A raman laser outputting 9.2 μm far infrared laser

Abstract

This invention relates to the field of laser technology, and particularly to a Raman laser that outputs 9.2μm far-infrared laser light. It includes a laser pump beam splitting module, a first-order Raman laser generation module, a difference-frequency seed light preparation module, a laser beam combining and tuning module, a second-order Raman amplification module, and a laser collimation and separation module arranged sequentially along the optical path. The laser pump beam splitting module is used to achieve beam splitting and control of the 1064nm laser; the first-order Raman laser generation module is used to generate a 1.9μm first-order Raman laser from hydrogen; the difference-frequency seed light preparation module is used for difference-frequency preparation of the 9.2μm Raman seed light; the laser beam combining and tuning module is used for spatiotemporal overlap and beam combining of the pump light and the seed light; the second-order Raman amplification module is used for Raman amplification of the 9.2μm laser; and the laser collimation and separation module is used for collimation and separation of the target laser output. This invention utilizes a difference-frequency method to generate wavelength-matched far-infrared Raman seed light, and performs Raman amplification to ultimately obtain a 9.2μm far-infrared Raman laser with high pulse energy and high peak power.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a Raman laser that outputs 9.2μm far-infrared laser light. Background Technology

[0002] The 8-30 μm wavelength range is the far-infrared band, where many organic molecules' fingerprint absorption regions lie, making it a suitable light source for molecular detection. The 8-12 μm range is also an important atmospheric transmission window, especially the 9 μm band, which has a very high atmospheric transmission rate; therefore, it can be used as a light source for remote sensing. Current methods for generating far-infrared lasers include quantum cascade lasers, optical parametric lasers, and carbon dioxide lasers. Quantum cascade lasers primarily generate continuous-wave lasers and possess a certain range of wavelength tuning characteristics; optical parametric lasers also have the advantage of continuously tunable wavelengths, but their pulse energy and peak power are limited, failing to meet the requirements of applications such as differential absorption radar. Carbon dioxide lasers have very high pulse energy and peak power, but their strong spectral range is mainly concentrated in a few regions within the 9.3-10.6 μm band. Besides the methods mentioned above, stimulated Raman spectroscopy is also an important method for generating far-infrared lasers. However, as the Raman laser wavelength increases, the Raman laser gain coefficient decreases significantly, thereby greatly increasing the Raman laser threshold and affecting its conversion efficiency. Therefore, it is usually necessary to inject Raman seed light to lower the threshold of far-infrared Raman laser and improve its conversion efficiency. The most conventional method is to generate seed laser using optical parametric laser technology. However, this method faces the challenge of requiring fine-tuning of the spectrum to achieve a precise match between the wavelength of the seed light and the Raman light, which complicates the tuning of the far-infrared Raman laser. Summary of the Invention

[0003] To address the aforementioned problems, the present invention aims to provide a Raman laser that outputs 9.2μm far-infrared laser light, solving the problems of difficult wavelength matching, low conversion efficiency, and insufficient pulse energy and peak power of traditional far-infrared Raman laser seed light, while achieving the effects of simplified light source structure, convenient adjustment, and improved stability.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a Raman laser that outputs 9.2μm far-infrared laser light, comprising a laser pump beam splitting module, a first-order Raman laser generation module, a difference-frequency seed light preparation module, a laser beam combining and tuning module, a second-order Raman amplification module, and a laser collimation and separation module arranged sequentially along the optical path. The laser pump beam splitting module is used to achieve beam splitting and control of the 1064nm laser; the first-order Raman laser generation module is used to generate a 1.9μm first-order Raman laser from hydrogen gas; the difference-frequency seed light preparation module is used for difference-frequency preparation of the 9.2μm Raman seed light; the laser beam combining and tuning module is used for spatiotemporal overlap and beam combining of the pump light and the seed light; the second-order Raman amplification module is used for Raman amplification of the 9.2μm laser; and the laser collimation and separation module is used for collimation and separation of the target laser output, ultimately obtaining a 9.2μm far-infrared Raman laser with high pulse energy and high peak power.

[0006] The laser pump beam splitting module includes a laser and a beam splitter I. The laser is used to output a horizontally linearly polarized 1064nm pulsed laser. The beam splitter I is placed on the optical output path of the laser and splits the 1064nm pulsed laser into a 100mJ-level beam and a main pump beam.

[0007] The first-order Raman laser generation module includes a focusing lens I, a hydrogen Raman cell I, a collimating lens I, and a beam splitter II arranged sequentially along the optical path. The focusing lens I is used to focus the main pump beam into the hydrogen Raman cell I. The main pump beam is generated into a 1.9μm first-order Raman laser by hydrogen Raman scattering in the hydrogen Raman cell I. After being collimated by the collimating lens I, the 1.9μm first-order Raman laser is further split by the beam splitter II into a 1.9μm difference frequency beam and a 1.9μm Raman laser.

[0008] The difference frequency seed light preparation module includes a high-reflection mirror I, a half-wave plate, a dichroic mirror I, a difference frequency crystal I, and a difference frequency crystal II arranged sequentially along the optical path;

[0009] The 100mJ-level beam passes sequentially through a high-reflection mirror I and a half-wave plate for deflection and polarization conversion. It then passes through a dichroic mirror I and is combined with a 1.9μm difference-frequency beam, which is then incident on a difference-frequency crystal I. The difference-frequency crystal I generates a 2.4μm idler light through the difference-frequency process, which is then incident on a difference-frequency crystal II. The difference-frequency crystal II generates a 9.2μm seed light through the difference-frequency process.

[0010] The high-reflection mirror I is a 45° high-reflection mirror; the half-wave plate changes the polarization direction of the 100mJ-level beam to vertical polarization; the dichroic mirror I is set to be highly transparent to horizontally polarized 1.9μm lasers and highly reflective to vertically polarized 1064nm lasers.

[0011] The angle of the difference frequency crystal I is adjusted to phase matching, and vertically polarized 2.4μm idler light is generated through the difference frequency process, while the 1.9μm laser is amplified accordingly in the process;

[0012] Adjust the angle of the difference frequency crystal II to phase match, and generate horizontally polarized 9.2μm seed light through the difference frequency process.

[0013] The laser beam combining and tuning module includes an anti-reflection focusing lens, a high-reflection mirror II, a focusing lens II, a high-reflection mirror III, and a dichroic mirror II. The high-reflection mirror II, the focusing lens II, and the high-reflection mirror III are sequentially arranged in the optical path of the 1.9μm Raman laser for redirection-focusing-redirection of the 1.9μm Raman laser and directing it into the dichroic mirror II. The anti-reflection focusing lens is used to focus the 9.2μm seed light onto the dichroic mirror II. The dichroic mirror II is used to combine the 9.2μm seed light with the 1.9μm Raman laser and focus it onto the second-order Raman amplification module.

[0014] The second-order Raman amplification module includes a hydrogen Raman cell II. By adjusting the hydrogen pressure inside the cell, the hydrogen Raman cell II avoids laser-induced breakdown, prolongs the interaction time between the light and the medium, and achieves efficient Raman amplification of the 9.2μm seed light, thereby improving the laser pulse energy and peak power.

[0015] The laser collimation and separation module includes a collimating lens II and a dichroic mirror III arranged sequentially along the optical path. The collimating lens II is used for collimating the 9.2μm laser, and the dichroic mirror III is used for separating the 9.2μm laser from the remaining 1.9μm laser.

[0016] The collimating lens II is coated with a 9.2μm laser antireflection coating; the dichroic mirror III is coated with a 9.2μm laser antireflection coating and a 1.9μm laser high reflectivity coating.

[0017] The present invention has the following beneficial effects and advantages:

[0018] 1. Precise matching of seed light wavelength with low adjustment difficulty: 9.2μm seed light is generated by using a 1064nm laser and a 1.9μm first-order Raman laser of hydrogen gas through two difference frequencies. This process is equivalent to the second-order Raman process of 1064nm pumping hydrogen gas. The precise matching of the wavelength of seed light and Raman light can be achieved without fine tuning, which greatly reduces the difficulty of operation and adjustment.

[0019] 2. High conversion efficiency and excellent output performance: Through beam splitting design, the pump light is rationally distributed, and finally, a 9.2μm far-infrared laser with high pulse energy and high peak power can be output.

[0020] 3. Avoiding laser-induced breakdown and superior beam quality: By adjusting the focal length of the focusing lens, the length of the Raman cell, and the hydrogen gas pressure, and using photon conservation as the criterion, laser-induced breakdown in the Raman cell is effectively avoided; moreover, the beam quality of the 1.9μm Raman laser is better than that of the 1064nm pump laser, providing high-quality pump light for subsequent Raman amplification.

[0021] 4. Simple structure and high stability: The optical path design is simple. The laser beam combining and reflection are achieved through dichroic mirrors and high-reflection mirrors. The Raman conversion efficiency is improved through Herriot cavity. The overall device has high stability, narrow spectral line and can work continuously for a long time.

[0022] 5. Wide range of applications: The output 9.2μm far-infrared laser is located in the high-efficiency atmospheric transmission band and the organic molecule fingerprint absorption region, and can be widely used in molecular detection, remote sensing, environmental monitoring, lidar and other fields.

[0023] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0026] Figure 1 This is a schematic diagram of the structure of a Raman laser that outputs 9.2μm far-infrared laser according to the present invention.

[0027] In the diagram: 1. Laser; 2. Beam splitter I; 3. Focusing lens I; 4. Hydrogen Raman cell I; 5. Collimating lens I; 6. Beam splitter II; 7. High-reflection mirror I; 8. Half-wave plate; 9. Dichroic mirror I; 10. Differential frequency crystal I; 11. Differential frequency crystal II; 12. Anti-reflection coating focusing lens; 13. High-reflection mirror II; 14. Focusing lens II; 15. High-reflection mirror III; 16. Dichroic mirror II; 17. Hydrogen Raman cell II; 18. Collimating lens II; 19. Dichroic mirror III. Detailed Implementation

[0028] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0030] See Figure 1 As shown, this invention provides a Raman laser that outputs 9.2μm far-infrared laser light, comprising a laser pump beam splitting module, a first-order Raman laser generation module, a difference-frequency seed light preparation module, a laser beam combining and tuning module, a second-order Raman amplification module, and a laser collimation and separation module arranged sequentially along the optical path. The laser pump beam splitting module is used to achieve beam splitting and control of the 1064nm laser; the first-order Raman laser generation module is used to generate a 1.9μm first-order Raman laser from hydrogen gas; the difference-frequency seed light preparation module is used for difference-frequency preparation of the 9.2μm Raman seed light; the laser beam combining and tuning module is used for spatiotemporal overlap and beam combining of the pump light and the seed light; the second-order Raman amplification module is used for Raman amplification of the 9.2μm laser; and the laser collimation and separation module is used for collimation and separation of the target laser output, ultimately obtaining a 9.2μm far-infrared Raman laser with high pulse energy and high peak power.

[0031] In an embodiment of the present invention, the laser pump beam splitting module includes a laser 1 and a beam splitter I2, wherein the laser 1 is used to output a horizontally linearly polarized 1064nm pulsed laser, and the beam splitter I2 is disposed on the optical output path of the laser 1, and splits the 1064nm pulsed laser into a 100mJ-level beam and a main pump beam.

[0032] Preferably, laser 1 is a pulse-modulated Nd:YAG laser, outputting a horizontally linearly polarized 1064nm laser. The pulse energy of the 1064nm laser is typically above 1J, the pulse duration is on the order of 10ns, the beam quality M2 is typically less than 4, and the laser exit spot diameter is 8~10mm. The beam splitting ratio of beam splitter I2 is controlled according to the pulse energy of the 1064nm laser, splitting the 1064nm pump beam into two parts, one strong and one weak. The pulse energy of the weaker beam is maintained on the order of ~100mJ, while the remaining energy is focused into the first-order Raman laser generation module.

[0033] In an embodiment of the present invention, the first-order Raman laser generation module includes a focusing lens I3, a hydrogen Raman cell I4, a collimating lens I5, and a beam splitter II6 arranged sequentially along the optical path. The focusing lens I3 is used to focus the main pump beam into the hydrogen Raman cell I4. The main pump beam is generated into a 1.9μm first-order Raman laser by hydrogen Raman scattering in the hydrogen Raman cell I4. After the 1.9μm first-order Raman laser is collimated by the collimating lens I5, it is then split a second time by the beam splitter II6 into a 1.9μm difference frequency beam and a 1.9μm Raman laser.

[0034] Specifically, the focal length of focusing lens I3, the length of hydrogen Raman cell I4, and the hydrogen pressure are controlled based on the 1064nm laser pulse energy (peak power) and beam quality to ensure that the 1064nm laser is focused within hydrogen Raman cell I4 and laser-induced breakdown does not occur. The criterion is whether the total number of photons of various Raman lights and the remaining pump light generated after passing through hydrogen Raman cell I4 is conserved after window loss correction. If the total number of photons is basically conserved, no significant laser-induced breakdown has occurred. If the 1064nm laser pulse energy is large (high peak power) and the beam quality is good, an appropriate lens focal length is required. The focal length of focusing lens I3 can reach up to 3m, and the hydrogen pressure should be appropriately reduced, with a minimum of 1.1 atmospheres. The length of hydrogen Raman cell I4 needs to be controlled at 1.5 to 2 times the focal length of focusing lens I3. Collimating lens I5 collimates the generated 1.9μm Raman laser into parallel light, and a small amount (~10mJ) of 1.9μm is split off by beam splitter II6 for difference frequency, while the majority of the remaining 1.9μm laser is used as the pump laser for the second Raman process.

[0035] In this embodiment, a 1064nm laser with a beam quality of 900mJ or higher is focused into a hydrogen Raman cell I4 using a lens with a length of 2-3.0m. The length of the hydrogen Raman cell I4 is in the range of 3.5-4.5m, and the hydrogen pressure inside the hydrogen Raman cell I4 is controlled in the range of 1.1-3 atm. Appropriate hydrogen pressure and focal length conditions ensure that no significant laser-induced breakdown occurs (i.e., the sum of the Raman photon number and the remaining pump photon number exceeds 95% of the initial pump photon number injected into the Raman cell). At this point, a high-beam-quality 1.9μm Raman laser can be maintained, and the energy conversion of the 1.9μm Raman laser can be maintained above 40% (at least 360mJ). The BPP beam quality of the 1.9μm laser is essentially the same as that of the 1064nm laser; however, measured by M², the beam quality of the 1.9μm laser is significantly better than that of the 1064nm laser.

[0036] In an embodiment of the present invention, the difference-frequency seed light preparation module includes a high-reflection mirror I7, a half-wave plate 8, a dichroic mirror I9, a difference-frequency crystal I10, and a difference-frequency crystal II11 arranged sequentially along the optical path. A 100mJ-level beam passes sequentially through the high-reflection mirror I7 and the half-wave plate 8 for reversal and polarization conversion, then passes through the dichroic mirror I9 and is combined with a 1.9μm difference-frequency beam and incident on the difference-frequency crystal I10. The difference-frequency crystal I10 generates 2.4μm idler light through the difference-frequency process and is incident on the difference-frequency crystal II11. The difference-frequency crystal II11 generates 9.2μm seed light through the difference-frequency process.

[0037] Furthermore, the high-reflection mirror I7 is a 45° high-reflection mirror; the half-wave plate 8 changes the polarization direction of the 100mJ-level beam to vertical polarization; and the dichroic mirror I9 is ​​set to be highly transparent to horizontally polarized 1.9μm lasers and highly reflective to vertically polarized 1064nm lasers.

[0038] Specifically, the optical path is adjusted so that the strongest points of the 1064 nm and 1.9 μm pulses simultaneously reach the difference frequency crystal I10. KTP crystals are most commonly used, with a length of 2-4 cm and an aperture of 1 cm x 1 cm. The angle of the difference frequency crystal I10 is adjusted to achieve phase matching, generating a 2.4 μm idler light (on the order of ~20 mJ) with a vertical polarization direction through the difference frequency process. The 1.9 μm laser is correspondingly amplified (~30 mJ) during this process. The 1.9 μm and 2.4 μm lasers are then difference-frequencyd in the difference frequency crystal II11 (most commonly BaGaSe2 and Ag2GaSe2 crystals). The angle of the nonlinear crystal is adjusted to achieve phase matching, generating a 9.2 μm laser (on the order of ~200 μJ) with a horizontal polarization direction.

[0039] In an embodiment of the present invention, the laser beam combining and tuning module includes an antireflection focusing lens 12, a high-reflection mirror II 13, a focusing lens II 14, a high-reflection mirror III 15, and a dichroic mirror II 16. The high-reflection mirror II 13, the focusing lens II 14, and the high-reflection mirror III 15 are sequentially arranged in the optical path of the 1.9μm Raman laser for redirection-focusing-redirection of the 1.9μm Raman laser and are directed into the dichroic mirror II 16. The antireflection focusing lens 12 is used to focus the 9.2μm seed light onto the dichroic mirror II 16, and the dichroic mirror II 16 is used to combine the 9.2μm seed light with the 1.9μm Raman laser and focus it onto the second-order Raman amplification module.

[0040] Specifically, the positions of high-reflection mirrors II 13 and III 15 are adjusted to regulate the optical path, ensuring that the 1.9μm and 9.2μm beams coincide in both the temporal and spatial domains. The positions of the antireflection coating focusing lens 12 and focusing lens II 14 are adjusted to achieve optimal focal overlap between the 1.9μm pump light and the 9.2μm seed light.

[0041] In embodiments of the present invention, the second-order Raman amplification module includes a hydrogen Raman cell II17. The hydrogen Raman cell II17 avoids laser-induced breakdown by regulating the hydrogen pressure inside the cell, prolongs the interaction time between light and the medium, achieves efficient Raman amplification of 9.2μm seed light, and improves laser pulse energy and peak power.

[0042] Based on the pulse energy (peak power) and beam quality of the 1.9μm laser, the focal lengths of focusing lens II14 and antireflection focusing lens 12, as well as the hydrogen pressure in the Raman cell, are controlled to ensure that no significant laser-induced breakdown occurs within the Raman cell. The criterion is whether the total number of photons of all Raman light generated after passing through the Raman cell, as well as the remaining pump light, is conserved after window loss correction. If the total number of photons is basically conserved, no significant laser-induced breakdown has occurred. The hydrogen Raman cell II17 uses a Herriot-type cavity, and the number of passes is increased to improve the conversion efficiency of the 9.2μm Raman laser. Its energy conversion efficiency can typically reach ~15% (based on 350mJ 1.9μm, it can generate ~50mJ 9.2μm laser, with a pulse width of ~10ns and a peak power of ~5MW).

[0043] Specifically, the beam quality of the 1.9μm laser is far superior to that of the 9.2μm difference-frequency seed laser. Therefore, when selecting the lens focal length, the focal length of the anti-reflection focusing lens 12 needs to be significantly smaller than that of the focusing lens II 14 (typical focal length ratio: focal length of anti-reflection focusing lens 12 / focal length of focusing lens II 14 = 0.5~0.75) in order to achieve a good overlap of the focal points of the 1.9μm pump light and the 9.2μm seed light.

[0044] The focal length of the antireflective focusing lens 12 is typically in the range of 1.2 to 1.8 m, with a typical value of 1.5 m selected. The focal length of the focusing lens II 14 is selected in the range of 2.25 m to 3 m. The length of the hydrogen Raman cell II 17 is selected in the range of 2.25 m to 3 m, and the hydrogen pressure is in the range of 5 to 20 atm.

[0045] In an embodiment of the present invention, the laser collimation and separation module includes a collimating lens II 18 and a dichroic mirror III 19 arranged sequentially along the optical path, wherein the collimating lens II 18 is used for collimating the 9.2μm laser, and the dichroic mirror III 19 is used for separating the 9.2μm laser from the remaining 1.9μm laser.

[0046] Furthermore, the collimating lens II18 is coated with a 9.2μm laser antireflection film, and by adjusting its distance from the Raman cell, the collimation of the 9.2μm laser is achieved; the dichroic mirror III19 is coated with a 9.2μm laser antireflection film and a 1.9μm laser high reflection film, so as to achieve the separation of the 9.2μm laser from the remaining 1.9μm laser.

[0047] The present invention provides a Raman laser that outputs 9.2μm far-infrared laser light, the working principle of which is as follows:

[0048] During operation, the 1064nm laser is first split into two beams, one strong and one weak. A small portion of the 1064nm beam passes through a half-wave plate 8 to rotate its polarization direction by 90°. The main 1064nm beam is focused by focusing lens I3 and enters hydrogen Raman cell I4, generating a 1.9μm Raman laser. The 1.9μm Raman laser is again split into two beams, one strong and one weak. A small portion of the 1.9μm Raman laser, combined with the 1064nm laser, is injected into difference frequency crystal I10 to generate a difference frequency 2.4μm laser, while simultaneously amplifying the pulse energy of the 1.9μm Raman laser. The 1.9μm Raman laser and the generated 2.4μm laser are then subjected to difference frequency again in difference frequency crystal II11 to generate a 9.2μm seed beam. The 9.2μm seed beam and the strong 1.9μm beam are focused and combined, then injected together into a high-pressure hydrogen Raman cell II17 to achieve amplified 9.2μm far-infrared Raman laser.

[0049] This invention provides a Raman laser that outputs 9.2μm far-infrared laser light. It achieves high-energy, high-peak-power 9.2μm far-infrared laser output by combining two stimulated Raman processes and two optical difference-frequency physical processes. Specifically, a 2.4μm idler light is generated by the difference-frequency interaction between a 1064nm pump light and a first-order Raman laser (1.9μm) from hydrogen gas. This idler light corresponds precisely to the 4155cm Raman frequency shift of hydrogen gas. -1 A second frequency difference between 1.9 μm and 2.4 μm is performed to generate a 9.2 μm laser. These two frequency difference processes achieve precise wavelength matching of the hydrogen second-order Raman (9.2 μm) seed laser. Stimulated Raman amplification is then performed using the 1.9 μm laser as the pump light and the 9.2 μm laser as the seed light, resulting in a high-energy, high-peak-power 9.2 μm Raman laser, significantly reducing the difficulty of Raman laser adjustment. This invention features a simple structure, convenient adjustment, high stability, narrow spectral line, and high peak power.

[0050] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A Raman laser that outputs 9.2μm far-infrared laser light, characterized in that, The system comprises a laser pump beam splitting module, a first-order Raman laser generation module, a difference-frequency seed light preparation module, a laser beam combining and tuning module, a second-order Raman amplification module, and a laser collimation and separation module, arranged sequentially along the optical path. The laser pump beam splitting module is used to achieve beam splitting and control of the 1064nm laser; the first-order Raman laser generation module is used to generate a 1.9μm first-order Raman laser from hydrogen; the difference-frequency seed light preparation module is used for difference-frequency preparation of a 9.2μm Raman seed light; the laser beam combining and tuning module is used for spatiotemporal overlap and beam combining of the pump light and the seed light; the second-order Raman amplification module is used for Raman amplification of the 9.2μm laser; and the laser collimation and separation module is used for collimation and separation of the target laser output, ultimately obtaining a 9.2μm far-infrared Raman laser with high pulse energy and high peak power.

2. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 1, characterized in that, The laser pump beam splitting module includes a laser (1) and a beam splitter I (2), wherein the laser (1) is used to output a horizontally linearly polarized 1064nm pulsed laser, and the beam splitter I (2) is set on the optical output path of the laser (1) and splits the 1064nm pulsed laser into a 100mJ-level beam and a main pump beam.

3. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 2, characterized in that, The first-order Raman laser generating module includes a focusing lens I (3), a hydrogen Raman cell I (4), a collimating lens I (5), and a beam splitter II (6) arranged sequentially along the optical path. The focusing lens I (3) is used to focus the main pump beam into the hydrogen Raman cell I (4). The main pump beam is generated into a 1.9μm first-order Raman laser by hydrogen Raman scattering in the hydrogen Raman cell I (4). After the 1.9μm first-order Raman laser is collimated by the collimating lens I (5), it is then split into a 1.9μm difference frequency beam and a 1.9μm Raman laser by the beam splitter II (6).

4. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 3, characterized in that, The difference frequency seed light preparation module includes a high-reflection mirror I (7), a half-wave plate (8), a dichroic mirror I (9), a difference frequency crystal I (10), and a difference frequency crystal II (11) arranged sequentially along the optical path. The 100mJ beam passes through a high-reflection mirror I (7) and a half-wave plate (8) for reversal and polarization conversion, then passes through a dichroic mirror I (9) and is combined with a 1.9μm difference frequency beam and incident on a difference frequency crystal I (10). The difference frequency crystal I (10) generates a 2.4μm idler light through the difference frequency process and is incident on a difference frequency crystal II (11). The difference frequency crystal II (11) generates a 9.2μm seed light through the difference frequency process.

5. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 4, characterized in that, The high-reflection mirror I (7) is a 45° high-reflection mirror; the half-wave plate (8) changes the polarization direction of the 100mJ beam to vertical polarization; the dichroic mirror I (9) is set to be highly transparent to horizontally polarized 1.9μm laser and highly reflective to vertically polarized 1064nm laser.

6. The Raman laser with 9.2μm far-infrared laser output according to claim 4, characterized in that, The angle of the difference frequency crystal I (10) is adjusted to phase matching, and vertically polarized 2.4μm idler light is generated through the difference frequency process, and the 1.9μm laser is amplified accordingly in the process; Adjust the angle of the difference frequency crystal II (11) to phase match, and generate horizontally polarized 9.2μm seed light through the difference frequency process.

7. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 4, characterized in that, The laser beam combining and tuning module includes an anti-reflection focusing lens (12), a high-reflection mirror II (13), a focusing lens II (14), a high-reflection mirror III (15), and a dichroic mirror II (16). The high-reflection mirror II (13), the focusing lens II (14), and the high-reflection mirror III (15) are sequentially arranged in the optical path of the 1.9μm Raman laser for the purpose of turning, focusing, and turning the 1.9μm Raman laser, and directing it into the dichroic mirror II (16). The anti-reflection focusing lens (12) is used to focus the 9.2μm seed light onto the dichroic mirror II (16), and the dichroic mirror II (16) is used to combine the 9.2μm seed light with the 1.9μm Raman laser and focus it onto the second-order Raman amplification module.

8. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 7, characterized in that, The second-order Raman amplification module includes a hydrogen Raman cell II (17). The hydrogen Raman cell II (17) avoids laser-induced breakdown by adjusting the hydrogen pressure in the cell, prolongs the interaction time between the light and the medium, achieves efficient Raman amplification of the 9.2μm seed light, and improves the laser pulse energy and peak power.

9. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 7, characterized in that, The laser collimation and separation module includes a collimating lens II (18) and a dichroic mirror III (19) arranged sequentially along the optical path. The collimating lens II (18) is used for collimating the 9.2μm laser, and the dichroic mirror III (19) is used for separating the 9.2μm laser from the remaining 1.9μm laser.

10. The Raman laser that outputs 9.2μm far-infrared laser light according to claim 9, characterized in that, The collimating lens II (18) is coated with a 9.2 μm laser anti-reflection film; the dichroic mirror III (19) is coated with a 9.2 μm laser anti-reflection film and a 1.9 μm laser high reflection film.

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