. The focal length of both focusing lens 8-1 and focusing lens 8-2 is 0.5m.

[0046] The Herroitt concave mirror 9-1 and Herroitt concave mirror 9-2 both have a curvature of 1m and are placed at opposite ends inside Raman cell 3-2. Herroitt concave mirror 9-1 is placed opposite window 2-3 and is confocal with focusing lens 8-1. Herroitt concave mirror 9-2 is placed opposite window 2-4 and is confocal with focusing lens 8-2. The concave surfaces of Herroitt concave mirror 9-1 and Herroitt concave mirror 9-2 are coated with a 1.9μm & 9.2μm high-reflectivity film for lasers, and have high transmission capability for 2.1μm lasers, thus filtering out the 2.1μm laser generated in stimulated Raman scattering.

[0047] The laser recovery unit 2 6-2 and laser recovery unit 3 6-3 are located inside the Raman cell 2 3-2, and are respectively placed on the side of the 2.1μm laser filter of Herroitt concave mirror 2 9-2 and Herroitt concave mirror 1 9-1, for the recovery and consumption of 2.1μm wavelength laser.

[0048] The laser beam reflected by the Perinbroka prism 7 passes through the focusing lens 8-1 and window 2-3 and enters the Raman cell 3-2. The laser beam first illuminates the Herroitt concave mirror 9-1. The 1.9μm and 9.2μm laser beams are reflected by the Herroitt concave mirror 9-1 and then reflected by the Herroitt concave mirror 9-2. After being reflected by the Herroitt concave mirror 9-2, the laser beam passes through the focusing lens 8-2 and window 2-4 and is output to the outside of the Raman cell 3-2. At the same time, the 2.1μm laser beam enters the laser collector 6-2 and laser collector 6-3 respectively and is consumed.

[0049] During placement, the focusing lens 8-1 and the Herroitt concave mirror 9-1 are placed confocally. The laser is first focused by the focusing lens 8-1 and then focused into the Raman medium. After reflection by the Herroitt concave mirror 9-1, the laser is focused again and then illuminates the Herroitt concave mirror 9-2. The laser is then focused once more by reflection by the Herroitt concave mirror 9-2. In total, the laser beam is focused three times in the Raman cell 3-2.

[0050] A method for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering, the method comprising the following steps:

[0051] Step 1: Fill Raman cell 3-1 with 2.5 MPa of hydrogen gas and fill Raman cell 3-2 with 0.5 MPa of hydrogen gas.

[0052] Step 2: Adjust the optical path so that the 1064nm wavelength laser beam output by pump laser 1 is introduced into Raman cell 3-1 through window 2-2. After being reflected multiple times by 0-degree mirror 4-1 and 0-degree mirror 4-2 in Raman cell 3-1, the laser beam is output to the outside of Raman cell 3-1 through window 2-1.

[0053] Step 3: The output 1064nm laser and the generated 1.9μm Raman laser are filtered by the dichroic mirror 5, which reflects the 1.9μm Raman laser and allows the remaining 1064nm laser to pass through before entering the laser recovery unit 6-1; the 1.9μm Raman laser is then refracted by the dichroic mirror 5 and the Perinbroka prism 7 before entering the Raman laser with a wavelength output of 9.2μm.

[0054] Step four: The 1.9μm Raman laser reflected by the Perinbroka prism 7 passes through the focusing lens 8-1 and window 2-3, enters the Raman cell 3-2 and is focused. After being reflected twice by the two Herroitt concave mirrors, it is output to the outside of the Raman cell 3-2 through the focusing lens 8-2 and window 2-4. The laser beam is refocused each time it is reflected by the Herroitt concave mirror, achieving a total of three focusing in the Raman cell 3-2. During this process, the 2.1μm rotating Raman laser generated by the 1.9μm laser is filtered out by the two Herroitt concave mirrors and consumed by the two laser recovery devices. The remaining 1.9μm and 9.2μm dual-wavelength lasers are reflected and focused in the Raman cell 3-2, ultimately obtaining the 9.2μm mid-infrared laser.

[0055] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A device for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering, characterized in that, The device includes a pump laser (1), a Raman laser with a wavelength output of 1.9 μm, and a Raman laser with a wavelength output of 9.2 μm; The pump laser (1) uses a 1064nm Nd:YAG solid-state Q-switched pulse laser as the pump laser source; The Raman laser with a wavelength output of 1.9μm includes Raman cell one (3-1), window one (2-1), window two (2-2), 0-degree mirror one (4-1), 0-degree mirror two (4-2), dichroic mirror (5), laser recovery unit one (6-1) and Perinbrocca prism (7). The Raman cell one (3-1) is a hollow tubular container filled with high-pressure hydrogen gas with a pressure range of 0.01-10MPa. The windows one (2-1) and two (2-2) are respectively installed at both ends of the Raman cell one (3-1), and the window two (2-2) is located at the end closer to the pump laser (1). The surfaces of the two windows are coated with laser anti-reflection films corresponding to the pump laser and Raman laser wavelengths, namely 1064nm and 1.9μmAR. The 0-degree reflector one (4-1) and 0-degree reflector two (4-2) are respectively placed at both ends inside the Raman cell one (3-1), and 0-degree reflector one (4-1) is placed opposite to window one (2-1), and 0-degree reflector two (4-2) is placed opposite to window two (2-2); The dichroic mirror (5), laser recovery unit (6-1), and Perinbroca prism (7) are located outside the Raman cell (3-1), with the Perinbroca prism (7) located below the dichroic mirror (5) and the laser recovery unit (6-1) located behind the dichroic mirror (5). With the central axis of the laser beam emitted by the pump laser (1) as the axis, it enters the Raman cell (3-1) through window two (2-2). After two reflections by the 0-degree mirror two (4-2) and the 0-degree mirror one (4-1), the laser beam is output to the outside of the Raman cell (3-1) after passing through window one (2-1). After being split by the dichroic mirror (5), the 1064nm wavelength laser is transmitted. The transmitted laser enters the laser recovery unit one (6-1), and the 1.9μm laser is reflected. The reflected laser enters the Perinbroca prism (7). After the 1.9μm laser is reflected by the Perinbroca prism (7), the propagation direction of the laser is turned by 90 degrees. The Raman laser with a wavelength output of 9.2μm includes Raman cell 2 (3-2), window 3 (2-3), window 4 (2-4), laser collector 2 (6-2), laser collector 3 (6-3), focusing lens 1 (8-1), focusing lens 2 (8-2), Herroitt concave mirror 1 (9-1) and Herroitt concave mirror 2 (9-2). The second Raman cell (3-2) is a hollow tubular container filled with high-pressure hydrogen gas at a pressure between 0.01 and 10 MPa. The third window (2-3) and the fourth window (2-4) are respectively installed at both ends of the second Raman cell (3-2), and the third window (2-3) is located at the end closest to the Perinbroka prism (7). Both windows are coated with laser antireflection films corresponding to the pump laser and Raman laser wavelengths, namely 1.9 μm and 9.2 μm AR. The first focusing lens (8-1) is located outside the second Raman cell (3-2), placed on the laser beam incident side of the third window (2-3), and both are coaxial with the laser beam; the second focusing lens (8-2) is located inside the second Raman cell (3-2), placed on the laser beam incident side of the fourth window (2-4), and both are coaxial with the laser beam. The Herroitt concave mirror one (9-1) and Herroitt concave mirror two (9-2) are respectively placed at both ends inside Raman cell two (3-2). Herroitt concave mirror one (9-1) is placed opposite to window three (2-3) and is confocal with focusing lens one (8-1). Herroitt concave mirror two (9-2) is placed opposite to window four (2-4) and is confocal with focusing lens two (8-2). The concave surfaces of Herroitt concave mirror one (9-1) and Herroitt concave mirror two (9-2) are coated with 1.9μm and 9.2μm high reflectivity films for laser 0 degrees, respectively, and have high transmission capability for 2.1μm lasers, thus filtering out the 2.1μm laser generated in stimulated Raman scattering. The laser recovery unit 2 (6-2) and laser recovery unit 3 (6-3) are located inside the Raman cell 2 (3-2), and are respectively placed on the side of the 2.1μm laser filter of Herroitt concave mirror 2 (9-2) and Herroitt concave mirror 1 (9-1), for the recovery and consumption of 2.1μm wavelength laser. The laser beam reflected by the Perinbrocca prism (7) passes through the focusing lens (8-1) and window (2-3) and enters the Raman cell (3-2). In the Raman cell (3-2), the laser beam first illuminates the Herroitt concave mirror (9-1). The 1.9μm and 9.2μm laser beams are reflected by the Herroitt concave mirror (9-1) and then reflected to the Herroitt concave mirror (9-2). 2) After being reflected by Herroitt concave mirror two (9-2), the laser beam passes through focusing lens two (8-2) and window four (2-4) in sequence and is output to the outside of Raman cell two (3-2). At the same time, the 2.1μm laser passes through Herroitt concave mirror one (9-1) or Herroitt concave mirror two (9-2) and enters laser collector two (6-2) or laser collector three (6-3) and is consumed. The focal lengths of the first focusing lens (8-1) and the second focusing lens (8-2) must match the length of the second Raman cell (3-2) and the curvatures of the first Herroitt concave mirror (9-1) and the second Herroitt concave mirror (9-2). The laser is first focused by the first focusing lens (8-1) into the Raman medium. After reflection by the first Herroitt concave mirror (9-1), the laser is focused again and then irradiates the second Herroitt concave mirror (9-2). The laser is then focused again by reflection by the second Herroitt concave mirror (9-2). In total, the laser beam is focused three times in the second Raman cell (3-2).

2. The device for achieving 9.2μm mid-infrared laser output via stimulated Raman scattering according to claim 1, characterized in that, Raman laser beam quality optimization is achieved by adjusting the air pressure inside Raman cell 1 (3-1), the air pressure inside Raman cell 2 (3-2), the curvature of the focusing lens and the Herroitt concave mirror, and the length of Raman cell 2 (3-2).

3. A method for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering, employing the apparatus for achieving 9.2 μm mid-infrared laser output via stimulated Raman scattering as described in claim 1 or 2, characterized in that, The method includes the following steps: Step 1: Fill Raman cell 1 (3-1) and Raman cell 2 (3-2) with hydrogen gas respectively; Step 2: Adjust the optical path so that the 1064nm wavelength laser beam output by the pump laser (1) is introduced into the Raman cell (3-1) through window 2 (2-2). After being reflected multiple times by the 0-degree mirror 1 (4-1) and the 0-degree mirror 2 (4-2) in the Raman cell (3-1), the laser beam is output to the outside of the Raman cell (3-1) through window 1 (2-1). Step 3: The output 1064nm laser and the generated 1.9μm Raman laser are filtered by a dichroic mirror (5), which reflects the 1.9μm Raman laser and allows the remaining 1064nm laser to pass through before entering the laser recovery unit (6-1). The 1.9μm Raman laser, after being refracted by the dichroic mirror (5) and the Perinbroka prism (7), enters the Raman laser with a wavelength output of 9.2μm. Step four: The 1.9μm Raman laser reflected by the Perinbroka prism (7) passes through the focusing lens one (8-1) and window three (2-3), enters the Raman cell two (3-2) and is focused. After being reflected twice by the two Herroitt concave mirrors, it is output to the outside of the Raman cell two (3-2) through the focusing lens two (8-2) and window four (2-4). The laser beam is refocused each time it is reflected by the Herroitt concave mirror, achieving a total of three focusing in the Raman cell two (3-2). During this period, the 2.1μm rotating Raman laser generated by the 1.9μm laser is filtered out by the two Herroitt concave mirrors and consumed by the two laser recovery devices. The 1.9μm and 9.2μm dual-wavelength lasers are retained and reflected and focused in the Raman cell two (3-2), finally obtaining the 9.2μm mid-infrared laser.

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