High power mid-infrared optical parametric oscillator amplifier device directly pumped by a tmlaser

Abstract

The application relates to a high-power mid-infrared optical parametric oscillation amplification device directly pumped by a Tm laser, and belongs to the technical field of high-power mid-infrared lasers. The device comprises a Tm:YLF seed laser, a Tm:YLF slab amplifier, a ZGP optical parametric oscillator and a ZGP optical parametric amplifier in sequence. The Tm:YLF seed laser outputs 1.908-micron fundamental light, the power of the 1.908-micron fundamental light is amplified through the Tm:YLF slab amplifier, and then the ZGP optical parametric oscillator and the ZGP optical parametric amplifier are directly pumped. The injection end and the output end of the Tm:YLF slab amplifier are both provided with a fundamental light coupling isolation system. A mid-infrared laser coupling isolation system is arranged between the ZGP optical parametric oscillator and the ZGP optical parametric amplifier. The ZGP optical parametric oscillator and the ZGP optical parametric amplifier are directly pumped by high-power Tm:YLF lasers, so that the power of the mid-infrared laser and the overall efficiency of the system are improved.

Description

Technical Field

[0001] This invention belongs to the field of high-power mid-infrared laser technology, specifically relating to a high-power mid-infrared optical parametric oscillation amplifier directly pumped by a Tm-doped laser. Background Technology

[0002] Mid-infrared lasers with wavelengths of 3–5 μm have broad application prospects in medicine, dental surgery, molecular spectroscopy, organic matter analysis, special material processing, and national defense. Mid-infrared solid-state lasers are mainly divided into two categories: mid-infrared direct lasing lasers (including fiber lasers) and their amplifiers based on energy level transitions, and mid-infrared optical parametric oscillators and amplifiers based on nonlinear frequency conversion. Currently, outputs at the tens of watts and hundreds of watts levels have been achieved, respectively. Further power increases are mainly limited by low system efficiency and high material absorption losses. Due to the significant difference between the wavelength of diode (LD) lasers used as primary pump sources and mid-infrared laser wavelengths, severe quantum defects occur, leading to serious thermal problems and ultimately resulting in performance degradation and difficulty in increasing power in mid-infrared solid-state lasers. Although techniques such as "co-band pumping," "cross-relaxation," "energy upconversion," and "cascade conversion" can partially improve the efficiency problem caused by wavelength differences in mid-infrared solid-state laser systems, high-power output still faces damage problems to laser gain materials and nonlinear crystals and their coatings. Therefore, it is necessary to select new technical routes and achieve a leapfrog increase in the output power of mid-infrared solid-state lasers through comprehensive measures such as improving system efficiency, increasing fundamental frequency output power, reducing thermal effects, reducing the absorption coefficient of nonlinear crystals and improving their internal quality, and increasing crystal size. Summary of the Invention

[0003] To address the shortcomings of existing technologies and solve the aforementioned problems, a high-power mid-infrared optical parametric oscillator amplifier directly pumped by a Tm-doped laser is proposed. This device employs a high-power Tm:YLF laser to directly pump a ZGP optical parametric oscillator and a ZGP optical parametric amplifier, thereby improving the power of the mid-infrared laser and the overall efficiency of the system.

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

[0005] A high-power mid-infrared optical parametric oscillator amplifier directly pumped by a Tm-doped laser comprises, in sequence, a Tm:YLF seed laser, a Tm:YLF slab amplifier, a ZGP optical parametric oscillator, and a ZGP optical parametric amplifier. The Tm:YLF seed laser outputs a 1.908μm fundamental frequency light, which is amplified by the Tm:YLF slab amplifier to achieve 1.908μm fundamental frequency light power, and then directly pumps the ZGP optical parametric oscillator and the ZGP optical parametric amplifier. The injection and output ends of the Tm:YLF slab amplifier are equipped with fundamental frequency optical coupling isolation systems, and the ZGP optical parametric oscillator and the ZGP optical parametric amplifier are equipped with a mid-infrared laser coupling isolation system.

[0006] The technical solution is further configured such that the Tm:YLF seed laser achieves fundamental frequency wavelength modulation through a Bragg volume grating and / or a etalon, keeping it away from the water vapor absorption peak to avoid damage, and achieves pulse output through an acousto-optic Q-switch, which is then injected into the Tm:YLF slab amplifier.

[0007] The technical solution is further configured such that the Tm:YLF seed laser is a Tm:YLF crystal pumped by an optical fiber coupled 793nm LD end face, and pulse modulation is achieved in its folded resonant cavity through an acousto-optic Q switch.

[0008] The technical solution is further configured such that the Tm:YLF slab amplifier includes a 793nm LD pump array and a Tm:YLF slab crystal, wherein the 793nm LD pump array is respectively disposed at both ends of the Tm:YLF slab crystal.

[0009] The technical solution is further configured such that the ZGP optical parametric oscillator adopts a double concave linear short cavity, which includes a resonant cavity mirror and a first ZGP crystal, wherein the resonant cavity mirror is a concave mirror.

[0010] The technical solution is further configured such that the ZGP optical parametric oscillator adopts a dual-crystal ring cavity, which includes two first ZGP crystals and multiple mirrors, with the two first ZGP crystals having the same cutting angle and being placed opposite each other.

[0011] The technical solution is further configured such that the ZGP optical parametric amplifier includes a second ZGP crystal, and the ZGP optical parametric amplifier and the ZGP optical parametric oscillator use the same Tm:YLF pump laser. The mid-infrared laser output by the ZGP optical parametric oscillator is coupled to the 1.908μm fundamental frequency light after being split by the Tm:YLF slab amplifier and then coupled to the second ZGP crystal.

[0012] The technical solution is further configured such that the fundamental frequency optical coupling isolation system comprises an isolation component and a fundamental frequency optical spot coupling component. The isolation component includes an isolator, a waveplate, a polarizer, and an absorption cell. The fundamental frequency optical spot coupling component is composed of spherical lenses and cylindrical lenses with different focal lengths. The isolator isolates the 1.908μm fundamental frequency light.

[0013] The technical solution is further configured such that the mid-infrared laser coupling isolation system comprises a mid-infrared isolation component and a mid-infrared laser spot coupling component. The isolation component includes an isolator, a waveplate, a polarizer, and an absorption cell. The spot coupling component is composed of spherical lenses with different focal lengths. The isolator isolates the mid-infrared laser.

[0014] The technical solution is further configured such that the Tm:YLF slab amplifier and the ZGP optical parametric amplifier adopt a multi-stage amplification structure, a fundamental frequency optical coupling isolation system is provided between adjacent Tm:YLF slab amplifier stages, and a mid-infrared laser coupling isolation system is provided between adjacent ZGP optical parametric amplifier stages.

[0015] The beneficial effects of this invention are:

[0016] 1. The ZGP optical parametric oscillator and ZGP optical parametric amplifier are directly pumped by a 1.908μm fundamental frequency light, instead of using a conventional 2μm Ho:YAG laser for indirect pumping. This reduces the energy loss caused by the conversion between the 1.9μm Tm laser and the 2μm Ho laser, reduces the size of the optical system, and improves the overall optical efficiency of the mid-infrared laser system from 0.793μm to 3-5μm.

[0017] 2. Using YLF crystal as the substrate material in Tm-doped lasers has better thermal properties (negative thermo-optic coefficient) than substrate materials such as YAP, avoiding the extremely short thermal focal length caused by thermal effects at high power, which leads to laser instability and performance degradation.

[0018] 3. A Tm:YLF slab amplifier is used to achieve high-power laser output with pulsed, linearly polarized, and narrow linewidth of 1.908μm. The Tm:YLF laser system adopts the master oscillation plus amplification (MOPA) technical route. The oscillation stage controls the wavelength through a volume Bragg grating (VBG) and / or a standard to keep it away from the water vapor absorption peak, and achieves kHz high repetition rate pulse output through an acousto-optic Q switch. The amplification stage achieves high average power output across multiple orders of magnitude through multi-stage amplification.

[0019] 4. The Tm:YLF laser system fully utilizes the "cross-relaxation" effect of the one-to-two conversion. By optimizing doping concentration, slab crystal configuration, pump design, and amplification extraction efficiency, it achieves high-efficiency output of 1.908μm fundamental frequency light. The ZGP optical parametric oscillator and amplifier achieve low-threshold, high-efficiency mid-infrared laser output of 3-5μm by reducing ZGP crystal absorption loss, increasing laser damage resistance threshold, and optimizing resonant cavity parameters. The conversion efficiency is improved from two aspects: fundamental frequency light, optical parametric oscillator, and amplifier, thereby improving the overall conversion efficiency of the mid-infrared laser. The final photon efficiency target is >100%.

[0020] 5. By using a high-power Tm:YLF laser to directly pump a ZGP optical parametric oscillator and a ZGP optical parametric amplifier, the power potential of mid-infrared lasers is expected to achieve a leapfrog improvement over the current technology level. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the high-power mid-infrared optical parametric oscillation amplifier device directly pumped by a Tm-doped laser used in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the Tm:YLF seed laser used in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the Tm:YLF slab amplifier used in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the ZGP optical parametric oscillator used in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of another embodiment of the ZGP optical parametric oscillator used in this invention.

[0026] In the attached diagram: 1-Tm: YLF seed laser, 101-First 793nm LD, 102-First Tm: YLF crystal, 103-Acousto-optic Q-switch, 104-Output mirror, 105-Second 793nm LD, 106-Second Tm: YLF crystal, 107-VBG, 201-First Tm: YLF slab amplifier, 202-Second Tm: YLF slab amplifier, 203-Tm: YLF slab crystal, 204-First 793nm LD pump array, 205-Second 793nm LD pump array, 3-ZGP optical parametric oscillator, 301-resonant cavity input mirror, 302-resonant cavity output mirror, 303-first ZGP crystal, 304-first ZGP crystal a, 305-first ZGP crystal b, 401-first ZGP optical parametric amplifier, 402-second ZGP optical parametric amplifier, 5-fundamental frequency optical coupling isolation system, 6-mid-infrared laser coupling isolation system, 7-first beam splitter, 8-first reflector, 9-third beam splitter, 10-second beam splitter, 11-second reflector, 12-third reflector, 13-fourth reflector, 14-fifth reflector, 15-sixth reflector, 16-fourth beam splitter. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0028] Example 1:

[0029] like Figure 1 As shown, a high-power mid-infrared optical parametric oscillator amplifier directly pumped by a Tm-doped laser includes, in sequence, a Tm:YLF seed laser 1, a Tm:YLF slab amplifier, a ZGP optical parametric oscillator 3, and a ZGP optical parametric amplifier. The Tm:YLF seed laser 1 outputs a 1.908μm fundamental frequency light, which is amplified by the Tm:YLF slab amplifier and then directly pumps the ZGP optical parametric oscillator and the ZGP optical parametric amplifier. The injection and output ends of the Tm:YLF slab amplifier are equipped with a fundamental frequency optical coupling isolation system 5, and a mid-infrared laser coupling isolation system 6 is provided between the ZGP optical parametric oscillator 3 and the ZGP optical parametric amplifier.

[0030] The technical solution is further configured such that the Tm:YLF seed laser 1 achieves fundamental frequency wavelength modulation through a Bragg volume grating and / or a etalon, keeping it away from the water vapor absorption peak to avoid damage, and achieves pulse output through an acousto-optic Q switch, which is then injected into the Tm:YLF slab amplifier.

[0031] The technical solution is further configured such that the Tm:YLF seed laser 1 is a Tm:YLF crystal pumped by an optical fiber coupled 793nm LD end face, and pulse modulation is achieved in its folded resonant cavity through an acousto-optic Q switch.

[0032] Specifically, such as Figure 2 As shown, the Tm:YLF seed laser 1 includes a first 793nm LD 101, a second 793nm LD 105, a first Tm:YLF crystal 102, a second Tm:YLF crystal 106, an acousto-optic Q-switch 103, an output mirror 104, and a VBG (volume Bragg grating) 107. The center wavelength and linewidth of the output fundamental frequency light are controlled by the VBG 107 and / or the etalon, keeping it away from the water vapor absorption peak to avoid damage to optical components. The center wavelength is 1908±0.5nm, and the linewidth is <0.2nm. Pulse output from several kHz to tens of kHz is achieved through the acousto-optic Q-switch 103 within the cavity. Highly doped first Tm:YLF crystal 102 and second Tm:YLF crystal 106 are used as gain materials, ultimately achieving tens of watts of narrow-spectrum, linearly polarized 1.908μm fundamental frequency light output. The beam quality M... 2 <2, slope efficiency >60%, pulse width in the tens to hundreds of ns range.

[0033] Tm:YLF seed lasers are the most promising pump sources for high-power mid-infrared optical parametric oscillators and amplifiers. First, they possess a rich energy level structure, enabling wide-band tuning output near 2μm. Second, based on "cross-relaxation" and "co-band pumping" energy level structures, over 80% and over 90% slope efficiency outputs have been reported in the literature, respectively. Third, the long lifetime of the upper energy level is highly advantageous for achieving high-energy, high-peak-power pulsed laser output. Fourth, their natural birefringence effect allows for direct output of linearly polarized lasers. Fifth, their negative thermo-optical coefficient compensates for thermal lensing effects at high power, facilitating high-power, high-beam-quality laser output. Sixth, direct diode laser pumping is convenient and efficient, avoiding energy conversion losses in intermediate stages.

[0034] The technical solution is further configured such that the Tm:YLF slab amplifier includes a 793nm LD pump array and a Tm:YLF slab crystal, wherein the 793nm LD pump array is respectively disposed at both ends of the Tm:YLF slab crystal.

[0035] Specifically, such as Figure 3 As shown, the Tm:YLF slab amplifier includes a first 793nm LD pump array 204, a second 793nm LD pump array 205, and a Tm:YLF slab crystal 203. The first 793nm LD pump array 204 and the second 793nm LD pump array 205 are respectively disposed at both ends of the Tm:YLF slab crystal 203. Employing a dual-ended pumping and multi-pass amplification optical path, the doping concentration (typically 3%–6%), size (4mm × 10mm × 30mm in this embodiment), and pump beam configuration of the Tm:YLF slab crystal 203 can be optimized and adjusted according to the required amplification power and extraction efficiency.

[0036] This technical solution is further configured such that the Tm:YLF slab amplifier adopts a multi-stage amplification structure, and a fundamental frequency optical coupling isolation system 5 is provided between adjacent Tm:YLF slab amplifier stages. Specifically, the Tm:YLF slab amplifier (including the first Tm:YLF slab amplifier 201 and the second Tm:YLF slab amplifier 202) adopts a two-stage amplification structure. The first Tm:YLF slab amplifier 201 aims to amplify the 1.908μm fundamental frequency optical power by about 10 times, and the second Tm:YLF slab amplifier 202 aims to ultimately amplify the 1.908μm fundamental frequency optical power to tens to nearly one hundred times the output, with an overall optical-to-optical conversion efficiency close to 50%.

[0037] The technical solution is further configured such that the ZGP optical parametric oscillator 3 adopts a double concave linear short cavity, which includes a resonant cavity mirror and a first ZGP crystal, wherein the resonant cavity mirror is a concave mirror.

[0038] Specifically, such as Figure 4 As shown, the ZGP optical parametric oscillator 3 includes a resonant cavity mirror and a first ZGP crystal 303. The resonant cavity mirror includes a resonant cavity input mirror 301 and a resonant cavity output mirror 302. It employs a 1.908μm fundamental frequency light for reciprocating pumping, dual resonance, and a short, double-concave linear cavity to achieve low threshold and high-efficiency conversion. By rotating the cutting angle of the first ZGP crystal 303, wavelength tuning output in the mid-infrared range of 3–5μm can be achieved. When fully degenerate, it outputs a single 3.8μm laser. The goal of the ZGP optical parametric oscillator 3 is to achieve mid-infrared laser output in the tens of watts range, with a beam quality M... 2 <3, Conversion efficiency >60%.

[0039] The technical solution is further configured such that the ZGP optical parametric oscillator 3 adopts a dual-crystal ring cavity, which includes two first ZGP crystals and multiple mirrors. The two first ZGP crystals have the same cutting angle and are placed opposite each other.

[0040] Specifically, such as Figure 5As shown, the two first ZGP crystals are first ZGP crystal a304 and first ZGP crystal b305, respectively. First ZGP crystal a304 and first ZGP crystal b305 have the same cutting angle and are placed opposite each other. The 1.908μm fundamental frequency light passes through first ZGP crystal a304 and first ZGP crystal b305 in sequence to further improve the efficiency and power of mid-infrared laser.

[0041] The technical solution is further configured such that the ZGP optical parametric amplifier includes a second ZGP crystal, and the ZGP optical parametric amplifier and the ZGP optical parametric oscillator 3 use the same Tm:YLF pump laser. The mid-infrared laser output by the ZGP optical parametric oscillator 3 is coupled to the 1.908μm fundamental frequency light after being split by the Tm:YLF slab amplifier and then coupled to the second ZGP crystal.

[0042] ZGP crystal is one of the most widely used nonlinear crystals in mid-infrared optical parametric oscillators and amplifiers. Its outstanding advantages are: wide light transmission range, large effective nonlinear coefficient, high damage resistance threshold, high thermal conductivity, and large size. It has a very small absorption coefficient and a very high damage resistance threshold for the 1.908μm fundamental frequency light generated by Tm:YLF seed laser 1.

[0043] This technical solution is further configured such that the ZGP optical parametric amplifier adopts a multi-stage amplification structure, and a mid-infrared laser coupling isolation system 6 is provided between adjacent ZGP optical parametric amplifier stages. In this embodiment, the ZGP optical parametric amplifier (including the first ZGP optical parametric amplifier 401 and the second ZGP optical parametric amplifier 402) adopts a two-stage amplification structure. The mid-infrared laser output by the ZGP optical parametric oscillator 3 and the 1.908μm fundamental frequency light split by the Tm:YLF slab amplifier achieve optimal matching in space and propagation direction, thereby achieving efficient mid-infrared laser amplification. The second ZGP crystal has dimensions of 15mm×15mm×30mm and a fundamental frequency light absorption coefficient <0.03cm². -1 The mid-infrared laser absorption coefficient is <0.01cm. -1 Damage threshold >5 J / cm 2 The first ZGP optical parametric amplifier 401 aims to amplify the mid-infrared laser by about ten times, while the second ZGP optical parametric amplifier 402 aims to ultimately amplify the mid-infrared laser to tens of times or even higher, with an optical-to-optical conversion efficiency >50% and a beam quality M. 2 <5.

[0044] This technical solution is further configured such that the fundamental frequency optical coupling isolation system 5 comprises an isolation component and a fundamental frequency optical spot coupling component. The isolation component includes an isolator, a waveplate, a polarizer, and an absorption cell. The isolator isolates the 1.908μm fundamental frequency light. The function of the isolation component is to prevent the backlight from the subsequent stage from affecting the previous stage system, so that the 1.908μm fundamental frequency light propagates in one direction. The fundamental frequency optical spot coupling component is composed of spherical lenses and cylindrical lenses with different focal lengths. Its function is to adjust the shape and size of the 1.908μm fundamental frequency light injected into the Tm:YLF slab amplifier to the optimal value.

[0045] This technical solution is further configured such that the mid-infrared laser coupling isolation system 6 comprises a mid-infrared isolation component and a mid-infrared laser spot coupling component. The isolation component includes an isolator, a waveplate, a polarizer, and an absorption cell. The spot coupling component is composed of spherical lenses with different focal lengths. The isolator isolates the mid-infrared laser. The main function of the mid-infrared laser coupling isolation system 6 is to prevent the influence of the 3-5 μm mid-infrared backlight on the preceding system, and to adjust the spot shape and size of the 1.908 μm fundamental frequency light and the 3-5 μm mid-infrared laser to the optimal level, achieving spatial overlap and matching in the second ZGP crystal.

[0046] During operation, the Tm:YLF seed laser 1 outputs a 1.908μm fundamental frequency light as the seed light. This 1.908μm fundamental frequency light undergoes two stages of amplification: a first Tm:YLF slab amplifier 201 and a second Tm:YLF slab amplifier 202. After these two stages of amplification, the 1.908μm fundamental frequency light is split into a first reflected beam and a first transmitted beam by the first beam splitter 7. The first reflected beam is injected into the ZGP optical parametric oscillator 3 via the first reflecting mirror 8, outputting a 3-5μm mid-infrared laser. The first transmitted beam is then split into a second... Beam splitter 10 splits the beam into a second reflected beam and a second transmitted beam. The second reflected beam is transmitted sequentially through second reflector 11 and third reflector 12 to third beam splitter 9, and then coupled with 3-5μm mid-infrared laser beam to first ZGP optical parametric amplifier 401. The second transmitted beam is transmitted through fourth reflector 13, fifth reflector 14 and sixth reflector 15 to fourth beam splitter 16, and then coupled with 3-5μm mid-infrared laser beam amplified by first ZGP optical parametric amplifier 401 to second ZGP optical parametric amplifier 402.

[0047] This invention combines the advantages of a Tm:YLF seed laser 1 generating high-power, high-efficiency fundamental frequency light with a ZGP optical parametric oscillator 3 achieving low absorption and high-efficiency conversion, providing a new approach and method for achieving a super-scale leap in mid-infrared solid-state laser output power. The overall optical efficiency of the system is expected to exceed 20%, and the photon efficiency is expected to exceed 100%. At the same time, the number of Tm:YLF slab amplifiers and ZGP optical parametric amplifiers can be increased or decreased according to the required mid-infrared laser output power.

[0048] Example 2:

[0049] The difference between this embodiment and Embodiment 1 is that:

[0050] The pump sources for the Tm:YLF seed laser 1 and the Tm:YLF slab amplifier are Tm fiber or Er fiber, respectively, to achieve energy level... 3 H6→ 3 The F4 uses in-band pumping, rather than the "cross-relaxation" based on 793nm pumping. 3 H6+ 3 H4→ 3 F4+ 3 The purpose of the F4 energy level transition is to achieve high-power Tm:YLF laser output with higher efficiency, lower heat generation, and higher beam quality.

[0051] Example 3:

[0052] The difference between this embodiment and Embodiment 1 is that:

[0053] Nonlinear crystals employ quasi-phase-matched periodically polarized crystals such as MgO-doped PPLN or PPLT. In this case, it is necessary to improve the damage threshold of MgO:PPLN or PPLT and increase its effective light-transmitting aperture based on existing technology.

[0054] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of this application should still fall within the scope of the present invention.

Claims

1. A high-power mid-infrared optical parametric oscillation amplification device directly pumped by a Tm-doped laser, characterized in that, It sequentially includes a Tm:YLF seed laser, a Tm:YLF slab amplifier, a ZGP optical parametric oscillator, and a ZGP optical parametric amplifier. The Tm:YLF seed laser outputs 1.908μm fundamental frequency light, which is amplified by the Tm:YLF slab amplifier to achieve 1.908μm fundamental frequency light power, and then directly pumps the ZGP optical parametric oscillator and the ZGP optical parametric amplifier. The injection end and the output end of the Tm:YLF slab amplifier are equipped with a fundamental frequency optical coupling isolation system, and the ZGP optical parametric oscillator and the ZGP optical parametric amplifier are equipped with a mid-infrared laser coupling isolation system.

2. The high-power mid-infrared parametric oscillation amplification device directly pumped by a Tm-doped laser according to claim 1, characterized in that, The Tm:YLF seed laser achieves fundamental frequency wavelength modulation through a Bragg volume grating and / or etalon, and realizes pulse output through an acousto-optic Q-switch, which is then injected into the Tm:YLF slab amplifier.

3. The high-power mid-infrared parametric oscillation amplification device directly pumped by a Tm-doped laser according to claim 2, characterized in that, The Tm:YLF seed laser uses a fiber-coupled 793nm LD end-pumped Tm:YLF crystal, and pulse modulation is achieved through an acousto-optic Q-switch in its folded resonant cavity.

4. The high-power mid-infrared parametric oscillation amplification device directly pumped by a Tm-doped laser according to claim 3, characterized in that, The Tm:YLF slab amplifier includes a 793nm LD pump array and a Tm:YLF slab crystal, with the 793nm LD pump array disposed at both ends of the Tm:YLF slab crystal.

5. The high-power mid-infrared parametric oscillation amplification device directly pumped by a Tm-doped laser according to claim 1, characterized in that, The ZGP optical parametric oscillator adopts a double concave linear short cavity, which includes a resonant cavity mirror and a first ZGP crystal. The resonant cavity mirrors are all concave mirrors.

6. The high-power mid-infrared parametric oscillation amplifier directly pumped by a Tm-doped laser according to claim 1, characterized in that, The ZGP optical parametric oscillator adopts a dual-crystal ring cavity, which includes two first ZGP crystals and multiple mirrors. The two first ZGP crystals have the same cutting angle and are placed opposite each other.

7. The high-power mid-infrared parametric oscillation amplifier directly pumped by a Tm-doped laser according to claim 5 or 6, characterized in that, The ZGP optical parametric amplifier includes a second ZGP crystal. The ZGP optical parametric amplifier and the ZGP optical parametric oscillator use the same Tm:YLF pump laser. The mid-infrared laser output from the ZGP optical parametric oscillator is coupled to the 1.908μm fundamental frequency light after being split by the Tm:YLF slab amplifier and then coupled to the second ZGP crystal.

8. The high-power mid-infrared parametric oscillation amplifier directly pumped by a Tm-doped laser according to claim 1, characterized in that, The fundamental frequency optical coupling isolation system comprises an isolation component and a fundamental frequency optical spot coupling component. The isolation component includes an isolator, a waveplate, a polarizer, and an absorption cell. The fundamental frequency optical spot coupling component is composed of spherical lenses and cylindrical lenses with different focal lengths. The isolator isolates the 1.908μm fundamental frequency light.

9. The high-power mid-infrared optical parametric oscillation amplification device directly pumped by a Tm-doped laser according to claim 8, characterized in that, The mid-infrared laser coupling isolation system comprises a mid-infrared isolation component and a mid-infrared laser spot coupling component. The isolation component includes an isolator, a waveplate, a polarizer, and an absorption cell. The spot coupling component is composed of spherical lenses with different focal lengths. The isolator isolates the mid-infrared laser.

10. The high-power mid-infrared parametric oscillation amplification device directly pumped by a Tm-doped laser according to claim 1, characterized in that, The Tm:YLF slab amplifier and the ZGP optical parametric amplifier adopt a multi-stage amplification structure. A fundamental frequency optical coupling isolation system is provided between adjacent Tm:YLF slab amplifier stages, and a mid-infrared laser coupling isolation system is provided between adjacent ZGP optical parametric amplifier stages.

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