A dual LD ​​pumped alternating working pulse solid-state laser without temperature control

Abstract

The present invention discloses a dual LD ​​pumped alternating working temperature-controlled pulse solid-state laser, comprising a total reflection mirror, a first wave plate, a first pumping laser module, a first wedge mirror group, a second pumping laser module, a corner cube prism, a polarizer, an electro-optical Q-switching component, a second wedge mirror group and an output mirror arranged in sequence, wherein the output mirror and the total reflection mirror together constitute a resonant cavity, the first pumping laser module comprises a multi-wavelength LD bar array 1 and a Nd:YAG slab crystal 1 arranged in parallel, the second pumping laser module comprises a multi-wavelength LD bar array 2 and a Nd:YAG slab crystal 2 arranged in parallel, and the electro-optical Q-switching component comprises a second wave plate and a Q-switching crystal arranged in sequence on the output optical path of the polarizer. The present invention solves the problems of laser energy decline and continuous irradiation instability at high temperature by alternating dual multi-wavelength LD bar arrays and optimizing the optical path, thereby improving the stability and output continuity of the laser.

Description

Technical Field

[0001] The invention relates to the technical field of laser diode pumped all-solid-state lasers, in particular to a dual-LD pumped alternately working temperature-control-free pulse solid-state laser. Background Art

[0002] As the core laser equipment of laser guidance, laser light finders play a vital role in modern military and scientific research fields. With the continuous advancement of technology, optoelectronic pods of various types of platforms are also constantly upgraded and modified to adapt to wider and more complex application scenarios. In this context, there is a growing demand in China for laser light finders that are miniaturized, lightweight, low power, and ready to use. However, the design of a laser light finder is not easy. The core design difficulty lies in the design of its light source, that is, the pulsed solid-state laser. In order to meet the requirements of low power consumption and ready to use, the laser needs to adopt a temperature-free design solution.

[0003] Temperature-free lasers refer to pulsed lasers that can work normally and output a certain amount of energy without the need for conventional semiconductor refrigeration (TEC) cooling or heating to a specific temperature control point. The advantage of this design is that by eliminating the high-power TEC device, the main power of the laser only includes the power consumption of the LD pump source and part of the circuit board, so it has the characteristics of low power consumption. At the same time, due to the reduction of laser waste heat, the heat dissipation requirements are also reduced accordingly, and the area of ​​the laser's heat dissipation fins can be reduced, making the entire machine more compact and lightweight.

[0004] Although temperature-free control achieves low power consumption, it also brings a series of technical difficulties.

[0005] First, because the laser does not have strict temperature control measures, the laser energy fluctuation is much larger than that of a laser with temperature control. Domestic laser photometer products usually have strict requirements on laser energy, requiring that the energy fluctuation calculated according to the PV value calculation method (i.e. the difference between the maximum and minimum laser energy values ​​divided by 2, and then divided by the average value) should not exceed 10%. This requirement is much higher than the case of using the standard deviation algorithm to calculate energy fluctuations, so controlling laser energy fluctuations has become the primary difficulty of temperature-free pulsed solid-state lasers.

[0006] Secondly, temperature-free lasers need to meet the requirement of being ready to use. Especially in extremely low temperature environments, such as -40°C or even -45°C, the laser needs to be able to output pulsed lasers with specific energy requirements within a short period of time, such as 3 to 5 seconds, after the whole machine is powered on and the routine communication self-test is completed without temperature control heating. This requirement poses new challenges to the design of traditional LD ​​pump sources.

[0007] In response to the above two difficulties, patent documents with application numbers CN201610165642.6, CN201911249367.6, CN202223089416.4 and CN202123165108.0 have improved the stability and energy output of the laser to a certain extent by adopting multi-wavelength LD pumping, optimizing crystal absorption characteristics and heat dissipation design. However, these methods still expose significant shortcomings when facing continuous operation under long-term, high-frequency (such as 20Hz) and extreme temperature (such as 70°C) conditions.

[0008] Specifically, these patents mainly rely on the multi-wavelength characteristics of the LD bar array to ensure effective absorption of pump light at different temperatures, thereby maintaining the stability of the laser output. However, as the ambient temperature rises, the wavelength of the LD bar array will drift. Although Nd:YAG slab crystals have effective absorption in a wide wavelength range (780nm~820nm), the absorption coefficient drops sharply beyond this range, resulting in a significant loss of laser energy. In addition, due to the volume and weight requirements of the airborne platform, the design space of the radiator is extremely limited, making it difficult to effectively deal with the increase in temperature of the LD bar array caused by long-term operation, which in turn causes a series of problems such as decreased laser energy, increased energy fluctuations, and damage to LD bar array components.

[0009] In particular, under high temperature and long-period irradiation conditions, the temperature of the LD bar array rises rapidly. Without an effective temperature control mechanism (such as TEC active cooling), the power of the LD bar array will drop sharply, and may even be damaged by overheating, severely limiting the continuous working ability and service life of the laser. Therefore, the traditional strategy of sacrificing the temperature stability of the LD bar array to meet the energy demand is not feasible in practical applications and is difficult to meet the strict requirements of airborne laser light finders under high temperature, high frequency and long-period irradiation. Summary of the invention

[0010] In view of this, the present invention aims to address the deficiencies in the prior art, and its main purpose is to provide a dual LD ​​pumped alternating working temperature-controlled pulse solid-state laser, which solves the technical problems of laser energy drop in high temperature environment and difficulty in achieving continuous and stable irradiation for multiple cycles.

[0011] To achieve the above purpose, the present invention adopts the following technical solutions:

[0012] The present invention discloses a dual-LD pumped alternating working temperature-control-free pulse solid-state laser, wherein a resonant cavity is provided inside the solid-state laser, and the solid-state laser comprises:

[0013] A total reflection mirror, arranged at the reflection end of the resonant cavity, used as a reflection mirror of the resonant cavity;

[0014] A first wave plate, arranged at the light path reflection end of the total reflection mirror, for compensating for the depolarization effect caused by the total reflection mirror;

[0015] A first pump laser module is arranged on the output optical path of the first wave plate and is used as a pump source and a pump working substance required for generating laser light;

[0016] A first wedge mirror assembly is arranged on the output optical path of the first pump laser module and is used for fine-tuning the laser optical path emitted from the first pump laser module;

[0017] A second pump laser module is arranged on the output optical path of the first wedge mirror group and serves as a pump source and a pump working substance for alternately working with the first pump laser module to generate laser light;

[0018] A corner cube prism is arranged on the output optical path of the second pump laser module and is used to fold the laser optical path so that the resonant cavity is U-shaped;

[0019] A polarizer, arranged on the output light path of the corner cube prism, for generating linearly polarized light;

[0020] An electro-optical Q-switching component is arranged on the output optical path of the polarizer, and is used to adjust the polarization state of the light beam and output high-energy short-pulse laser;

[0021] A second wedge mirror group is arranged on the output optical path of the electro-optical Q-switching component and is used for fine-tuning the high-energy short-pulse laser optical path output by the electro-optical Q-switching component;

[0022] The output mirror is arranged on the output light path of the second wedge mirror group and located at the output end of the resonant cavity, is used for outputting laser light, and together with the total reflection mirror forms the resonant cavity.

[0023] As a preferred solution, the first pump laser module comprises a multi-wavelength LD bar array 1 and a Nd:YAG slab crystal 1 which are arranged in parallel, wherein the multi-wavelength LD bar array 1 is arranged on one side of the long side of the Nd:YAG slab crystal 1 to provide pump light, and the Nd:YAG slab crystal 1 is arranged on the output optical path of the first wave plate to serve as a pump working material of the multi-wavelength LD bar array 1 and generate laser light;

[0024] The second pump laser module comprises a second multi-wavelength LD bar array and a second Nd:YAG slab crystal which are arranged in parallel. The second multi-wavelength LD bar array is arranged on one side of the long side of the second Nd:YAG slab crystal and is used to work alternately with the first multi-wavelength LD bar array. The second Nd:YAG slab crystal is arranged on the output optical path of the first wedge mirror group and is used as a pump working material of the second multi-wavelength LD bar array and works alternately with the first Nd:YAG slab crystal to generate laser.

[0025] The electro-optical Q-switching component comprises a second wave plate and a Q-switching crystal which are sequentially arranged on the output light path of the polarizer, wherein the second wave plate is used to adjust the polarization state of the light beam, and the Q-switching crystal is used to generate high-energy short-pulse laser.

[0026] As a preferred solution, the multi-wavelength LD bar array one and the multi-wavelength LD bar array two both use 3 to 6 wavelengths in the range of 790nm to 816nm, the loading power of the multi-wavelength LD bar array one and the multi-wavelength LD bar array two is 3kW to 6kW, and the second wave plate is a λ / 4 wave plate.

[0027] As a preferred embodiment, the Nd:YAG slat crystal 1 and the Nd:YAG slat crystal 2 are both inverted trapezoids, and one of the long sides of the trapezoids of the Nd:YAG slat crystal 1 and the Nd:YAG slat crystal 2 is a pumping surface, and the pumping surface is coated with an anti-reflection film. The short sides of the trapezoids of the Nd:YAG slat crystal 1 and the Nd:YAG slat crystal 2 are both fixed surfaces, and the fixed surfaces are coated with a high reflection layer, an evanescent wave layer and a welding layer in sequence, and the high reflection layer is arranged on a side of the fixed surface close to the pumping surface, and one side of the multi-wavelength LD bar array 1 and the multi-wavelength LD bar array 2 close to the Nd:YAG slat crystal 1 and the Nd:YAG slat crystal 2 respectively are both light-emitting surfaces.

[0028] As a preferred solution, the thickness of the anti-reflection film is 760nm~820nm, the high-reflection layer is a high-reflection film, the thickness of the high-reflection layer is 760nm~820nm, the evanescent wave layer is an evanescent wave film, the welding layer is used for welding and fixing, and the distance from the light-emitting surface to the pump surface is 0.8mm~1.4mm.

[0029] As a preferred solution, it also includes a main control circuit board, which is electrically connected to the multi-wavelength LD bar array 1 and the multi-wavelength LD bar array 2 through LD driving circuit A and LD driving circuit B respectively, and the main control circuit board is also electrically connected to the Q-switched crystal through a Q-switched high-voltage circuit.

[0030] As a preferred solution, the first wedge mirror group and the second wedge mirror group are both composed of two wedge mirror pieces with high flatness.

[0031] As a preferred solution, the wedge angle of the wedge mirror is 15'.

[0032] As a preferred solution, the total reflection mirror is a total reflection Porro prism, the output mirror is a concave-convex mirror, and the first wave plate is a 0.57λ wave plate.

[0033] As a preferred solution, the output mirror is a VRM Gaussian mirror.

[0034] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that it mainly has the following advantages:

[0035] 1. Dual LD ​​pumping alternating working mechanism to achieve multiple cycles of continuous and stable irradiation: By adopting two multi-wavelength LD bar arrays, the working mode of alternating pumping of Nd:YAG slab crystal is realized. When one multi-wavelength LD bar array is in working state and generating laser, the other multi-wavelength LD bar array is in non-working state, which can fully dissipate heat and cool down. This alternating working strategy not only effectively avoids the problem of overheating of the multi-wavelength LD bar array due to continuous operation, but also enables the laser to achieve multiple cycles of continuous irradiation at a repetition frequency of 20Hz at an ambient temperature of up to 70°C, significantly improving the stability and reliability of the laser;

[0036] 2. Effectively solve the problem of light path deflection and depolarization: Two Nd:YAG slab crystals are configured in the laser resonator. After the light path of Nd:YAG slab crystal 1 is adjusted, Nd:YAG slab crystal 2 and the first wedge lens group are placed. By adjusting the first wedge lens group, it is ensured that the light path can enter Nd:YAG slab crystal 2 with normal incidence, thereby maintaining the constant output of laser energy. In addition, the first wave plate is configured in front of the total reflection mirror to compensate for the depolarization effect caused by the light path adjustment and the total reflection of the Porro prism, ensuring that the laser can still maintain the polarization state in the p direction before entering Nd:YAG slab crystal 1, thereby effectively solving the problem of light path deflection and depolarization;

[0037] 3. Independent design and optimization of LD driving circuit: By designing independent driving circuits for the two multi-wavelength LD bar arrays, it not only reduces the complexity of hardware circuit design, but also significantly improves the reliability of the main control circuit board and the multi-wavelength LD bar array. By flexibly setting the trigger delay of the two multi-wavelength LD bar arrays to switch the trigger signal, the alternating working timing of the multi-wavelength LD bar array can be accurately controlled, thereby ensuring the efficient and stable operation of the laser while reducing the overall energy consumption and cost of the system. This design strategy not only improves the performance and reliability of the laser, but also facilitates subsequent system maintenance and upgrades.

[0038] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the structure of a dual LD ​​pumped alternating working temperature-control-free pulse solid-state laser according to an embodiment of the present application;

[0040] Figure 2 This is a schematic diagram of a dual LD ​​pumped alternating working temperature-free pulse solid laser resonator according to an embodiment of the present application;

[0041] Figure 3 It is a schematic diagram of a MOPA laser resonant cavity combining an LD end pump and a side pump according to an embodiment of the present application;

[0042] Figure 4 This is a timing diagram of laser periodic irradiation of an embodiment of the present application;

[0043] Figure 5 This is a timing diagram of the laser irradiating light in 10 cycles according to the embodiment of the present application.

[0044] Description of reference numerals:

[0045] 1. Full reflective mirror;

[0046] 2. The first wave;

[0047] 3. A first pump laser module; 301. A multi-wavelength LD bar array; 302. A Nd:YAG slab crystal;

[0048] 4. The first wedge lens group;

[0049] 5. The second pump laser module; 501. The second multi-wavelength LD bar array; 502. The second Nd:YAG slab crystal;

[0050] 6. Corner cube prism;

[0051] 7. Polarizer;

[0052] 8. Electro-optical Q-switching component; 801. second wave plate; 802. Q-switching crystal;

[0053] 9. Second wedge lens group;

[0054] 10. Output mirror. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0056] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0057] As the core laser equipment of laser guidance technology, the performance requirements of laser light finders have been increasing in recent years with the upgrade and innovation of optoelectronic pod systems of various platforms. Domestic scientific research institutions and units are currently focusing on the research and development of laser light finders that are miniaturized, lightweight, low-power, and instant-on. In the core design of such equipment, the most critical technical challenge lies in the design of the light source - pulsed solid-state laser. In view of the dual requirements of low power consumption and instant start, the laser must adopt a temperature-free design strategy to ensure its stable and efficient performance.

[0058] Temperature-free lasers refer to laser devices that do not rely on traditional semiconductor refrigeration chips (TECs) for precise temperature control and can still work stably and output certain energy pulses in different environments. By omitting the high-power TEC components, the total power consumption of this type of laser is mainly concentrated on the LD pump source and some circuit losses, thus achieving low power consumption characteristics. At the same time, due to the reduction in waste heat generation, the heat dissipation requirements of the laser are reduced, and the area of ​​the heat sink fins can be reduced, further promoting the miniaturization of the equipment. However, while the temperature-free design brings the advantage of low power consumption, it also brings significant design challenges, especially when it is required to achieve out-of-the-box functionality. These challenges are particularly prominent.

[0059] First, the lack of strict temperature control leads to a significant increase in laser energy fluctuations compared to temperature-controlled lasers. Domestic laser photometers usually evaluate energy stability based on PV values, requiring no more than 10%, which is stricter than the energy fluctuation requirement based on standard deviation calculation. Therefore, how to effectively control laser energy fluctuations has become the primary technical challenge for temperature-free pulsed solid-state lasers.

[0060] Secondly, the instant-on function requires that the laser can output pulsed lasers that meet specific energy requirements in a short time, such as 3 to 5 seconds, after the whole machine is powered on and the communication self-test is completed in an extremely low temperature environment, such as -40°C to -45°C, without preheating. This poses a new challenge to the design of the LD pump source, requiring it to start quickly and reach a stable working state at low temperatures.

[0061] In response to the above technical difficulties, a variety of technical solutions have been proposed and put into practice in China, and these solutions are recorded in journals and patents in the field of laser optics. For example, the patent application number CN201610165642.6 is a multi-wavelength pumped temperature-free solid-state laser and a multi-wavelength selection method. It uses multi-wavelength pumping technology and combines the LD end pump crystal rod design to ensure that the crystal can maintain a certain absorption coefficient under different wavelengths of pump light, thereby maintaining a stable output of laser energy and realizing a temperature-free design. Similarly, a high-repetition-rate, temperature-free semiconductor-pumped 1064nm disk laser with patent application number CN201911249367.6, a temperature-free and debugging-free solid-state laser with patent application number CN202223089416.4, and a resonant cavity and an all-solid-state laser with patent application number CN202123165108.0 also adopt a multi-wavelength LD pumping strategy, some of which achieve the design goal of a temperature-free laser through the good heat dissipation characteristics of the disk crystal, and some through the full absorption of the LD angle-pumped slab crystal.

[0062] Although domestic papers and patent documents have disclosed the design of temperature-free lasers and solved some design difficulties, the existing technical solutions still have significant shortcomings in dealing with specific application scenarios, especially the pulsed solid lasers required for laser light finders. In particular, the problem of periodic irradiation time at a repetition frequency of 20Hz, and the strict requirements of the airborne platform for laser energy (up to 130mJ) and continuous multiple cycle emission time (including 10 short cycles and 4 long cycles), the existing temperature-free laser solutions are difficult to meet.

[0063] Especially in a high temperature environment of 70°C, the design of temperature-free lasers faces great challenges. The aforementioned disclosed invention patents are mainly based on LD multi-wavelength pumping technology to ensure that the LD can fully absorb and maintain a certain energy output at different temperatures. However, these solutions are mainly suitable for application scenarios with shorter laser emission time and a certain temperature range. When faced with longer light emission time, especially in a high temperature environment, the wavelength of the LD will drift significantly. For example, according to the temperature drift coefficient of 0.28nm / °C, the 808nm LD will rise to above 820nm at 70°C, and the effective absorption wavelength range of the Nd:YAG crystal near 800nm ​​is limited, generally 780nm~820nm, and the absorption coefficient drops sharply beyond this range.

[0064] To solve this problem, designers usually choose to combine LD bars with lower wavelengths at room temperature. However, this approach needs to take into account low-temperature performance, so the long-wavelength LD bars also need to maintain a certain power, resulting in a significant increase in the power demand of a single multi-wavelength LD bar array. This not only increases the heat dissipation pressure, but also increases the load voltage due to the increase in the number of LD bars in series, which in turn increases the difficulty of LD circuit design.

[0065] What is more serious is that in a high temperature environment of 70°C, due to the lack of active TEC cooling, the temperature of the LD bar array gradually rises with the light emission time. When the volume and weight of the whole machine are strictly limited, the size of the heat sink is limited, causing the temperature of the LD bar array to quickly rise to about 80°C. At this time, the laser energy drops rapidly, the average energy decreases, and the laser energy fluctuation exceeds the specified 10% range. In addition, long-term high-temperature operation will cause the LD bar power to drop, and even burn some LD bar chips, seriously affecting the life of the whole machine.

[0066] Therefore, the technical solution of allowing the LD bar temperature to rise to maintain the laser energy is not feasible under the requirement of 20Hz continuous long-period irradiation. Once the LD bar temperature rises to about 80℃, power-off protection is required, otherwise the LD bar will be damaged or the power will drop.

[0067] To solve the above problems, please refer to Figures 1 to 5 The embodiment of the present invention provides a dual LD ​​pumped alternating working temperature-controlled pulse solid laser, wherein a resonant cavity is provided in the solid laser, and the solid laser comprises:

[0068] The total reflection mirror 1 is arranged at the reflection end of the resonant cavity and is used as a reflection mirror of the resonant cavity.

[0069] The first wave plate 2 is arranged at the light path reflection end of the total reflection mirror 1 to compensate for the depolarization effect caused by the total reflection mirror 1 and ensure the stability of the polarization state of the laser.

[0070] The first pump laser module 3 is arranged on the output optical path of the first wave plate 2 and is used as a pump source and a pump working substance required for generating laser.

[0071] The first wedge mirror assembly 4 is disposed on the output optical path of the first pump laser module 3 and is used for fine-tuning the optical path of the laser emitted from the first pump laser module 3 .

[0072] The second pump laser module 5 is arranged on the output optical path of the first wedge mirror group 4, and is used as a pump source and a pump working substance to work alternately with the first pump laser module 3 to generate laser light, thereby achieving continuous and stable laser output and reducing the heat accumulation of a single pump source. The design of the first wedge mirror group 4 ensures that the laser light emitted by the first pump laser module 3 can be accurately incident on the second pump laser module 5.

[0073] The corner cube prism 6 is arranged on the output optical path of the second pump laser module 5, and is used to fold the laser optical path to make the resonant cavity U-shaped, that is, the device in the resonant cavity is divided into two arms for placement, which effectively shortens the mechanical length of the solid-state laser, improves the compactness of the structure, and is conducive to anti-detuning, enhances the optical path stability of the solid-state laser in high and low temperature and vibration and shock environments, and ensures the constancy of the laser output energy.

[0074] The polarizer 7 is arranged on the output light path of the corner cube prism 6 to generate linearly polarized light and improve the coherence and directivity of the laser.

[0075] The electro-optical Q-switching component 8 is arranged on the output optical path of the polarizer 7 to adjust the polarization state of the light beam and output high-energy short-pulse laser to achieve precise control and optimization of the laser pulse.

[0076] The second wedge mirror group 9 is arranged on the output optical path of the electro-optical Q-switching component 8 to fine-tune the high-energy short-pulse laser optical path output by the electro-optical Q-switching component 8 to ensure that the laser is accurately focused on the output mirror 10.

[0077] The output mirror 10 is arranged on the output optical path of the second wedge mirror group 9 and at the output end of the resonant cavity, and is used to output the laser. It forms a resonant cavity together with the total reflection mirror 1 to ensure that the laser forms stable oscillation and amplification in the resonant cavity.

[0078] In this embodiment, the first pump laser module 3 includes a multi-wavelength LD bar array 301 and a Nd:YAG slab crystal 302 arranged in parallel. The multi-wavelength LD bar array 301 is arranged on one side of the long side of the Nd:YAG slab crystal 302 to provide pump light and achieve efficient energy conversion. The Nd:YAG slab crystal 302 is arranged on the output optical path of the first wave plate 2 to serve as the pump working material of the multi-wavelength LD bar array 301 and generate laser light as the initial laser source of the solid laser.

[0079] The second pump laser module 5 includes a multi-wavelength LD bar array 2 501 and a Nd:YAG slab crystal 2 502 which are arranged in parallel. The multi-wavelength LD bar array 2 501 is arranged on one side of the long side of the Nd:YAG slab crystal 2 502 and is used to work alternately with the multi-wavelength LD bar array 1 301. The Nd:YAG slab crystal 2 502 is arranged on the output optical path of the first wedge mirror group 4 and is used as the pump working material of the multi-wavelength LD bar array 2 501 and works alternately with the Nd:YAG slab crystal 1 302 to generate laser, thereby ensuring the continuity and stability of the laser output.

[0080] The electro-optical Q-switching component 8 includes a second wave plate 801 and a Q-switching crystal 802 which are sequentially arranged on the output light path of the polarizer 7. The second wave plate 801 is used to adjust the polarization state of the light beam to ensure the precise control of the polarization direction of the laser. The Q-switching crystal 802 is used to generate high-energy short-pulse lasers, and realizes the compression of laser pulses and the concentrated output of energy through the rapid switching effect.

[0081] Here, it should be noted that the pump working material, namely the gain medium, is a pump crystal, which is essentially the Nd:YAG slab crystal itself.

[0082] Furthermore, the multi-wavelength LD bar array 1 301 and the multi-wavelength LD bar array 2 501 both use 3 to 6 wavelengths in the range of 790 nm to 816 nm to efficiently match the absorption peak of the Nd:YAG slab crystal, thereby improving the pump efficiency. The loading power of the multi-wavelength LD bar array 1 301 and the multi-wavelength LD bar array 2 501 is 3 kW to 6 kW, ensuring sufficient pump energy to achieve high-power laser output. The second wave plate 801 is a λ / 4 wave plate, which is used to accurately adjust the laser polarization state and realize polarization control in the electro-optical Q-switching process.

[0083] Both the Nd:YAG slab crystal 1 302 and the Nd:YAG slab crystal 2 502 are inverted trapezoidal shapes, which reduce the thermal lens effect inside the Nd:YAG slab crystal and improve the quality of the laser beam. The incident surfaces of the Nd:YAG slab crystal 1 302 and the Nd:YAG slab crystal 2 502 are cut according to the Brewster angle to reduce the reflection loss of the laser at the time of incidence and improve the transmission efficiency of the laser. The long side of the trapezoid of the Nd:YAG slab crystal 1 302 and the Nd:YAG slab crystal 2 502 is the pump surface, and the pump surface is coated with an anti-reflection film to further reduce the reflection of the pump light and improve the pump efficiency. One of the short sides of the trapezoid of Nd:YAG slab crystal 1 302 and Nd:YAG slab crystal 2 502 is a fixed surface, and the fixed surface is coated with a high reflection layer, an evanescent wave layer and a welding layer in sequence. The high reflection layer is arranged on the side of the fixed surface close to the pump surface, which is used to reflect the unabsorbed pump light and improve the utilization rate of the pump light. The multi-wavelength LD bar array 1 301 and the multi-wavelength LD bar array 2 501 are close to the Nd:YAG slab crystal 1 302 and the Nd:YAG slab crystal 2 502 respectively. Both are light-emitting surfaces, which are used to provide uniform and efficient pump light to the Nd:YAG slab crystal.

[0084] Considering that the laser operates in the temperature range of -40℃~70℃, the wavelength of the multi-wavelength LD bar array will change with the ambient temperature, and its variation range is within the range of 760nm~820nm. Therefore, the thickness of the anti-reflection film is designed to be 760nm~820nm to ensure the transmittance of the pump light in the full temperature range. In addition, the high reflection layer is a high reflection film, and the thickness of the high reflection layer is 760nm~820nm, which ensures the reflectivity of the pump light passing through the bottom of the Nd:YAG slab crystal in the full temperature range. The evanescent wave layer is an evanescent wave film, which effectively suppresses the reflection loss of the evanescent wave on the interface of the Nd:YAG slab crystal and improves the coupling efficiency of the pump light inside the Nd:YAG slab crystal. The welding layer is used for welding and fixing to ensure the stable operation of the Nd:YAG slab crystal under high-power pumping. The distance from the light emitting surface to the pumping surface is 0.8 mm to 1.4 mm, ensuring that the pumping light of the multi-wavelength LD bar array can enter the Nd:YAG slab crystal, improving the absorption efficiency of the Nd:YAG slab crystal for the pumping light, and making the pumping light relatively uniform in the Nd:YAG slab crystal.

[0085] See also Figure 3The dual LD ​​pumped alternating working temperature-free pulse solid-state laser also includes a main control circuit board, which is electrically connected to the multi-wavelength LD bar array 1 301 and the multi-wavelength LD bar array 2 501 through the LD drive circuit A and the LD drive circuit B, respectively, to ensure independent and precise control and drive of the two multi-wavelength LD bar arrays. The main control circuit board is also electrically connected to the Q-switched crystal 802 through the Q-switched high-voltage circuit, and this connection ensures the rapid response and precise control of the Q-switching process, thereby realizing flexible adjustment of laser pulse width, repetition frequency and other parameters.

[0086] Specifically, in the operation mechanism of the solid-state laser, the multi-wavelength LD bar array 1 301 and the multi-wavelength LD bar array 2 501 are designed with independent power supply, and are independently driven by the LD drive circuit A and the LD drive circuit B respectively. Both drive circuits are integrated with a 485 communication interface to achieve effective communication with the main control circuit board. In order to generate pulsed light output, the Q-switched high-voltage circuit is responsible for applying a high voltage of a λ / 4 wavelength to the Q-switched crystal 802 built into the solid-state laser to achieve the electro-optical Q-switching function.

[0087] Under the control of the main control circuit board, the two driving circuits can synchronously trigger the Q-switched high-voltage circuit in a predetermined order to achieve power supply switching. The specific process is as follows: First, according to the instructions of the host computer, the main control circuit board activates the LD driving circuit A through the trigger signal A to start the power supply of the multi-wavelength LD bar array 301. In one pumping cycle, the LD current is pumped with a pulse width of 230μm. Next, based on the trigger signal A, the main control circuit board synchronously triggers the Q-switched high-voltage circuit after a delay of 230μm, and the Q-switched high-voltage circuit then applies high voltage to the Q-switched crystal 802, thereby completing a cycle of pulsed light output. During this period, the LD driving circuit B remains in standby mode, and the multi-wavelength LD bar array 2 501 is also in a non-working state. When the multi-wavelength LD bar array 1 301 completes the laser output and enters the rest interval, the multi-wavelength LD bar array 2 501 begins to enter the working state. The main control circuit board activates the LD driving circuit B through the trigger signal B, and then synchronously triggers the Q-switched high-voltage circuit according to the set delay time to achieve the pulse light output of the multi-wavelength LD bar array 2 501. This process is alternately performed between the two multi-wavelength LD bar arrays, ensuring that each multi-wavelength LD bar array can get more adequate rest time, thereby improving the overall work efficiency and stability.

[0088] See also Figure 4 , assuming that the single laser cycle emission time of the laser light detector is T , the interval between adjacent cycles is ΔT The specific process is as follows: The main control circuit board first triggers the multi-wavelength LD bar array 301 to continuously emit light at a frequency of 20Hz. T time. Then, the system enters ΔT Then, the main control circuit board turns to trigger the multi-wavelength LD bar array 2 501, which also emits light at a frequency of 20Hz. T Time, then experience another ΔT After that, the process returns to the multi-wavelength LD bar array 1 301, and the cycle repeats.

[0089] In this mode, each multi-wavelength LD bar array completes a light emission cycle. T After that, actually enjoy T+2ΔT The rest time of the laser system is still maintained in the light-intermittent mode. T out of light, ΔT The regularity of intervals.

[0090] by Figure 5 Taking the parameters in as an example, if the light emission time of a single cycle is set to 60 seconds, that is T =60s, the interval is 10 seconds, that is ΔT =10s, then according to the design of the present invention, the actual working time of each multi-wavelength LD bar array is 60 seconds, and the rest interval is extended to 80 seconds, that is, T +2 ΔT = 80s. This extended rest time, 80 seconds, is sufficient to ensure effective heat dissipation of the LD component and maintain its operation at a lower temperature level.

[0091] Furthermore, in combination with a laser energy control method and related equipment with patent application number CN202211309935.9, by accurately fitting the control curve between the LD current pulse width and the LD temperature, it is possible to achieve stable control of the laser energy in each cycle, so that the fluctuation range is kept within about 5%, and support stable irradiation for more than 10 consecutive cycles.

[0092] Furthermore, the first wedge mirror group 4 and the second wedge mirror group 9 are both composed of two high-flatness wedge mirror components, so that the laser remains incident at normal incidence into the Nd:YAG slab crystal 2 502 after being emitted through the Nd:YAG slab crystal 1 302, ensuring that the laser is still incident at the Brewster angle, thereby improving the conversion efficiency of the pump light.

[0093] The wedge angle of the wedge mirror is 15', and the material of the wedge mirror is quartz.

[0094] The total reflection mirror 1 is a total reflection Porro prism, the output mirror 10 is a concave-convex mirror, and the first wave plate 2 is a 0.57λ wave plate, which ensures that the laser is still polarized in the p direction when it enters the Nd:YAG slab crystal 302 after being totally reflected by the total reflection Porro prism. Figure 2 In the placement direction of the Nd:YAG slab crystal 302, the p direction is the vertical direction.

[0095] The output mirror 10 is a VRM Gaussian mirror, that is, a refractive index gradient reflector, and its curvature radius is designed according to the cavity length of the resonant cavity and the slab crystal thermal lens.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dual-LD pumped alternating working temperature-free pulse solid laser, wherein a resonant cavity is provided in the solid laser, characterized in that: The solid-state laser comprises: A total reflection mirror (1), arranged at the reflection end of the resonant cavity, used as a reflection mirror of the resonant cavity; A first wave plate (2) is arranged at the light path reflection end of the total reflection mirror (1) and is used to compensate for the depolarization effect caused by the total reflection mirror (1); A first pump laser module (3) is arranged on the output optical path of the first wave plate (2) and is used as a pump source and a pump working substance required for generating laser light; A first wedge mirror group (4) is arranged on the output optical path of the first pump laser module (3) and is used to fine-tune the optical path of the laser emitted from the first pump laser module (3); A second pump laser module (5) is arranged on the output optical path of the first wedge mirror group (4) and serves as a pump source and a pump working substance for working alternately with the first pump laser module (3) to generate laser light; A corner cube prism (6) is arranged on the output optical path of the second pump laser module (5) and is used to fold the laser optical path so that the resonant cavity is U-shaped; A polarizing plate (7), arranged on the output light path of the corner cube prism (6), and used for generating linearly polarized light; An electro-optical Q-switching component (8) is arranged on the output light path of the polarizer (7) and is used to adjust the polarization state of the light beam and output high-energy short-pulse laser light; A second wedge mirror group (9) is arranged on the output optical path of the electro-optical Q-switching component (8) and is used to fine-tune the high-energy short-pulse laser optical path output by the electro-optical Q-switching component (8); The output mirror (10) is arranged on the output light path of the second wedge mirror group (9) and is located at the output end of the resonant cavity, is used for outputting laser light, and together with the total reflection mirror (1) forms the resonant cavity.

2. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 1, characterized in that: The first pump laser module (3) comprises a multi-wavelength LD bar array (301) and a Nd:YAG slab crystal (302) arranged in parallel, wherein the multi-wavelength LD bar array (301) is arranged on one side of the long side of the Nd:YAG slab crystal (302) to provide pump light, and the Nd:YAG slab crystal (302) is arranged on the output light path of the first wave plate (2) to serve as a pump working material of the multi-wavelength LD bar array (301) and generate laser light; The second pump laser module (5) comprises a second multi-wavelength LD bar array (501) and a second Nd:YAG slab crystal (502) arranged in parallel, wherein the second multi-wavelength LD bar array (501) is arranged on one side of the long side of the second Nd:YAG slab crystal (502) and is used to work alternately with the first multi-wavelength LD bar array (301), and the second Nd:YAG slab crystal (502) is arranged on the output optical path of the first wedge mirror group (4) and is used as a pump working material of the second multi-wavelength LD bar array (501) and works alternately with the first Nd:YAG slab crystal (302) to generate laser light; The electro-optical Q-switching component (8) comprises a second wave plate (801) and a Q-switching crystal (802) which are sequentially arranged on the output light path of the polarizing plate (7); the second wave plate (801) is used to adjust the polarization state of the light beam; and the Q-switching crystal (802) is used to generate high-energy short-pulse laser light.

3. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 2, characterized in that: The multi-wavelength LD bar array one (301) and the multi-wavelength LD bar array two (501) both use 3 to 6 wavelengths in the range of 790 nm to 816 nm, the loading power of the multi-wavelength LD bar array one (301) and the multi-wavelength LD bar array two (501) is 3 kW to 6 kW, and the second wave plate (801) is a λ / 4 wave plate.

4. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 2, characterized in that: The Nd:YAG slat crystal 1 (302) and the Nd:YAG slat crystal 2 (502) are both inverted trapezoids, and the long sides of the trapezoids of the Nd:YAG slat crystal 1 (302) and the Nd:YAG slat crystal 2 (502) are both pumping surfaces, and the pumping surfaces are coated with anti-reflection films. The short sides of the trapezoids of the Nd:YAG slat crystal 1 (302) and the Nd:YAG slat crystal 2 (502) are both fixed surfaces, and the fixed surfaces are coated with a high reflection layer, an evanescent wave layer and a welding layer in sequence, and the high reflection layer is arranged on a side of the fixed surface close to the pumping surface. The multi-wavelength LD bar array 1 (301) and the multi-wavelength LD bar array 2 (501) are both luminous surfaces.

5. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 4, characterized in that: The thickness of the anti-reflection film is 760nm-820nm, the high-reflection layer is a high-reflection film, the thickness of the high-reflection layer is 760nm-820nm, the evanescent wave layer is an evanescent wave film, the welding layer is used for welding and fixing, and the distance from the light-emitting surface to the pump surface is 0.8mm-1.4mm.

6. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 2, characterized in that: The invention also includes a main control circuit board, which is electrically connected to the multi-wavelength LD bar array 1 (301) and the multi-wavelength LD bar array 2 (501) through an LD driving circuit A and an LD driving circuit B respectively, and the main control circuit board is also electrically connected to the Q-switched crystal (802) through a Q-switched high voltage circuit.

7. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 1, characterized in that: The first wedge mirror group (4) and the second wedge mirror group (9) are both composed of two wedge mirror pieces with high flatness.

8. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 7, characterized in that: The wedge angle of the wedge mirror is 15'.

9. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 1, characterized in that: The total reflection mirror (1) is a total reflection Porro prism, the output mirror (10) is a concave-convex mirror, and the first wave plate (2) is a 0.57λ wave plate.

10. The dual-LD pumped alternating working temperature-control-free pulse solid-state laser according to claim 9, characterized in that: The output mirror (10) is a VRM Gaussian mirror.

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