Multi-wavelength output nanosecond laser

Abstract

The invention relates to the technical field of lasers, in particular to a multi-wavelength output nanosecond laser. The laser comprises a pumping source, a pumping coupling device, a pumping end mirror, a gain crystal, a Q-switching device, a turning mirror, a frequency tripling crystal, a frequency doubling crystal and a tail end mirror. A pumping source, a pumping coupling device, a pumping end mirror, a gain crystal, a Q-switching device and a turning mirror are sequentially arranged in the light emitting direction of the pumping source. A turning mirror, a frequency tripling crystal, a frequency doubling crystal and a tail end mirror are sequentially arranged along the reflection direction of the turning mirror; the tail end mirror is a plane mirror, the end face, facing the frequency doubling crystal, of the tail end mirror is plated with a fundamental frequency light partial reflection film and a frequency doubling light high reflection film, and the transmittance of the fundamental frequency light partial reflection film is 2%-98%. The multi-wavelength output nanosecond laser provided by the invention can synchronously output multi-wavelength nanosecond laser with adjustable power pulse width by controlling the transmittance of the film layer of the output lens at the tail end.

Description

Technical Field

[0001] This application relates to the field of laser technology, and more particularly to a nanosecond laser with multi-wavelength output. Background Technology

[0002] In recent years, solid-state nanosecond lasers have been widely used in industrial processing, medical aesthetics, spectral analysis, lidar (LiDAR), and scientific research due to their advantages such as compact structure, high stability, long lifespan, and high output power. However, traditional solid-state nanosecond lasers typically only output a single wavelength or rely on nonlinear optical crystals (such as KTP, BBO, and LBO) for frequency doubling, sum-frequency conversion, or difference-frequency conversion to achieve limited wavelength extension. This approach not only increases the complexity of the optical system but may also lead to reduced conversion efficiency, deteriorated beam quality, and decreased system stability.

[0003] In the existing technology, the realization of multi-wavelength laser output mainly relies on the following schemes: (1) Multi-laser combination: multiple independent lasers are used to output different wavelengths, and then an optical beam combiner is used to realize multi-wavelength output. This scheme is bulky, expensive, and difficult to synchronize between wavelengths. (2) Tunable laser: wavelength tuning is realized based on dye lasers or optical parametric oscillators (OPOs), but such systems have complex structures, high maintenance costs, and are difficult to output multiple fixed wavelengths at the same time.

[0004] Furthermore, traditional solid-state lasers often face problems such as thermal lensing and insufficient uniformity of the gain medium when operating with nanosecond pulses, further limiting the stability and efficiency of multi-wavelength output. It is evident that existing technologies for multi-wavelength nanosecond laser output still suffer from drawbacks such as system complexity, low efficiency, high cost, or insufficient stability. Therefore, there is an urgent need for a compact, highly efficient, and stable solid-state laser capable of simultaneously outputting multi-wavelength nanosecond pulses to meet the growing demands of multispectral applications. Summary of the Invention

[0005] The technical problem to be solved by this application is to solve at least one of the technical problems mentioned above.

[0006] The solution to the technical problem in this application is: This application provides a multi-wavelength output nanosecond laser, which includes a pump source, a pump coupling device, a pump end mirror, a gain crystal, a Q-switching device, a transition mirror, a third-harmonic crystal, a second-harmonic crystal, and a tail end mirror. The pump source, the pump coupling device, the pump end mirror, the gain crystal, the Q-switching device, and the transition mirror are arranged sequentially along the light emission direction of the pump source. The conversion mirror, the third harmonic crystal, the second harmonic crystal, and the tail end mirror are arranged sequentially along the reflection direction of the conversion mirror. The tail end mirror is a plane mirror, and the end face of the tail end mirror facing the second harmonic crystal is coated with a fundamental frequency light partial reflective film and a second harmonic light high reflective film. The transmittance of the fundamental frequency light partial reflective film is 2%-98%.

[0007] As a further improvement to the above technical solution, the pump coupling device is provided with a lens group, all of which are coated with a high-transmittance film for pump light, for shaping the pump light.

[0008] As a further improvement to the above technical solution, the pump end mirror is a plano-convex lens, a plano-concave lens, or a plane mirror; The end face of the pump end mirror facing the pump source is coated with a pump light transmittance film, and the end face facing away from the pump source is coated with a pump light high transmittance film and a fundamental frequency light high reflectance film.

[0009] As a further improvement to the above technical solution, the gain crystal is coated with a fundamental frequency high-transmittance film and a pump light high-transmittance film. The gain crystal is made of one of the following materials: neodymium yttrium vanadate crystal, neodymium yttrium aluminum garnet crystal, ytterbium yttrium aluminum garnet crystal, neodymium gadolinium vanadate crystal, or neodymium lithium fluoride yttrium crystal.

[0010] As a further improvement to the above technical solution, one end of the third harmonic crystal is cut at Brewster's angle, with a smooth cut surface and an orientation corresponding to the turning mirror. The other end of the third harmonic crystal is a plane facing the second harmonic crystal and is coated with a fundamental frequency high-transmittance film and a second harmonic high-transmittance film.

[0011] As a further improvement to the above technical solution, the material of the third harmonic crystal is one of lithium triborate, potassium titanium oxyphosphate, β-phase barium metaborate crystal, or periodically polarized lithium niobate crystal.

[0012] As a further improvement to the above technical solution, both ends of the second-harmonic crystal are coated with a high-transmittance film for the fundamental frequency and a high-transmittance film for the second-harmonic frequency. The second harmonic crystal is made of one of the following materials: lithium triborate, potassium titanium oxyphosphate, β-phase barium metaborate crystal, or periodically polarized lithium niobate crystal.

[0013] As a further improvement to the above technical solution, the end face of the tail end mirror opposite to the second harmonic crystal is coated with a high-transmittance film for the fundamental frequency.

[0014] The beneficial effect of this application is that, in this application, the pump light generated by the pump source is shaped by the pump coupling device and then passes through the pump end mirror before entering the gain crystal. After the gain crystal absorbs the pump light from the pump source, a large number of low-energy particles jump to high-energy levels, forming population inversion. At this time, the spontaneously radiated fundamental frequency light undergoes stimulated emission amplification when passing through the gain crystal. The initially amplified fundamental frequency light passes through the gain crystal, is reflected by the pump end mirror, and is amplified again by the gain crystal. It is then projected through the Q-switched crystal, reflected by the deflector, and then to the third harmonic crystal. The end face of the third harmonic crystal is cut at Brewster's angle near the deflector. The fundamental frequency light is refracted through this cut surface and passes through the third harmonic crystal. When it enters the second harmonic crystal, a frequency doubling effect is generated, converting the fundamental frequency light into green light. The generated green light and the remaining fundamental frequency light are incident on the tail end mirror, and then... The tail end is coated with a high-reflectivity film for frequency doubling and a partial reflective film for fundamental frequency. The reflectivity can be 1-99%. Part of the fundamental frequency light is directly output as the target laser after passing through the tail end mirror. The remaining fundamental frequency light and frequency doubling light are reflected by the tail end mirror and then injected into the second harmonic crystal. At this time, part of the remaining fundamental frequency light is further converted into frequency doubling light. The generated frequency doubling light and the unconverted fundamental frequency light are injected into the third harmonic crystal to produce a sum-frequency effect and generate third harmonic light. Since the refractive indices of the frequency doubling light, third harmonic light and fundamental frequency light are different at the third harmonic crystal, the exit angles at the cut corner of the third harmonic crystal are also different. The target frequency doubling light and third harmonic light will be output at a predetermined angle, while the remaining unconverted fundamental frequency light will return along the original optical path and continue to be amplified by the gain crystal and then frequency doubling, thereby forming a stable resonant cavity. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the optical path of the multi-wavelength output nanosecond laser of this application.

[0016] Figure 2 This is a power-pulse width-repetition frequency characteristic curve of Embodiment 5 of this application.

[0017] The reference numerals in the attached figures are as follows: 1. Pump source; 2. Pump coupling device; 3. Pump end mirror; 4. Gain crystal; 5. Q-switching device; 6. Conversion mirror; 7. Third harmonic crystal; 8. Second harmonic crystal; 9. Tail end mirror. Detailed Implementation

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments have been briefly explained above. Obviously, the described drawings are only a part of the embodiments of this application, and not all of them. Those skilled in the art can obtain other design schemes and drawings based on these drawings without creative effort.

[0019] The following will clearly and completely describe the concept, specific structure, and resulting technical effects of this application in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of this application. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application. Furthermore, all connections / linkages mentioned herein do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this application can be combined interactively without contradicting each other.

[0020] The purpose of this application is to provide a novel multi-wavelength solid-state nanosecond laser that achieves efficient and stable multi-wavelength synchronous or switchable output by optimizing the gain medium design, resonant cavity structure and wavelength selection mechanism, thereby overcoming the above-mentioned technical bottlenecks.

[0021] Reference Figure 1 This application provides a nanosecond laser with multi-wavelength output, which includes a pump source 1, a pump coupling device 2, a pump end mirror 3, a gain crystal 4, a Q-switching device 5, a transition mirror 6, a third harmonic crystal 7, a second harmonic crystal 8, and a tail end mirror 9. Along the light emission direction of the pump source 1, the pump source 1, the pump coupling device 2, the pump end mirror 3, the gain crystal 4, the Q-switching device 5, and the transition mirror 6 are arranged sequentially. Along the reflection direction of the conversion mirror 6, the third harmonic crystal 7, the second harmonic crystal 8, and the tail end mirror 9 are arranged sequentially. The tail end mirror 9 is a plane mirror. The end face of the tail end mirror 9 facing the second harmonic crystal 8 is coated with a fundamental frequency light partial reflective film and a second harmonic light high reflective film. The transmittance of the fundamental frequency light partial reflective film is 2%-98%.

[0022] Pump source 1 is used to generate pump light, the wavelength of which can be 808nm or 878.6nm, etc. Pump source 1 can be a semiconductor laser.

[0023] In this application, the two-stage optical path design along the light output direction of pump source 1 and the reflection direction of conversion mirror 6 makes the pumping, amplification, and frequency doubling process compact and orderly. After the fundamental frequency light is amplified twice by gain crystal 4, the synchronous generation of fundamental frequency light (e.g., 1064nm), frequency-doubled light (e.g., 532nm), and third-doubled light is achieved through the cascading effect of third-doubled crystal 7 and second-doubled crystal 8. This solves the problems of dispersed structure and difficult optical path coupling in traditional multi-wavelength lasers. The end face of the tail mirror 9 facing the second-doubled crystal 8 is coated with a partial reflective film for fundamental frequency light (transmittance 2%-98%) and a high reflective film for frequency-doubled light. This allows some fundamental frequency light to be directly output and can reflect the remaining fundamental frequency light and frequency-doubled light back to the crystal to continue participating in frequency doubling and summing, which greatly improves the multi-wavelength conversion efficiency. At the same time, in conjunction with the Brewster angle cut of third-doubled crystal 7, the difference in refractive index of different wavelengths of light is used to achieve precise separation and output, ensuring the purity of multi-wavelength lasers.

[0024] Specifically, the pump light generated by pump source 1 is shaped by pump coupling device 2, passes through pump end mirror 3, and then enters gain crystal 4. After absorbing the pump light from pump source 1, a large number of low-energy particles in gain crystal 4 transition to high-energy levels, resulting in population inversion. At this time, the spontaneously emitted fundamental frequency light undergoes stimulated emission amplification when passing through gain crystal 4. The wavelength of this fundamental frequency light is, for example, 1064 nm. The initially amplified fundamental frequency light passes through gain crystal 4, is reflected by pump end mirror 3, and then amplified again by gain crystal 4. It is then projected through Q-switched crystal 5, and then reflected by refraction mirror 6 to third harmonic crystal 7. The end face of third harmonic crystal 7 is cut at Brewster's angle near refraction mirror 6. The fundamental frequency light is refracted through this cut surface and passes through third harmonic crystal 7. When it enters second harmonic crystal 8, it generates a frequency doubling effect, converting the 1064 nm fundamental frequency light into 532 nm green light. The generated green light and the remaining The fundamental frequency light is incident on the tail end mirror 9. Since the tail end is coated with a high-reflectivity film for frequency doubling and a partial reflective film for fundamental frequency light, the reflectivity can be 1-99%. Part of the fundamental frequency light is directly output as the target laser after passing through the tail end mirror 9. The remaining fundamental frequency light and frequency doubling light are reflected by the tail end mirror 9 and then enter the second frequency doubling crystal 8 again. At this time, part of the remaining fundamental frequency light is further converted into frequency doubling light. The generated frequency doubling light and the unconverted fundamental frequency light are jointly injected into the third frequency doubling crystal 7 to generate a sum-frequency effect and thus generate third frequency doubling light. At this time, since the refractive indices of the frequency doubling light, third frequency doubling light and fundamental frequency light are different at the third frequency doubling crystal 7, the exit angles at the chamfered corner of the third frequency doubling crystal 7 are also different. The target frequency doubling light and third frequency doubling light will be output at a predetermined angle, while the remaining unconverted fundamental frequency light will return along the original optical path and continue to be amplified by the gain crystal 4 and then frequency doubling, thereby forming a stable resonant cavity.

[0025] In one specific embodiment of this application, the Q-switched crystal 5 is an acousto-optic crystal or an electro-optic crystal.

[0026] In this application, the Q-switched crystal 5 is used to modulate the fundamental frequency light. The modulation of the fundamental frequency light is achieved by controlling the loss of the fundamental frequency light in the cavity. When the Q-switched crystal 5 is working, the fundamental frequency light is deflected out of the cavity after passing through the Q-switched crystal 5, and the number of particles in the upper energy level in the resonant cavity accumulates rapidly. When the Q-switched crystal 5 is suddenly stopped, the number of particles in the cavity is amplified and carried away by the fundamental frequency signal light in a very short time, thereby forming a giant pulse fundamental frequency light with high peak power. This provides a high energy density fundamental frequency light input for the subsequent efficient frequency conversion of the third harmonic crystal 7 and the second harmonic crystal 8.

[0027] In one specific embodiment of this application, the pump coupling device 2 is provided with a lens group, all coated with a high-transmittance film for pump light, for shaping the pump light.

[0028] In this application, the pump coupling device 2 is equipped with a lens group, and each lens in the lens group is coated with a pump light high-transmittance film. This allows the pump coupling device 2 to shape the pump light. By adjusting the lens combination to match the fundamental frequency spot size, the fundamental frequency light is optimally amplified. Specifically, the lens group in the pump coupling device 2 is coated with a pump light high-transmittance film, which reduces transmission loss during the pump light shaping process and ensures that the 808nm or 878.6nm pump light generated by the pump source 1 is efficiently transmitted to the gain crystal 4. By adjusting the lens combination, the fundamental frequency spot size can be precisely matched, so that the pump light and the gain region of the gain crystal 4 fully overlap, achieving the best amplification effect of the fundamental frequency light and providing sufficient fundamental frequency light energy for subsequent multi-wavelength conversion.

[0029] In one specific embodiment of this application, the pump end mirror 3 is a plano-convex lens, a plano-concave lens, or a plane mirror; The pump end mirror 3 has a pump light transmission film deposited on the end face facing the pump source 1, and a pump light high transmission film and a fundamental frequency light high reflectivity film deposited on the end face facing away from the pump source 1.

[0030] In this application, the pump end mirror 3 is selected as a plano-convex lens, plano-concave lens or plane mirror. The end face facing the pump source 1 is coated with a pump light transmission film, and the back end face is coated with a pump light high transmission film and a fundamental frequency light high reflection film. The dual transmission film design ensures that the pump light passes through without loss. The fundamental frequency light high reflection film stably confines the fundamental frequency light in the resonant cavity for secondary amplification, ensuring the stability of the fundamental frequency light amplification, providing a fundamental frequency light with uniform energy and stable phase for multi-wavelength conversion, and avoiding multi-wavelength output power fluctuations caused by the instability of the fundamental frequency light.

[0031] In one specific embodiment of this application, the gain crystal 4 is coated with a fundamental frequency high-transmittance film and a pump light high-transmittance film; The gain crystal 4 is made of one of the following materials: neodymium-doped yttrium vanadate crystal, neodymium-doped yttrium aluminum garnet crystal, ytterbium-doped yttrium aluminum garnet crystal, neodymium-doped gadolinium vanadate crystal, or neodymium-doped lithium fluoride yttrium crystal.

[0032] In this application, the gain crystal 4 is coated with a fundamental frequency light high-transmittance film and a pump light high-transmittance film, which are used to absorb the pump light emitted by the pump and amplify the fundamental frequency light. It can be one of neodymium-doped yttrium vanadate (Nd:YVO4) crystal, neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal, ytterbium-doped yttrium aluminum garnet (Yb:YAG) crystal, neodymium-doped gadolinium vanadate (Nd:GdVO4) crystal or neodymium-doped lithium fluoride yttrium (Nd:YLF) crystal, but is not limited thereto. Specifically, the high-transmittance film for fundamental frequency light and high-transmittance film for pump light coated on the gain crystal 4 reduces optical transmission loss and improves pump absorption and fundamental frequency light amplification efficiency. The high-gain properties of the crystal are matched with the 808nm or 878.6nm pump light absorption peak of the pump source 1, which can efficiently realize population inversion and fundamental frequency light amplification. This is beneficial for providing a sufficient and stable fundamental frequency light energy basis for multi-wavelength laser output. The availability of multiple materials also broadens the power adjustment range of multi-wavelength output.

[0033] In one specific embodiment of this application, one end of the third harmonic crystal 7 is cut at Brewster's angle, with a smooth cut surface and an orientation corresponding to the turning mirror 6. The other end of the third harmonic crystal 7 is a plane facing the second harmonic crystal 8 and is coated with a fundamental frequency high-transmittance film and a second harmonic high-transmittance film.

[0034] In this application, the third-harmonic crystal 7 is cut at Brewster's angle. When the fundamental frequency light is refracted through the third-harmonic crystal 7 and enters the second-harmonic crystal 8, a frequency doubling effect is generated, converting the fundamental frequency light into the target output green light. The generated green light and the remaining fundamental frequency light are then incident on the tail end mirror 9. Specifically, one end of the third-harmonic crystal 7 is cut at Brewster's angle with a smooth cut surface, corresponding to the direction of the turning mirror 6. The other end is coated with a high-transmittance film for the fundamental frequency light and a high-transmittance film for the frequency doubling light. The Brewster's angle cut surface utilizes the difference in refractive index of different wavelengths of light to achieve precise separation of the frequency doubling light, the third-harmonic light, and the fundamental frequency light, avoiding mutual interference when multiple wavelengths are output. At the same time, no additional separation components are needed, reducing light loss. The high-transmittance film for the fundamental frequency light and the high-transmittance film for the frequency doubling light can ensure smooth transmission of the fundamental frequency light and the frequency doubling light, improving the sum-frequency effect efficiency. In one specific embodiment of this application, the material of the third harmonic crystal 7 may be one of lithium triborate (LiB3O5, LBO), potassium titanium oxyphosphate (KTiOPO4, KTP), β-phase barium metaborate (β-BaB2O4, BBO), or periodically polarized lithium niobate (PPLN), but is not limited thereto.

[0035] In this application, the selected crystal possesses excellent nonlinear optical properties, is adapted to the efficient frequency conversion of nanosecond pulses, and provides a guarantee for the stable generation of multi-wavelength lasers.

[0036] In one specific embodiment of this application, the end faces of both ends of the second-harmonic crystal 8 are coated with a fundamental frequency high-transmittance film and a second-harmonic high-transmittance film. The second harmonic crystal 8 is made of one of the following materials: lithium triborate, potassium titanium oxyphosphate, β-phase barium metaborate crystal, or periodically polarized lithium niobate crystal.

[0037] In this application, the second-harmonic crystal 8 primarily generates a frequency-doubling effect on the transmitted fundamental frequency light, converting it to a suitable wavelength for output. Its two end faces are coated with a high-transmittance film for the fundamental frequency and a high-transmittance film for the frequency-doubling, reducing light transmission loss and ensuring efficient conversion of the fundamental frequency light into the frequency-doubled light. Simultaneously, it ensures the smooth transmission of the frequency-doubled light to the third-harmonic crystal 7 for frequency multiplication. The selected materials, such as lithium triborate, form a cascaded frequency-doubling structure with the third-harmonic crystal 7. This crystal cascading improves frequency conversion efficiency and overcomes the shortcomings of insufficient conversion in traditional single-harmonic crystals. Combined with a temperature adjustment function, the conversion efficiency of different wavelengths can be optimized, ensuring the balance and stability of power across wavelengths during multi-wavelength output, meeting the power ratio requirements of various scenarios.

[0038] Specifically, this application can also adjust the temperature of the third harmonic crystal 7 and the second harmonic crystal 8 to obtain the maximum power for each output wavelength.

[0039] In one specific embodiment of this application, the end face of the tail mirror 9 opposite to the second harmonic crystal 8 is coated with a high-transmittance film for the fundamental frequency.

[0040] In this application, the end face of the tail mirror 9 opposite to the frequency-doubled crystal 8 is coated with a high-transmittance film for the fundamental frequency light, further reducing the loss during fundamental frequency light output and ensuring that the directly output fundamental frequency light has sufficient power. Combined with the partial reflective film for the fundamental frequency light and the high-reflective film for the frequency-doubled light on the end face facing the frequency-doubled crystal 8, a "output-reflection-reconversion" cycle is formed, which not only ensures the synchronous output of multiple wavelengths but also improves the utilization rate of the fundamental frequency light. This film system design allows the tail mirror 9 to simultaneously serve as an output window and a reflector, simplifying the multi-wavelength output structure and ensuring the output stability and purity of each wavelength of laser.

[0041] The following specific examples provide further details.

[0042] Example 1: UV standalone output instance The multi-wavelength output nanosecond laser of Example 1 includes a pump source 1, a pump coupling device 2, a pump end mirror 3, a gain crystal 4, a Q-switching device 5, a transition mirror 6, a third harmonic crystal 7, a second harmonic crystal 8, and a tail end mirror 9. Along the light emission direction of pump source 1, pump source 1, pump coupling device 2, pump end mirror 3, gain crystal 4, Q-switching device 5 and deflection mirror 6 are arranged in sequence; along the reflection direction of deflection mirror 6, deflection mirror 6, third harmonic crystal 7, second harmonic crystal 8 and tail end mirror 9 are arranged in sequence.

[0043] Among them, pump source 1: a semiconductor laser with a wavelength of 808nm; pump coupling device 2: the inner lens group is coated with an 808nm pump light high-transmittance film (transmittance ≥99%); pump end mirror 3: a plano-convex lens, the end face facing pump source 1 is coated with an 808nm pump light high-transmittance film (transmittance ≥99%), and the end face facing away is coated with an 808nm pump light high-transmittance film (transmittance ≥99%) + a 1064nm fundamental frequency high-reflection film (reflectance ≥99%). 99.8%); Gain Crystal 4: Nd:YVO4 crystal, with 808nm pump light high-transmittance film (transmittance ≥99%) + 1064nm fundamental frequency light high-transmittance film (transmittance ≥99.8%) deposited on both ends; Q-switching device 5: acousto-optic Q crystal, with 1064nm fundamental frequency light high-transmittance film (transmittance ≥99.8%) deposited on the light-transmitting surface; Conversion Mirror 6: plane mirror, with 1064nm fundamental frequency light high-reflectance film (reflectivity ≥99%). 8%); Third harmonic crystal 7: LBO crystal, with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm second harmonic frequency high-transmittance film (transmittance ≥99.8%) deposited on the Brewster corner facet, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm second harmonic frequency high-transmittance film (transmittance ≥99.8%) deposited on both flat ends; Second harmonic crystal 8: LBO crystal, with 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on both ends. 1064nm fundamental frequency high-transmittance film (transmittance ≥ 99.8%) + 532nm second-order frequency high-transmittance film (transmittance ≥ 99.8%); Tail end mirror 9: Plane reflecting mirror, with a 1064nm fundamental frequency partial reflective film (transmittance 0%-2%) + 532nm second-order frequency high reflective film (reflectance ≥ 99.8%) deposited on the end face facing away from the crystal 8, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥ 99.8%).

[0044] The transmittance of the fundamental frequency light reflective film of the tail end mirror 9 is set to 0%-2%, the transmittance of the second-harmonic light is 0%-2%, the temperature of the second-harmonic crystal 8 is controlled at 45℃, the temperature of the third-harmonic crystal 7 is controlled at 45℃, and the appropriate wavelength of the pump light is adjusted so that the ultraviolet light is output from the Brewster angle section of the third-harmonic crystal 7. At this time, the ultraviolet power can be output from 0.1-30W.

[0045] Example 2: Green Light Output Example The multi-wavelength output nanosecond laser of Example 2 includes a pump source 1, a pump coupling device 2, a pump end mirror 3, a gain crystal 4, a Q-switching device 5, a transition mirror 6, a third harmonic crystal 7, a second harmonic crystal 8, and a tail end mirror 9. Along the light emission direction of pump source 1, pump source 1, pump coupling device 2, pump end mirror 3, gain crystal 4, Q-switching device 5 and deflection mirror 6 are arranged in sequence; along the reflection direction of deflection mirror 6, deflection mirror 6, third harmonic crystal 7, second harmonic crystal 8 and tail end mirror 9 are arranged in sequence.

[0046] Among them, pump source 1 is a semiconductor laser with a wavelength of 878.6nm; pump coupling device 2 consists of inner lens groups, each coated with an 878.6nm pump light high-transmittance film (transmittance ≥99%); pump end mirror 3 is a plano-concave lens, with the end face facing pump source 1 coated with an 878.6nm pump light high-transmittance film (transmittance ≥99%) and the end face facing away coated with an 878.6nm pump light high-transmittance film (transmittance ≥99%) + 1064nm fundamental frequency high reflectance film. Film (reflectivity ≥ 99.8%); Gain Crystal 4: Nd:YAG crystal, with both ends coated with an 878.6nm pump light high-transmittance film (transmittance ≥ 99%) + a 1064nm fundamental frequency high-transmittance film (transmittance ≥ 99.8%); Q-switching Device 5: Electro-optic Q-switching crystal, with a 1064nm fundamental frequency high-transmittance film (transmittance ≥ 99.8%) on the light-transmitting surface; Conversion Mirror 6: Plane mirror, coated with a 1064nm fundamental frequency high-reflectance film (reflectivity ≥ 99.8%). Frequency harmonics ≥ 99.8%); Third harmonic crystal 7: BBO crystal, with a 1064nm fundamental frequency high-transmittance film (transmittance ≥ 99.8%) + a 532nm frequency harmonic high-transmittance film (transmittance ≥ 99.8%) deposited on the Brewster corner facet, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥ 99.8%) + a 532nm frequency harmonic high-transmittance film (transmittance ≥ 99.8%) deposited on the flat end; Second harmonic crystal 8: BBO crystal, with 1... 064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%); Tail end mirror 9: Plane reflecting mirror, with a 1064nm fundamental frequency partial reflective film (transmittance 0%-2%) + 532nm frequency-doubled high reflective film (reflectance ≥99.8%) deposited on the end face facing away from the crystal 8, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on the end face facing away from the crystal 8.

[0047] The transmittance of the fundamental frequency light reflector film of the tail end mirror 9 is set to 0%-2%, the transmittance of the second frequency light is 0%-2%, the temperature of the second frequency crystal 8 is controlled at 45℃, and the temperature of the third frequency crystal 7 is controlled at 30℃. The appropriate wavelength of the pump light is adjusted so that the green light is output from the Brewster angle cut surface of the third frequency crystal 7. At this time, the green light power can be output from 0.1-40W.

[0048] Example 3: Infrared standalone output example: The multi-wavelength output nanosecond laser of Example 3 includes a pump source 1, a pump coupling device 2, a pump end mirror 3, a gain crystal 4, a Q-switching device 5, a transition mirror 6, a third harmonic crystal 7, a second harmonic crystal 8, and a tail end mirror 9. Along the light emission direction of pump source 1, pump source 1, pump coupling device 2, pump end mirror 3, gain crystal 4, Q-switching device 5 and deflection mirror 6 are arranged in sequence; along the reflection direction of deflection mirror 6, deflection mirror 6, third harmonic crystal 7, second harmonic crystal 8 and tail end mirror 9 are arranged in sequence.

[0049] The system comprises: Pump source 1: an 808nm semiconductor laser; Pump coupling device 2: an inner lens group coated with an 808nm pump light high-transmittance film (transmittance ≥99%); Pump end mirror 3: a plane mirror, with an 808nm pump light high-transmittance film (transmittance ≥99%) on the end face facing pump source 1 and an 808nm pump light high-transmittance film (transmittance ≥99%) + a 1064nm fundamental frequency high-reflectance film (reflectance ≥99.8%) on the back end face; Gain crystal 4: a Yb:YAG crystal, with both end faces coated with an 808nm pump light high-transmittance film (transmittance ≥99%) + a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%); Q-switching device 5: an acousto-optic Q-crystal, with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) on the light-transmitting surface; and a deflector 6: a plane mirror coated with a 1064nm fundamental frequency high-reflectance film (reflectance ≥99%). 0.8%); Third harmonic crystal 7: KTP crystal, with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm second harmonic frequency high-transmittance film (transmittance ≥99.8%) deposited on the Brewster corner facet, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm second harmonic frequency high-transmittance film (transmittance ≥99.8%) deposited on both flat ends; Second harmonic crystal 8: KTP crystal, with 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on both ends. 64nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%); Tail end mirror 9: Plane reflecting mirror, with a 1064nm fundamental frequency partial reflective film (transmittance 15%) + 532nm frequency-doubled high reflective film (reflectance ≥99.8%) deposited on the end face facing away from the crystal 8, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on the end face facing away from the crystal 8.

[0050] The transmittance of the fundamental frequency light reflector film of the tail end mirror 9 is set to 15%, the transmittance of the second frequency light is 0%-2%, the temperature of the second frequency crystal 8 is controlled at 30℃, the temperature of the third frequency crystal 7 is controlled at 30℃, and the appropriate wavelength of the pump light is adjusted so that the infrared light is output from the Brewster angle section of the third frequency crystal 7. At this time, the infrared power output can be 0.1-60W.

[0051] Example 4: Simultaneous Output of Infrared and Green Light The multi-wavelength output nanosecond laser of Example 4 includes a pump source 1, a pump coupling device 2, a pump end mirror 3, a gain crystal 4, a Q-switching device 5, a transition mirror 6, a third harmonic crystal 7, a second harmonic crystal 8, and a tail end mirror 9. Along the light emission direction of pump source 1, pump source 1, pump coupling device 2, pump end mirror 3, gain crystal 4, Q-switching device 5 and deflection mirror 6 are arranged in sequence; along the reflection direction of deflection mirror 6, deflection mirror 6, third harmonic crystal 7, second harmonic crystal 8 and tail end mirror 9 are arranged in sequence.

[0052] Among them, pump source 1: a semiconductor laser with a wavelength of 808nm; pump coupling device 2: the inner lens group is coated with an 808nm pump light high-transmittance film (transmittance ≥99%); pump end mirror 3: a plano-convex lens, the end face facing pump source 1 is coated with an 808nm pump light high-transmittance film (transmittance ≥99%), and the end face facing away is coated with an 808nm pump light high-transmittance film (transmittance ≥99%) + a 1064nm fundamental frequency high-reflection film (reflectance ≥99%). 99.8%); Gain Crystal 4: Nd:GdVO4 crystal, with 808nm pump light high-transmittance film (transmittance ≥99%) + 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on both ends; Q-switching device 5: Electro-optic Q-switching crystal, with 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on the light-transmitting surface; Conversion Mirror 6: Plane mirror, with 1064nm fundamental frequency high-reflectance film (reflectance ≥99%). 0.8%); Third-harmonic crystal 7: PPLN crystal, with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%) deposited on the Brewster corner facet, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%) deposited on the flat end; Second-harmonic crystal 8: PPLN crystal, with 1... 064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%); Tail end mirror 9: Plane reflecting mirror, with a 1064nm fundamental frequency partial reflective film (transmittance 15%) + 532nm frequency-doubled high reflective film (reflectance ≥99.8%) deposited on the end face facing away from the crystal 8, and a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on the end face facing away from the crystal 8.

[0053] The transmittance of the fundamental frequency reflective film of the tail end mirror 9 is set to 15%, the transmittance of the frequency-doubled light is 0%-2%, the temperature of the second-harmonic crystal 8 is controlled at 45℃, and the temperature of the third-harmonic crystal 7 is controlled at 30℃. The appropriate wavelength of the pump light is adjusted so that infrared light and green light are output from the Brewster angle cut surface of the third-harmonic crystal 7. At this time, the infrared power can be output from 0.1 to 30W, and the green light can be output from 0.1 to 20W.

[0054] Example 5: Simultaneous Output of Infrared, Ultraviolet, and Green Light The multi-wavelength output nanosecond laser of Example 5 includes a pump source 1, a pump coupling device 2, a pump end mirror 3, a gain crystal 4, a Q-switching device 5, a transition mirror 6, a third harmonic crystal 7, a second harmonic crystal 8, and a tail end mirror 9. Along the light emission direction of pump source 1, pump source 1, pump coupling device 2, pump end mirror 3, gain crystal 4, Q-switching device 5 and deflection mirror 6 are arranged in sequence; along the reflection direction of deflection mirror 6, deflection mirror 6, third harmonic crystal 7, second harmonic crystal 8 and tail end mirror 9 are arranged in sequence.

[0055] The system comprises: Pump source 1: an 808nm semiconductor laser; Pump coupling device 2: an inner lens assembly coated with an 808nm high-transmittance pump light film (transmittance ≥99%); Pump end mirror 3: a plano-concave lens, with the end face facing pump source 1 coated with an 808nm high-transmittance pump light film (transmittance ≥99%) and the end face facing away coated with an 808nm high-transmittance pump light film (transmittance ≥99%) + a 1064nm fundamental frequency high-reflection film (reflectivity ≥99.8%). Gain Crystal 4: Nd:YLF crystal, with 808nm pump light high-transmittance film (transmittance ≥99%) + 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on both ends; Q-switching device 5: acousto-optic Q crystal, with 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) deposited on the light-transmitting surface; Conversion Mirror 6: Plane mirror, with 1064nm fundamental frequency high-reflectance film (reflectivity ≥99.8%) deposited; Third Harmonic Crystal 7: LBO crystal, with a Brewster corner facet coated with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + a 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%) + a 355nm third-harmonic high-transmittance film (transmittance ≥99.8%), and a planar facet coated with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + a 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%); second-harmonic crystal 8: LBO crystal, Both ends are coated with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%) + a 532nm frequency-doubled high-transmittance film (transmittance ≥99.8%); Tail end mirror 9: a plane mirror, with the end face facing the second-doubled crystal 8 coated with a 1064nm fundamental frequency partial reflective film (transmittance 15%) + a 532nm frequency-doubled high reflective film (reflectance ≥99.8%), and the end face facing away from the crystal is coated with a 1064nm fundamental frequency high-transmittance film (transmittance ≥99.8%).

[0056] The transmittance of the fundamental frequency reflective film of the tail end mirror 9 is set to 15%, the transmittance of the frequency-doubled light is 0%-2%, the temperature of the second-harmonic crystal 8 is controlled at 45℃, the temperature of the third-harmonic crystal 7 is controlled at 45℃, and the appropriate wavelength of the pump light is adjusted so that infrared light, green light and ultraviolet light are output from the Brewster angle cut surface of the third-harmonic crystal 7. At this time, the infrared power output can be 0.1-30W, the green light output can be 0.1-30W, and the ultraviolet light output can be 0.1-20W.

[0057] Performance tests were conducted using the laser described in Example 5. The repetition frequency of the laser was adjusted from 20kHz to 160kHz. At each frequency, the output power at 1064nm (infrared), 532nm (green light), and 355nm (ultraviolet) was measured. The pulse width at these three wavelengths was also measured. The resulting power-pulse width-repetition frequency characteristic curves are shown below. Figure 2As shown, the provided laser has stable output across multiple wavelengths within the repetition frequency range, without any power interruption or sudden power drop. Furthermore, the infrared (1064nm) power steadily increases with the repetition frequency, while the green (532nm) and ultraviolet (355nm) power remains within the practical range (0.1-30W), indicating high energy conversion efficiency that meets performance requirements. The pulse width of each wavelength changes smoothly with the repetition frequency without drastic fluctuations, demonstrating the stability of the resonant cavity and ensuring accuracy in processing, testing, and other scenarios.

[0058] The multi-wavelength output nanosecond laser provided in this application can simultaneously output multi-wavelength, power-pulse-width-adjustable nanosecond lasers by controlling the transmittance of the output lens film at the tail end, and can also obtain the maximum power of each wavelength by adjusting the temperature of the third-harmonic crystal 7 and the second-harmonic crystal 8.

[0059] The preferred embodiments of this application have been described in detail above, but the invention of this application is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A nanosecond laser with multi-wavelength output, characterized in that, It includes a pump source (1), a pump coupling device (2), a pump end mirror (3), a gain crystal (4), a Q-switching device (5), a transition mirror (6), a third harmonic crystal (7), a second harmonic crystal (8), and a tail end mirror (9). Along the light emission direction of the pump source (1), the pump source (1), the pump coupling device (2), the pump end mirror (3), the gain crystal (4), the Q-switching device (5) and the turning mirror (6) are arranged sequentially. Along the reflection direction of the conversion mirror (6), the third harmonic crystal (7), the second harmonic crystal (8) and the tail end mirror (9) are arranged sequentially. The tail end mirror (9) is a plane mirror. The end face of the tail end mirror (9) facing the second-harmonic crystal (8) is coated with a fundamental frequency light partial reflection film and a second-harmonic light high reflection film. The transmittance of the fundamental frequency light partial reflection film is 2%-98%.

2. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, The Q-switching device (5) is one of an acousto-optic crystal or an electro-optic crystal.

3. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, The pump coupling device (2) is equipped with a lens group, each coated with a high-transmittance pump light film, for shaping the pump light.

4. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, The pump end mirror (3) is one of a plano-convex lens, a plano-concave lens, or a plane mirror; The pump end mirror (3) is coated with a pump light transmission film on the end face facing the pump source (1), and a pump light high transmission film and a fundamental frequency light high reflection film on the end face facing away from the pump source (1).

5. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, The gain crystal (4) is coated with a high-transmittance film for fundamental frequency light and a high-transmittance film for pump light.

6. The nanosecond laser with multi-wavelength output according to claim 5, characterized in that, The gain crystal (4) is made of one of the following materials: neodymium yttrium vanadate crystal, neodymium yttrium aluminum garnet crystal, ytterbium yttrium aluminum garnet crystal, neodymium gadolinium vanadate crystal, or neodymium lithium fluoride yttrium crystal.

7. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, One end of the third harmonic crystal (7) is cut at Brewster's angle, with a smooth cut surface and an orientation corresponding to the turning mirror (6). The other end of the third harmonic crystal (7) is a plane facing the second harmonic crystal (8) and is coated with a fundamental frequency high-transmittance film and a second harmonic high-transmittance film.

8. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, The material of the third harmonic crystal (7) is one of lithium triborate, potassium titanium oxyphosphate, β-phase barium metaborate crystal or periodically polarized lithium niobate crystal.

9. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, Both ends of the second-harmonic crystal (8) are coated with a high-transmittance film for the fundamental frequency and a high-transmittance film for the second-harmonic frequency. The second harmonic crystal (8) is made of one of the following materials: lithium triborate, potassium titanium oxyphosphate, β-phase barium metaborate crystal, or periodically polarized lithium niobate crystal.

10. The nanosecond laser with multi-wavelength output according to claim 1, characterized in that, The end face of the tail end mirror (9) opposite to the second harmonic crystal (8) is coated with a high-transmittance film for the fundamental frequency.

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