Laser device

Abstract

The invention discloses a laser, which comprises a pumping source used for generating laser light; the first resonant cavity, the first frequency doubling crystal, the second resonant cavity and the second frequency doubling crystal are sequentially arranged along the optical axis of the laser; the end face of the first resonant cavity is coated and used for outputting laser of a first wavelength. The first frequency doubling crystal is used for performing frequency doubling conversion on the laser of the first wavelength to laser of a first target wavelength, and outputting the laser through the second resonant cavity and the second frequency doubling crystal; the front end face of the second resonant cavity is coated with a film and used for absorbing part of the laser of the first target wavelength, generating laser of a second wavelength and outputting the laser to the second frequency doubling crystal. And the second frequency doubling crystal is used for performing frequency doubling conversion on the laser with the second wavelength to laser with a second target wavelength and outputting the laser. By means of the structure, coaxial output of dual-wavelength laser is achieved, the electro-optical efficiency of the laser is improved, stray light is reduced, the structure is simple, cost is low, and the size of the laser is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of laser radar, and in particular to a laser. Background Art

[0002] Lidar is a remote sensing technology that uses laser beams to measure the distance and speed of objects. The application scenarios of Lidar include at least optical detection of the ocean and detection of cleaner ocean water bodies. In ocean optical detection, seawater has a smaller attenuation coefficient for the incident band of the blue-green band, so the blue-green band is called the ocean transmission window and is often used in ocean Lidar systems. By equipping the blue-green light band laser system, compatible detection of clean ocean water bodies and nearshore water bodies can be achieved. In the detection of cleaner ocean water bodies, as the CDOM content decreases, the attenuation of the water body to the blue light band decreases, so the best detection band shifts to the blue light band. While measuring the water body, red light near 670nm is needed for the detection of marine microorganisms, and more accurate data can be obtained in combination with the inversion algorithm.

[0003] The existing generation of blue-green lasers and red-blue lasers is usually based on optical parametric oscillation (OPO) technology, which generates narrow pulse width lasers from LD-pumped lasers, and then generates two different wavelength lasers after amplification and frequency doubling. One wavelength laser is the target wavelength laser, and then the second target wavelength laser is generated after pumping with another wavelength laser. Finally, the two target wavelength lasers are combined to generate blue-green light or red-blue light. However, each part of the OPO technology requires the shaping spot to match the frequency doubling crystal and the crystal in the OPO technology. The overall structure is relatively complex, with more structural components, higher cost, and poor reliability. In addition, the OPO technology requires multiple frequency conversions and optical path conversions during the laser generation process, which makes the system loss too high, with more stray light and low efficiency. Summary of the invention

[0004] The present invention provides a laser which realizes coaxial output of dual-wavelength lasers through a coaxially arranged structure, improves the electro-optical efficiency of the laser, reduces the generation of stray light, has a simple structure, low cost, and reduces the volume of the laser.

[0005] The present invention provides a laser, comprising a pump source for generating laser light; and further comprising a first resonant cavity, a first frequency doubling crystal, a second resonant cavity and a second frequency doubling crystal which are sequentially arranged along the optical axis of the laser light;

[0006] The end surface of the first resonant cavity is coated to output laser light of a first wavelength;

[0007] The first frequency doubling crystal is used to frequency-double the laser light of the first wavelength to convert it into the laser light of the first target wavelength, and output it through the second resonant cavity and the second frequency doubling crystal;

[0008] The end surface coating of the second resonant cavity is used to absorb part of the laser light of the first target wavelength, generate laser light of the second wavelength, and output it to the second frequency doubling crystal;

[0009] The second frequency doubling crystal is used to frequency-double the laser light of the second wavelength to convert it into the laser light of the second target wavelength and output it.

[0010] Optionally, the laser further comprises a shaping lens assembly;

[0011] The shaping mirror group is located on the optical axis of the laser and is arranged between the pump source and the first resonant cavity; the shaping mirror group is used to shape and focus the laser so that the wavelength of the pump source and the first resonant cavity are matched and the laser of the first wavelength is output.

[0012] Optionally, the shaping lens assembly includes one of a single lens, a lens group, an aspherical lens and a light guide cone.

[0013] Optionally, the second resonant cavity includes a laser medium, an FP etalon, and an output mirror;

[0014] The laser medium, the FP etalon and the output mirror are all located on the optical axis of the laser and are sequentially arranged between the first frequency doubling crystal and the second frequency doubling crystal;

[0015] The laser medium is used to absorb part of the laser light of the first target wavelength and generate laser light of the second wavelength range;

[0016] The FP etalon is used to narrow the laser line width in the second wavelength range and select the laser of the second wavelength;

[0017] The output mirror is used to generate and output laser light of a second wavelength.

[0018] Optionally, the material of the laser medium is titanium sapphire, the first wavelength is 1064nm, the first target wavelength is 532nm, and the second wavelength range is 700nm-1000nm.

[0019] Optionally, the laser medium is made of chromium-doped lithium strontium aluminum fluoride laser crystal, the first wavelength is 1340 nm, the first target wavelength is 670 nm, and the second wavelength range is 770 nm-1100 nm.

[0020] Optionally, the front end surface of the output mirror is coated with a high-reflection film for reflecting the laser light of the first target wavelength so that the output mirror outputs the laser light of the second wavelength.

[0021] Optionally, the laser further comprises a filter;

[0022] The filter is located on the optical axis of the laser and is arranged on the side of the second frequency doubling crystal away from the pump source. The filter is used to filter the laser of the first target wavelength to output the laser of the second target wavelength.

[0023] Optionally, the first resonant cavity comprises a bonded crystal.

[0024] Optionally, the bonded crystal includes a crystal combination of neodymium-doped yttrium aluminum garnet and chromium-doped yttrium aluminum garnet or a crystal combination of neodymium-doped yttrium vanadate and vanadium-doped yttrium aluminum garnet.

[0025] The technical solution of the present invention generates laser through a pump source, and the first resonant cavity, the first frequency doubling crystal, the second resonant cavity and the second frequency doubling crystal are arranged in sequence along the optical axis of the laser, so that the laser generated by the pump source can be sent to the first resonant cavity, the first resonant cavity will pump the laser, absorb the pump light spot and output the laser of the first wavelength to the first frequency doubling crystal, the first frequency doubling crystal will double the frequency of the laser of the first wavelength to the laser of the first target wavelength and output it, one part of the laser of the first target wavelength output will be normally output after passing through the second resonant cavity and the second frequency doubling crystal, and the other part of the laser of the first target wavelength will be absorbed by the second resonant cavity after passing through the second resonant cavity, generating a laser of the second wavelength, and the laser of the second wavelength will be sent to the second frequency doubling crystal, and the second frequency doubling crystal will double the frequency of the laser of the second wavelength to the laser of the second target wavelength and output it. With the above structure, through the coaxial setting, the coaxial output of the dual-wavelength laser is realized, the electro-optical efficiency of the laser is improved, the generation of stray light is reduced, the structure is simple, the cost is low, and the volume of the laser is reduced.

[0026] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of the structure of a laser provided by an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of the structure of a second laser provided by an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the structure of a third laser provided by an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of the structure of a fourth laser provided by an embodiment of the present invention;

[0032] Figure 5 A schematic diagram of the structure of a fifth laser provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] In one embodiment, Figure 1 A schematic diagram of the structure of a laser provided in an embodiment of the present invention. This embodiment can be applied to outputting dual-wavelength lasers for use in laser radars. The laser includes a pump source 1 for generating lasers; a first resonant cavity 2, a first frequency doubling crystal 3, a second resonant cavity 4, and a second frequency doubling crystal 5 are sequentially arranged along the optical axis of the laser; the end face of the first resonant cavity 2 is coated for outputting lasers of a first wavelength; the first frequency doubling crystal 3 is used for frequency-double-converting the laser of the first wavelength into lasers of a first target wavelength, and outputting the same through the second resonant cavity 4 and the second frequency doubling crystal 5; the end face of the second resonant cavity 4 is coated for absorbing part of the laser of the first target wavelength, generating lasers of a second wavelength, and outputting the same to the second frequency doubling crystal 5; the second frequency doubling crystal 5 is used for frequency-double-converting the laser of the second wavelength into lasers of a second target wavelength and outputting the same.

[0036] Among them, the pump source 1 is an indispensable part of the laser, which excites the laser medium in the resonant cavity by providing energy to generate laser output. In this embodiment, the pump source 1 can be a laser diode or a single-core semiconductor laser. The single-core semiconductor laser may include a fiber laser, COS, mount packaged chip or 808nm laser. The specific details can be determined according to the actual situation and are not limited here. The first resonant cavity 2 and the second resonant cavity 4 are also an important component of the laser, usually including two or more reflectors to form a stable light wave feedback path. The main function of the first resonant cavity 2 and the second resonant cavity 4 is to enhance the oscillation and amplification of the laser light wave in the resonant cavity, thereby generating a highly monochromatic and coherent laser output. Usually, the front end face of the first resonant cavity 2 is coated with a cavity mirror high-reflection film, and the rear end face is coated with an output film to form a resonant cavity. The output film is used to increase the transmission of the wavelength. In this embodiment, the first resonant cavity 2 is used to absorb the laser generated by the pump source 1 and output the laser of the first wavelength. The first resonant cavity 2 includes a bonded crystal. The bonded crystal includes a crystal combination of neodymium-doped yttrium aluminum garnet (NdYAG) and chromium-doped yttrium aluminum garnet (CrYAG) or a crystal combination of neodymium-doped yttrium vanadate (NdYVO4) and vanadium-doped yttrium aluminum garnet (V:YAG), which can be determined according to actual conditions and is not limited here. The second resonant cavity 4 may include but is not limited to laser media, FP etalons and output mirrors. The end surface coating of the second resonant cavity 4 is used to absorb part of the laser of the first target wavelength and output the laser of the second wavelength. The first frequency doubling crystal 3 and the second frequency doubling crystal 5 are both nonlinear optical materials used to double the laser frequency in the laser. The role of the first frequency doubling crystal 3 and the second frequency doubling crystal 5 in the laser is to increase or change the frequency of the laser, thereby obtaining a higher frequency laser beam. This process is achieved through nonlinear optical effects. When the laser passes through a nonlinear optical medium, the electrons in the medium are affected by the laser electric field, generating new frequency components, and realizing laser output of a new wavelength. In this embodiment, the materials of the first frequency doubling crystal 3 and the second frequency doubling crystal 5 may include but are not limited to nonlinear optical crystals such as lithium triborate (LBO), barium metaborate (BBO) or potassium titanyl phosphate (KTP), and the specific materials may be determined according to actual conditions and are not limited here.

[0037] Specifically, during the detection process of the laser radar, it is necessary to output a dual-wavelength laser to detect the ocean. In this embodiment, the laser generated by the pump source 1 will be sent to the first resonant cavity 2, and the first resonant cavity 2 will pump the laser, absorb the pump light spot and output the laser of the first wavelength. For example, the first wavelength can be 1064nm or 1340nm, which can be determined according to the different target wavelengths output, and no specific restrictions are made here. The laser of the first wavelength output by the first resonant cavity 2 will be sent to the first frequency doubling crystal 3. After receiving the laser of the first wavelength, the first frequency doubling crystal 3 will perform frequency doubling conversion on the laser of the first wavelength, so that the laser of the first wavelength is frequency-doubled and converted to the laser of the first target wavelength, and output through the second resonant cavity 4 and the second frequency doubling crystal 5. For example, the first target wavelength can be 532nm or 670nm, which can be determined according to the first wavelength. When the first wavelength is 1064nm, the corresponding first target wavelength is 532nm, and the laser light with a green wavelength is generated and outputted at this time. When the first wavelength is 1340nm, the corresponding first target wavelength is 670nm, and the laser light with a red wavelength is generated and outputted at this time. After the laser light with the first target wavelength is generated, the second resonant cavity 4 absorbs part of the laser light with the first target wavelength and generates the laser light with a second wavelength. For example, the second wavelength may be 972nm or 960nm. The laser of the second wavelength generated by the second resonant cavity 4 will be sent to the second frequency doubling crystal 5, and the second frequency doubling crystal 5 will perform frequency doubling conversion on the laser of the second wavelength, so that the laser of the second wavelength is frequency-doubled and converted into the laser of the second target wavelength and output. Exemplarily, the second target wavelength can be a blue light wavelength of 480nm or 486nm, which can be specifically determined according to the second wavelength. When the second wavelength is 972nm, the corresponding second target wavelength is 486nm, and when the second wavelength is 960nm, the corresponding second target wavelength is 480nm. In this way, the coaxial output of dual-wavelength laser of the first target wavelength and the second target wavelength is achieved.

[0038] The technical solution of the embodiment of the present invention generates laser through a pump source, and the first resonant cavity, the first frequency doubling crystal, the second resonant cavity and the second frequency doubling crystal are arranged in sequence along the optical axis of the laser, so that the laser generated by the pump source can be sent to the first resonant cavity, the first resonant cavity will pump the laser, absorb the pump light spot and output the laser of the first wavelength to the first frequency doubling crystal, the first frequency doubling crystal will double the frequency of the laser of the first wavelength to the laser of the first target wavelength and output it, one part of the laser of the first target wavelength output will be normally output after passing through the second resonant cavity and the second frequency doubling crystal, and the other part of the laser of the first target wavelength will be absorbed by the second resonant cavity after passing through the second resonant cavity, generating a laser of the second wavelength, and the laser of the second wavelength will be sent to the second frequency doubling crystal, and the second frequency doubling crystal will double the frequency of the laser of the second wavelength to the laser of the second target wavelength and output it. With the above structure, through the coaxial setting, the coaxial output of the dual-wavelength laser is realized, the electro-optical efficiency of the laser is improved, the generation of stray light is reduced, the structure is simple, the cost is low, and the volume of the laser is reduced.

[0039] Optional, Figure 2 The schematic diagram of the structure of the second laser provided by the embodiment of the present invention is shown in FIG. Figure 2 As shown, the laser also includes a shaping mirror group 6; the shaping mirror group 6 is located on the optical axis of the laser and is arranged between the pump source 1 and the first resonant cavity 2; the shaping mirror group 6 is used to shape and focus the laser so that the wavelength of the pump source 1 matches that of the first resonant cavity 2, and outputs laser light of the first wavelength.

[0040] Among them, the role of the shaping mirror group 6 in the laser is mainly to shape the spatial intensity distribution of the laser beam to adapt to different application requirements. The shaping mirror group 6 can change the propagation characteristics of the laser beam, including the shape, size and divergence angle of the laser beam, through specific optical elements, so that the distribution of the laser beam is more uniform or meets specific application requirements. In this embodiment, the shaping mirror group 6 includes one of a single lens, a lens group, an aspherical lens and a light guide cone. The shaping mirror group 6 is used to shape and match the laser emitted by the pump source 1 with the wavelength of the first resonant cavity 2 to ensure that the first resonant cavity 2 can normally output the laser of the first wavelength.

[0041] Optional, Figure 3 The schematic diagram of the structure of the third laser provided by the embodiment of the present invention is shown in FIG. Figure 3As shown, the second resonant cavity 4 includes a laser medium 41, an FP etalon 42 and an output mirror 43; the laser medium 41, the FP etalon 42 and the output mirror 43 are all located on the optical axis of the laser and are sequentially arranged between the first frequency doubling crystal 3 and the second frequency doubling crystal 5; the laser medium 41 is used to absorb part of the laser of the first target wavelength and generate laser of the second wavelength range; the FP etalon 42 is used to narrow the laser line width of the second wavelength range and select the laser of the second wavelength; the output mirror 43 is used to generate and output the laser of the second wavelength.

[0042] Among them, the laser medium 41 is the working material used to generate laser radiation in the laser. Its function is to absorb the laser energy provided by the pump source and generate stimulated radiation under appropriate conditions, thereby amplifying the light beam and generating laser light in the second wavelength range. The laser medium 41 can be a solid, gas, liquid or semiconductor material. In addition, the front end surface of the laser medium 41 will be coated with a high-reflection and high-transmittance film to transmit the laser light of the first target wavelength and reflect the laser light of the remaining wavelengths. The FP etalon 42 is an optical device that works on the principle of multi-beam interference. The FP etalon 42 is usually used to narrow the line width of the laser spectrum in the resonant cavity or to make the laser system run in single mode. By adjusting the cavity length or the temperature of the cavity, the wavelength of the transmitted laser can be accurately controlled, thereby realizing the selection and control of the laser wavelength. In this embodiment, the FP etalon 42 is used to narrow the line width of the laser light in the second wavelength range and select the laser light of the second wavelength. The output mirror 43 is an important component in the second resonant cavity 4. Its main function is to reflect part of the laser energy into the second resonant cavity 4 to maintain the continuous amplification of the laser, while the other part is transmitted out to generate and output the laser light of the second wavelength. The output mirror 43 has a specific reflectivity and transmittance by coating the front end surface. This ratio can be adjusted by changing the material of the output mirror 43 and the coating of the front end surface coating to meet the laser output requirements of different wavelengths.

[0043] Specifically, the first frequency doubling crystal 3 outputs a laser of the first target wavelength to the laser medium 41. The laser medium 41 can absorb part of the laser of the first target wavelength and generate a laser of the second wavelength range. After the laser of the second wavelength range passes through the FP etalon 42, the FP etalon 42 will narrow the laser line width of the second wavelength range, and select a laser of the second wavelength in the second wavelength range. The selected laser of the second wavelength will be sent to the output mirror 43. The output mirror 43 will oscillate the laser of the second wavelength back and forth in the second resonant cavity 4, and lose the lasers of the remaining wavelengths, and finally generate a laser of the second wavelength and output it to the second frequency doubling crystal 5.

[0044] Optional, continue to refer to Figure 3 The material of the laser medium 41 is titanium sapphire, the first wavelength is 1064nm, the first target wavelength is 532nm, and the second wavelength range is 700nm-1000nm.

[0045] Among them, titanium sapphire, also known as titanium-doped sapphire, is an artificial laser crystal made by doping a trace amount of titanium (Ti) element into a sapphire (Al2O3) crystal.

[0046] Specifically, when performing optical detection of the ocean, it is necessary to generate a dual-wavelength laser with a blue-green wavelength. In this embodiment, the material of the laser medium 41 is set to titanium sapphire. At this time, the first wavelength output by the first resonant cavity 2 is 1064nm, and the first frequency doubling crystal 3 converts the 1064nm laser to a green laser with a first target wavelength of 532nm, so that the laser medium 41 can absorb a part of the 532nm laser and generate a second wavelength range of 700nm-1000nm laser. The 700nm-1000nm laser will generate a second wavelength laser after passing through the FP standard 42 and the output mirror 43, and output to the second frequency doubling crystal 5, so that the second frequency doubling crystal 5 generates a blue laser with a second target wavelength.

[0047] Optional, Figure 4 A schematic diagram of the structure of a fourth laser provided in an embodiment of the present invention, referring to Figure 4 As shown, the material of the laser medium 41 is chromium-doped lithium strontium aluminum fluoride laser crystal, the first wavelength is 1340nm, the first target wavelength is 670nm, and the second wavelength range is 770nm-1100nm.

[0048] Among them, chromium-doped lithium strontium aluminum fluoride laser crystal (Cr3+:LiSrAlF6, Cr:LiSAF) is a laser crystal with excellent performance, which has the characteristics of high energy storage and high conversion efficiency and is suitable for ultra-short pulses and ultra-high power lasers.

[0049] Specifically, when performing radar detection on relatively clean ocean water bodies, it is necessary to generate a dual-wavelength laser with red and blue wavelengths. In this embodiment, the material of the laser medium 41 is set to a chromium-doped lithium strontium aluminum fluoride laser crystal. At this time, the first wavelength output by the first resonant cavity 2 is 1340nm, and the first frequency doubling crystal 3 converts the 1340nm laser to a laser with a first target wavelength of 670nm, so that the laser medium 41 can absorb a part of the 670nm red laser and generate a laser with a second wavelength range of 770nm-1100nm. The 770nm-1100nm laser will generate a second wavelength laser after passing through the FP etalon 42 and the output mirror 43, and output to the second frequency doubling crystal 5, so that the second frequency doubling crystal 5 generates a blue laser with a second target wavelength.

[0050] Optional, continue to refer to Figure 3 and Figure 4The front end surface of the output mirror 43 is coated with a high reflection film for reflecting the laser light of the first target wavelength so that the output mirror 43 outputs the laser light of the second wavelength.

[0051] Specifically, when performing laser radar detection on the ocean, detection can also be performed by generating a single blue light band laser. In this embodiment, the laser of the second target wavelength is a blue light laser. When outputting a single blue light band laser, a high-reflection film can be plated on the front end surface of the output mirror 43. When the laser of the first target wavelength is input to the surface of the output mirror 43, the high-reflection film on the end surface of the output mirror 43 will reflect the laser of the first target wavelength, so that the laser of the second wavelength is transmitted and output, so that only the laser of the second target wavelength generated by the 5-fold frequency conversion of the second frequency-doubling crystal, that is, the blue light laser, is finally output for laser radar detection.

[0052] Optional, Figure 5 A schematic diagram of the structure of a fifth laser provided in an embodiment of the present invention, referring to Figure 5 As shown, the laser further includes a filter 7; the filter 7 is located on the optical axis of the laser and is arranged on the side of the second frequency doubling crystal 5 away from the pump source 1, and the filter 7 is used to filter the laser of the first target wavelength to output the laser of the second target wavelength.

[0053] Among them, the filter 7 can selectively transmit lasers within a specific wavelength range and block lasers in other wavelength ranges. In this embodiment, in order to generate lasers of a single blue light band for laser radar detection, a filter 7 can be set on the optical axis of the second frequency doubling crystal 5 away from the pump source 1, so that when the lasers of the first target wavelength and the second target wavelength are sent to the filter 7, the filter 7 can filter the lasers of the first target wavelength and only output the lasers of the second target wavelength, thereby achieving single blue light wavelength laser output.

[0054] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0055] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser, characterized in that: It includes a pump source for generating laser light; and also includes a first resonant cavity, a first frequency doubling crystal, a second resonant cavity and a second frequency doubling crystal which are sequentially arranged along the optical axis of the laser light; The end surface of the first resonant cavity is coated with a film for outputting laser light of a first wavelength; The first frequency doubling crystal is used to frequency-double the laser light of the first wavelength to convert it into laser light of the first target wavelength, and output it through the second resonant cavity and the second frequency doubling crystal; The end surface coating of the second resonant cavity is used to absorb part of the laser light of the first target wavelength, generate laser light of a second wavelength, and output it to the second frequency doubling crystal; The second frequency doubling crystal is used to frequency-double the laser light of the second wavelength to convert the laser light of the second target wavelength and output the laser light.

2. The laser according to claim 1, characterized in that Also includes a reshaping lens set; The shaping mirror group is located on the optical axis of the laser and is arranged between the pump source and the first resonant cavity; the shaping mirror group is used to shape and focus the laser so that the pump source matches the wavelength of the first resonant cavity and outputs the laser of the first wavelength.

3. The laser according to claim 2, characterized in that The shaping lens group includes one of a single lens, a lens group, an aspherical lens and a light guide cone.

4. The laser according to claim 1, characterized in that The second resonant cavity includes a laser medium, an FP etalon and an output mirror; The laser medium, the FP etalon and the output mirror are all located on the optical axis of the laser and are sequentially arranged between the first frequency doubling crystal and the second frequency doubling crystal; The laser medium is used to absorb part of the laser light of the first target wavelength and generate laser light of a second wavelength range; The FP etalon is used to narrow the laser line width in the second wavelength range and select the laser of the second wavelength; The output mirror is used to generate and output laser light of the second wavelength.

5. The laser according to claim 4, characterized in that The material of the laser medium is titanium sapphire, the first wavelength is 1064nm, the first target wavelength is 532nm, and the second wavelength range is 700nm-1000nm.

6. The laser according to claim 4, characterized in that The laser medium is made of chromium-doped lithium strontium aluminum fluoride laser crystal, the first wavelength is 1340 nm, the first target wavelength is 670 nm, and the second wavelength range is 770 nm-1100 nm.

7. The laser according to claim 4, characterized in that The front end surface of the output mirror is coated with a high-reflection film for reflecting the laser light of the first target wavelength so that the output mirror outputs the laser light of the second wavelength.

8. The laser according to claim 1, characterized in that Also includes a filter; The filter is located on the optical axis of the laser and is arranged on the side of the second frequency doubling crystal away from the pump source. The filter is used to filter the laser of the first target wavelength to output the laser of the second target wavelength.

9. The laser according to claim 1, characterized in that The first resonant cavity includes a bonded crystal.

10. The laser according to claim 9, characterized in that The bonded crystal includes a crystal combination of neodymium-doped yttrium aluminum garnet and chromium-doped yttrium aluminum garnet or a crystal combination of neodymium-doped yttrium vanadate and vanadium-doped yttrium aluminum garnet.

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