Deep ultraviolet solid laser based on potassium lithium sulfate crystal

Abstract

The invention provides a deep ultraviolet solid-state laser based on a lithium potassium sulfate crystal. The deep ultraviolet solid-state laser sequentially comprises an ultraviolet laser pumping source, a beam shaping system and a vacuum cavity along a first direction, an incident window sheet, a lithium potassium sulfate (LiKSO4, LPS) deep ultraviolet frequency doubling device, a light splitting prism, a light beam terminator and an emergent window sheet are sequentially arranged in the vacuum cavity along a first direction; wherein ultraviolet laser emitted by the ultraviolet laser pumping source passes through the beam shaping system and then enters the vacuum cavity through the incidence window sheet; in the vacuum cavity, ultraviolet laser is emitted to the lithium potassium sulfate deep ultraviolet frequency doubling device through the incidence window sheet to generate ultraviolet laser and deep ultraviolet frequency doubling laser, the ultraviolet laser and the deep ultraviolet frequency doubling laser are separated after passing through the light splitting prism, the ultraviolet laser is collected by the light beam terminator, and the deep ultraviolet frequency doubling laser is emitted through the emission window sheet.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and in particular to a deep ultraviolet solid-state laser based on lithium potassium sulfate crystals. Background Art

[0002] Deep ultraviolet lasers have advantages such as high photon energy, small thermal effect zone, and high processing precision. They are widely used in laser processing, spectral information, and other fields. Therefore, the development of high-power, stable deep ultraviolet laser sources is urgent.

[0003] Compared to commonly used gas-based UV excimer lasers, solid-state lasers have gained widespread application in industry, scientific research, and other fields due to their reasonable price, high flux, and compact size. Nonlinear optical crystal materials, as key components in laser frequency conversion and optoelectronics, are key components for generating deep-ultraviolet coherent light sources. Currently, only a few deep-ultraviolet nonlinear optical crystals, such as potassium fluoroboryl beryllium oxide crystals, can achieve output below 177nm. However, these crystals face challenges in growth, device complexity, and toxicity, severely hindering their widespread application. Summary of the Invention

[0004] (1) Technical issues to be resolved

[0005] In response to the above-mentioned shortcomings, the main purpose of the present invention is to provide a deep ultraviolet solid-state laser based on lithium potassium sulfate crystal. The laser uses a precisely machined x-cut lithium potassium sulfate crystal as a nonlinear frequency-doubling medium, combined with a 326nm~532nm pulsed pump light source, to successfully achieve deep ultraviolet frequency-doubled laser output in the 163nm~266nm band without the need for periodic poling treatment.

[0006] (2) Technical solution

[0007] To achieve the above-mentioned object, the present invention provides a deep ultraviolet solid-state laser based on lithium potassium sulfate crystal, comprising: an ultraviolet laser pump source, a beam shaping system, and a vacuum cavity; the vacuum cavity comprises: an incident window, a lithium potassium sulfate (LiKSO4, LPS) deep ultraviolet frequency-doubling device, a beam splitter prism, a beam terminator, and an exit window in sequence along a first direction; wherein, ultraviolet laser light emitted by the ultraviolet laser pump source passes through the beam shaping system and then enters the vacuum cavity through the incident window; within the vacuum cavity, the ultraviolet laser light enters the lithium potassium sulfate deep ultraviolet frequency-doubling device through the incident window to generate ultraviolet laser light and deep ultraviolet frequency-doubling laser light, the ultraviolet laser light and the deep ultraviolet frequency-doubling laser light are separated after passing through the beam splitter prism, the ultraviolet laser light is collected by the beam terminator, and the deep ultraviolet frequency-doubling laser light is emitted through the exit window.

[0008] In the above scheme, the ultraviolet laser pump source includes an ultraviolet laser with a wavelength range of 355nm~410nm; wherein, the ultraviolet laser is obtained by a Ti sapphire laser with a wavelength range of 640nm~950nm through a multi-stage frequency converter; or the ultraviolet laser is obtained by a Yb laser with a wavelength range of 1030nm~1080nm through a multi-stage frequency converter; or the ultraviolet laser is obtained by a Nd laser with a wavelength of 1064nm through a multi-stage frequency converter.

[0009] In the above scheme, the lithium potassium sulfate deep ultraviolet frequency doubling device includes an x-cut lithium potassium sulfate crystal with a length range of 1mm to 100mm; the light transmission direction of the lithium potassium sulfate deep ultraviolet frequency doubling device is the non-critical direction required for ultraviolet laser frequency doubling to a deep ultraviolet band with a wavelength range of 163nm to 266nm; the lithium potassium sulfate deep ultraviolet frequency doubling device can achieve random quasi-phase matching frequency doubling based on the ferroelectric domain structure spontaneously formed in the lithium potassium sulfate crystal.

[0010] In the above scheme, the lithium potassium sulfate crystal can achieve deep ultraviolet frequency-doubled laser output with a wavelength of 177nm under ultraviolet laser pumping with a wavelength of 355nm.

[0011] In the above scheme, the nonlinear response of potassium lithium sulfate crystal is determined by the main quantity d 33 Dominant; the polarization direction of the ultraviolet laser emitted by the ultraviolet laser pump source and the polarization direction of the deep ultraviolet frequency-doubled laser are both along the z-axis, and the z-axis is the six-fold symmetry Z-axis of the lithium potassium sulfate crystal.

[0012] In the above scheme, the lithium potassium sulfate crystal does not need periodic polarization treatment, and the lithium potassium sulfate crystal is arranged along the z axis through the needle-shaped ferroelectric domain inside the crystal. 2 non-periodic modulation to achieve random quasi-phase matching frequency doubling.

[0013] In the above scheme, the beam shaping system includes a spherical lens, an aspheric lens, a cylindrical lens and a reflector; the beam shaping system is used to match the ultraviolet laser with the x-ray diffraction pattern in the lithium potassium sulfate crystal. 2 Spatial coupling characteristics of the modulation structure.

[0014] In the above solution, the material of the beam splitter prism includes a deep ultraviolet transparent material; the beam splitter prism is set to the Brewster angle direction to separate the ultraviolet laser and the deep ultraviolet frequency-doubled laser.

[0015] In the above scheme, the environment in the vacuum chamber is 10 -3 Pa vacuum; or the vacuum chamber contains pure nitrogen and helium.

[0016] In the above solution, the materials of the incident window and the exit window both include CaF2, MgF2 and quartz.

[0017] (3) Beneficial effects

[0018] The technical solution of the embodiment of the present invention has at least the following beneficial effects:

[0019] (1) This deep ultraviolet solid-state laser based on lithium potassium sulfate crystal uses a precisely machined x-cut lithium potassium sulfate crystal as a nonlinear frequency-doubled medium, and is combined with a 326nm~532nm pulsed pump light source to successfully achieve deep ultraviolet frequency-doubled laser output in the 163nm~266nm band without the need for periodic polarization treatment.

[0020] (2) The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal has the advantages of low crystal growth cost and compact and small size of laser device.

[0021] (3) This deep ultraviolet solid-state laser based on lithium potassium sulfate crystal uses a CaF2 beam splitter to efficiently separate the ultraviolet pump light from the target wavelength frequency-doubled output. A vacuum or inert gas cavity is also configured to ensure the transmission stability of short-wavelength light. The entire structure is compact, with high energy output, high efficiency, and good engineering feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0024] Figure 1 A schematic structural diagram of a deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to an embodiment of the present invention is shown.

[0025] Please refer to Figure 1 An embodiment of the present invention provides a deep ultraviolet solid-state laser based on lithium potassium sulfate crystal, which includes, in sequence along a first direction X1: an ultraviolet laser pump source 1, a beam shaping system 4, and a vacuum cavity 5; inside the vacuum cavity 5, in sequence along the first direction X1: an incident window 6, a lithium potassium sulfate (LiKSO4, LPS) deep ultraviolet frequency doubling device 2, a beam splitting prism 3, a beam terminator 8, and an exit window 7.

[0026] In an embodiment of the present invention, the deep ultraviolet solid-state laser based on lithium potassium sulfate crystal mainly outputs deep ultraviolet frequency-doubled laser in the wavelength range of 163nm to 266nm.

[0027] The process of deep ultraviolet frequency-doubled laser output of the laser includes: the ultraviolet laser emitted by the ultraviolet laser pump source 1 passes through the beam shaping system 4 and then enters the vacuum cavity 5 through the incident window 6; in the vacuum cavity 5, the ultraviolet laser is incident on the lithium potassium sulfate deep ultraviolet frequency-doubled device 2 through the incident window 6 to generate ultraviolet laser and deep ultraviolet frequency-doubled laser, the ultraviolet laser and the deep ultraviolet frequency-doubled laser are separated after passing through the spectroscopic prism 3, the ultraviolet laser is collected by the beam terminator 8, and the deep ultraviolet frequency-doubled laser is emitted through the output window 7.

[0028] In an embodiment of the present invention, the ultraviolet laser pump source 1 includes an ultraviolet laser with a wavelength range of 355 nm to 410 nm. The ultraviolet laser can be obtained by passing a Ti sapphire laser with a wavelength range of 640 nm to 950 nm through a multi-stage frequency converter; or by passing a Yb laser with a wavelength range of 1030 nm to 1080 nm through a multi-stage frequency converter; or by passing a Nd laser with a wavelength of 1064 nm through a multi-stage frequency converter.

[0029] For example, a Nd:YAG laser is used as the basic light source, and a triple frequency conversion module is used to generate ultraviolet laser with a wavelength of 355nm, wherein the pulse width is about 5ns, the repetition frequency is 10Hz, and the output pulse energy is not less than 2.8mJ.

[0030] In an embodiment of the present invention, a lithium potassium sulfate deep ultraviolet frequency-doubling device 2 comprises x-cut lithium potassium sulfate crystals with a length ranging from 1 mm to 100 mm, the lithium potassium sulfate crystals being crystallized in the hexagonal P63 space group. The light transmission direction of the lithium potassium sulfate deep ultraviolet frequency-doubling device 2 is the non-critical direction required for frequency-doubling ultraviolet lasers to a deep ultraviolet wavelength range of 163 nm to 266 nm. The lithium potassium sulfate deep ultraviolet frequency-doubling device 2 is capable of achieving random quasi-phase-matched frequency doubling based on the ferroelectric domain structure spontaneously formed in the lithium potassium sulfate crystals.

[0031] Furthermore, the nonlinear response of potassium lithium sulfate crystal is determined by the quantity d 33 Dominant; the polarization direction of the ultraviolet laser emitted by the ultraviolet laser pump source 1 and the polarization direction of the deep ultraviolet frequency-doubled laser are both along the z-axis, and the z-axis is the six-fold symmetry axis of the lithium potassium sulfate crystal.

[0032] Furthermore, the lithium potassium sulfate crystal does not need periodic poling treatment, and the lithium potassium sulfate crystal is arranged along the z axis by the needle-shaped ferroelectric domain inside the crystal. 2 non-periodic modulation to achieve random quasi-phase matching frequency doubling.

[0033] In the embodiment of the present invention, the beam shaping system 4 may be composed of a spherical lens, an aspherical lens or a cylindrical lens, a reflector, and the like.

[0034] The beam shaping system 4 is used to match the ultraviolet laser with the x-ray diffraction pattern in the lithium potassium sulfate crystal. 2 Spatial coupling characteristics of the modulation structure.

[0035] Based on the above embodiment, it can be understood that when the ultraviolet laser emitted by the ultraviolet laser pump source 1 passes through the beam shaping system 4, the beam shaping system 4 will make the spatial intensity distribution of the beam match the lithium potassium sulfate deep ultraviolet frequency doubling device 2, that is, the x in the lithium potassium sulfate crystal. 2 The spatial coupling characteristics of the modulation structure are matched.

[0036] Furthermore, after passing through the beam shaping system 4, the ultraviolet laser is incident on the vacuum chamber 5 through the incident window 6. The ultraviolet laser is then incident on the lithium potassium sulfate deep ultraviolet frequency-doubling device 2 through the incident window 6. The lithium potassium sulfate deep ultraviolet frequency-doubling device 2 is arranged in the light-transmitting direction of the phase matching angle. The ultraviolet laser is frequency-doubled in the lithium potassium sulfate deep ultraviolet frequency-doubling device 2 to produce deep ultraviolet frequency-doubled laser light. For example, when pumped by an ultraviolet laser with a wavelength of 355 nm, the lithium potassium sulfate crystal in the lithium potassium sulfate deep ultraviolet frequency-doubling device 2 can achieve a deep ultraviolet frequency-doubled laser output with a wavelength of 177 nm, an output pulse energy of 3.1 μJ, and a conversion efficiency of 0.11%.

[0037] In the embodiment of the present invention, the vacuum cavity 5 is a sealed cavity, and the environment of the vacuum cavity is in a vacuum state. For example, the environment in the vacuum cavity 5 can be evacuated to 10 -3 For another example, the vacuum cavity 5 may also be filled with high-purity nitrogen or helium. The vacuum cavity 5 is used to prevent the deep ultraviolet frequency-doubled laser from losing energy due to air absorption during propagation.

[0038] Based on the above embodiment, due to dispersion reasons, the remaining ultraviolet laser and deep ultraviolet frequency-doubled laser generated by the ultraviolet laser after passing through the lithium potassium sulfate deep ultraviolet frequency-doubled device 2 will be separated after passing through the spectroscopic prism 3.

[0039] In an embodiment of the present invention, the material of the beam splitting prism 3 includes a deep ultraviolet transparent material; the beam splitting prism 3 is arranged at the Brewster angle to separate the ultraviolet laser and the deep ultraviolet frequency-doubled laser.

[0040] Exemplarily, the material of the spectroscopic prism 3 can be CaF2. When the spectroscopic prism 3 is installed at the Brewster angle of deep ultraviolet doubled frequency light, it has low-loss and high-efficiency beam separation performance, thereby being able to separate the ultraviolet fundamental frequency light and the doubled frequency output of deep ultraviolet laser with a wavelength range of 163nm~266nm.

[0041] Based on the above embodiment, after the ultraviolet laser and the deep ultraviolet frequency-doubled laser are separated by the beam splitting prism 3 , the ultraviolet laser is collected by the beam terminator 8 and the deep ultraviolet frequency-doubled laser is emitted through the output window 7 .

[0042] In an embodiment of the present invention, the material of the incident window 6 may be CaF2, MgF2 or quartz, and the material of the exit window 7 may also be CaF2, MgF2 or quartz.

[0043] According to the above-mentioned deep ultraviolet solid laser based on lithium potassium sulfate crystal, Nd:YAG laser is used to output fundamental frequency ultraviolet laser through triple frequency conversion module, and the ultraviolet laser is focused after being shaped by the reflector and lens of beam shaping system 4, and then injected into the lithium potassium sulfate crystal in the lithium potassium sulfate deep ultraviolet frequency doubling device 2 in vacuum cavity 5, and excites the x-ray diffraction inside the lithium potassium sulfate crystal. 2 The modulation structure achieves random quasi-phase-matched frequency-doubled output within the 163nm to 266nm wavelength range without the need for periodic poling. After passing through the lithium potassium sulfate deep ultraviolet frequency-doubled device 2, the remaining ultraviolet laser light and the deep ultraviolet frequency-doubled laser light are separated by a CaF2 prism positioned at the Brewster angle. Finally, the ultraviolet laser light is collected by a beam terminator 8, and the deep ultraviolet frequency-doubled laser light is emitted through an output window 7. During laser transmission and emission, the entire frequency conversion process does not require periodic poling or grating modulation, relying on the naturally formed ferroelectric domain structure of the lithium potassium sulfate crystal to achieve stable and efficient deep ultraviolet output.

[0044] Through the embodiments of the present invention, this deep-ultraviolet solid-state laser based on lithium potassium sulfate crystals uses a CaF2 beamsplitter prism to efficiently separate the ultraviolet pump light from the target wavelength frequency-doubled output. A vacuum or inert gas cavity is also configured to ensure the transmission stability of short-wavelength light. The entire structure is compact, with high energy output, high efficiency, and good engineering feasibility.

[0045] The following is an example of how the deep ultraviolet solid-state laser based on lithium potassium sulfate crystal can output deep ultraviolet frequency-doubled lasers in different wavelength bands.

[0046] In an embodiment of the present invention, based on the above-mentioned deep ultraviolet solid laser, a 355nm pump ultraviolet laser is used to drive a lithium potassium sulfate crystal to output a 177nm deep ultraviolet laser.

[0047] For example, a Nd:YAG laser was used as the primary light source, and a tripled frequency conversion module was used to generate ultraviolet pulsed laser light with a wavelength of 355nm (pulse width 5ns, repetition rate 10Hz, single pulse energy approximately 2.8Mj). The ultraviolet laser light was focused by the aspheric lens of the beam shaping system 4 onto an x-cut lithium potassium sulfate crystal (with the optical axis along the z-axis) with a thickness of 1mm to 100mm in the lithium potassium sulfate deep ultraviolet frequency-doubler device 2 within a nitrogen-filled vacuum chamber. The crystal surface was double-sided polished and not periodically polarized. This crystal generated both ultraviolet laser light and deep ultraviolet frequency-doubler laser light. Finally, after separation by a CaF2 Brewster angle prism, the 177nm second harmonic (deep ultraviolet laser) output was successfully detected.

[0048] On the basis of the above embodiments and based on the above deep ultraviolet solid laser, a deep ultraviolet laser output device with temperature control capability can also be obtained.

[0049] For example, a temperature-controlled hot plate is introduced into the lithium potassium sulfate crystal mounting structure, which can adjust the crystal temperature range to 20-200°C, while other structures remain consistent. Under different temperature conditions, the device can continuously achieve 177nm frequency-doubled output under 355nm pumping, with an energy variation range of within ±15% and an output wavelength drift of less than 1nm. The device has temperature control capabilities and is suitable for deep ultraviolet laser systems in complex working conditions or those requiring precise wavelength tuning, expanding the application scenarios of the device of the present invention in engineering applications.

[0050] On the basis of the above embodiment and based on the above deep ultraviolet solid laser, a deep ultraviolet laser output device can also be obtained by using lithium potassium sulfate crystals of different thicknesses.

[0051] For example, in the above embodiment, only the thickness of the lithium potassium sulfate crystals was changed to 4mm, 8mm, 10mm, 12mm and 15mm in sequence. The light transmission direction of all crystals was parallel to the x-axis and optical grade polishing was performed. The device was installed in a sealed vacuum chamber, equipped with a CaF2 beam splitter and placed at the Brewster angle. Lithium potassium sulfate crystals of different thicknesses can achieve 177nm frequency-doubled output, and the output energy shows a linear growth trend with thickness. This structure demonstrates the flexible adaptability of lithium potassium sulfate crystals under different size conditions and is suitable for deep ultraviolet laser design for different system powers and device structures.

[0052] In another embodiment, based on the above-mentioned deep ultraviolet solid laser, multi-band tunable ultraviolet pumping can achieve deep ultraviolet laser output within the wavelength range of 163nm~266nm.

[0053] For example, a 1064nm pulsed laser is output from an Nd:YAG laser, which is frequency-doubled using an LBO crystal to generate a 532nm laser. This is then tuned to output a 700nm to 810nm signal light using a potassium titanyl phosphate optical parametric oscillator. This signal is then frequency-doubled a second time using a barium metaborate crystal to produce a tunable ultraviolet laser within the 325nm to 405nm wavelength range. Furthermore, the ultraviolet laser passes through the aspheric lens of the beam shaping system 4 and is incident on a 4mm to 10mm thick x-cut lithium potassium sulfate crystal in the lithium potassium sulfate deep ultraviolet frequency-doubling device 2 within a nitrogen-filled vacuum chamber.

[0054] This embodiment achieves deep-ultraviolet second-harmonic generation (DUV) at different pump wavelengths by rotating the crystal angle and adjusting the incident wavelength. After the crystal generates UV laser light and DUV frequency-doubled laser light, it is separated by a CaF2 beamsplitter. Clear DUV signals are observed at multiple wavelengths, with the output covering the 163nm to 266nm range, and the energy fluctuates with wavelength.

[0055] In another embodiment, based on the above-mentioned deep ultraviolet solid laser, multi-segment series connection of lithium potassium sulfate crystals is achieved to enhance deep ultraviolet output.

[0056] For example, two x-cut potassium lithium sulfate crystals, each with a 10mm optical path, were connected end-to-end in series, separated by a CaF2 window, with their optical axes aligned. 355nm pulsed light was used as a pump source to illuminate the tandem device, and an energy meter was used to detect the 177nm frequency-doubled signal at the output. The frequency-doubled output energy of this tandem structure was approximately 40% higher than that of a single crystal, significantly enhancing the output signal. This structure effectively extends the effective interaction length, making it suitable for use in multi-stage frequency conversion amplifiers.

[0057] Through the embodiments of the present invention, the deep ultraviolet solid-state laser based on lithium potassium sulfate crystal uses a precisely machined x-cut lithium potassium sulfate crystal as a nonlinear frequency-doubling medium, and is combined with a 326nm~532nm pulsed pump light source to successfully achieve deep ultraviolet frequency-doubled laser output in the 163nm~266nm band without the need for periodic poling treatment.

[0058] The above specific embodiments further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A deep ultraviolet solid-state laser based on lithium potassium sulfate crystal, characterized in that: The system comprises, in order along a first direction: an ultraviolet laser pump source (1), a beam shaping system (4), and a vacuum cavity (5); The vacuum cavity (5) includes, in sequence along a first direction: an incident window (6), a lithium potassium sulfate (LiKSO4, LPS) deep ultraviolet frequency doubling device (2), a beam splitting prism (3), a beam terminator (8), and an exit window (7); The ultraviolet laser light emitted by the ultraviolet laser pump source (1) passes through the beam shaping system (4) and then enters the vacuum cavity (5) through the incident window (6); In the vacuum cavity (5), the ultraviolet laser is incident on the lithium potassium sulfate deep ultraviolet frequency-doubling device (2) through the incident window (6) to generate ultraviolet laser and deep ultraviolet frequency-doubling laser. The ultraviolet laser and deep ultraviolet frequency-doubling laser are separated after passing through the beam splitter prism (3). The ultraviolet laser is collected by the beam terminator (8), and the deep ultraviolet frequency-doubling laser is emitted through the exit window (7).

2. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 1, characterized in that: The ultraviolet laser pump source (1) comprises an ultraviolet laser with a wavelength range of 355 nm to 410 nm; Wherein, the ultraviolet laser is obtained by a Ti sapphire laser with a wavelength range of 640 nm to 950 nm through a multi-stage frequency converter; or The ultraviolet laser is obtained by Yb laser with a wavelength range of 1030 nm to 1080 nm through a multi-stage frequency converter; or The ultraviolet laser is a 1064nm Nd laser obtained through a multi-stage frequency converter.

3. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 1, characterized in that The lithium potassium sulfate deep ultraviolet frequency doubling device (2) comprises an x-cut lithium potassium sulfate crystal with a length ranging from 1 mm to 100 mm, wherein the lithium potassium sulfate crystal is crystallized in the hexagonal system P63 space group; The light transmission direction of the lithium potassium sulfate deep ultraviolet frequency doubling device (2) is the non-critical direction required for frequency doubling the ultraviolet laser to a deep ultraviolet band with a wavelength range of 163nm to 266nm; The lithium potassium sulfate deep ultraviolet frequency doubling device (2) can realize random quasi-phase matching frequency doubling according to the ferroelectric domain structure spontaneously formed by the lithium potassium sulfate crystal.

4. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 3, characterized in that: The lithium potassium sulfate crystal can realize deep ultraviolet frequency-doubled laser output with a wavelength of 177 nm under ultraviolet laser pumping with a wavelength of 355 nm.

5. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 3, characterized in that: The nonlinear response of the lithium potassium sulfate crystal is determined by the principle d 33 leading; The polarization direction of the ultraviolet laser emitted by the ultraviolet laser pump source (1) and the polarization direction of the deep ultraviolet frequency-doubled laser are both along the z-axis direction, and the z-axis is the six-fold symmetry axis of the lithium potassium sulfate crystal.

6. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 3 or 5, characterized in that: The lithium potassium sulfate crystal does not need periodic polarization treatment, and the lithium potassium sulfate crystal is arranged along the z axis by the needle-shaped ferroelectric domain inside the crystal. 2 non-periodic modulation to achieve random quasi-phase matching frequency doubling.

7. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 6, characterized in that: The beam shaping system (4) includes a spherical lens, an aspherical lens, a cylindrical lens and a reflector; The beam shaping system (4) is used to match the ultraviolet laser with the x in the lithium potassium sulfate crystal. 2 Spatial coupling characteristics of the modulation structure.

8. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 1, characterized in that: The material of the beam splitting prism (3) includes a deep ultraviolet transparent material; The beam splitting prism (3) is set in the Brewster angle direction to separate the ultraviolet laser and the deep ultraviolet frequency-doubled laser.

9. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 1, characterized in that: The environment in the vacuum chamber (5) is 10 -3 Pa vacuum; or The vacuum chamber (5) contains pure nitrogen and helium.

10. The deep ultraviolet solid-state laser based on lithium potassium sulfate crystal according to claim 1, characterized in that: The materials of the incident window (6) and the exit window (7) both include CaF2, MgF2 and quartz.

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