Gain medium for 1.5-1.6 [mu] m wave band laser and laser device using gain medium

Abstract

The invention discloses a gain medium for 1.5-1.6 [mu] m wave band laser and a laser device using the gain medium, and belongs to the technical field of laser devices. The Er < 3 + > / Yb < 3 + > double-doped YPO4 crystal has the characteristics of a layered structure and easy cleavage, a wafer obtained by cleavage from a growing blank crystal is directly used as a gain medium, and solid laser output at the wave band of 1.5-1.6 microns is realized by utilizing 975nm wave band semiconductor laser pumping. And a pair of natural cleavage surfaces of the cleavage wafer are respectively used as an input end surface and an output end surface of the laser gain medium. According to the technical scheme, cutting, polishing and other machining processes of the laser gain medium can be omitted, the preparation difficulty and cost of the laser gain medium are greatly reduced, and meanwhile machining defects caused in the cutting and polishing processes of the wafer can be avoided.

Description

Technical Field

[0001] The present application relates to a gain medium for lasers in the 1.5-1.6 μm band and a laser using the gain medium, belonging to the technical field of laser devices. Background Art

[0002] 1.5-1.6μm band laser has the characteristics of high atmospheric transmittance, strong smoke penetration ability, easy detection, low background noise and high eye safety. It can be used as the detection light source of laser rangefinder and laser radar, and is widely used in various civil industries and military fields. 3+ / Yb 3+ Double-doped glass and crystal materials can achieve solid-state laser output in the 1.5-1.6μm band. 3+ / Yb 3+ The process of doubly doped 1.5-1.6μm laser gain medium is generally as follows: according to the specific requirements of pump light and laser device design, the high optical quality Er 3+ / Yb 3+ The double-doped laser material is cut into block or rod-shaped elements with a thickness of several millimeters, and then these elements are polished with high precision and used as gain media in laser experiments. The two light-transmitting surfaces of the polished gain medium should have very high smoothness, flatness and parallelism, so as to reduce the surface loss of the medium and realize the effective operation of the 1.5-1.6μm band laser. The element cutting and polishing process and its processing accuracy greatly increase the difficulty and cost of preparing laser gain media. Summary of the invention

[0003] According to one aspect of the present application, a gain medium for a 1.5-1.6 μm band laser and a laser using the gain medium are provided. 3+ / Yb 3+ The double-doped YPO4 crystal has the characteristics of layered structure and easy cleavage. The wafer obtained by cleaving the grown blank crystal is directly used as the gain medium. The 975nm band semiconductor laser pumping is used to achieve 1.5-1.6μm band solid laser output. A pair of natural cleavage surfaces of the cleaved wafer are used as the input and output end faces of the laser gain medium respectively. This technical solution can eliminate the cutting and polishing of the laser gain medium, greatly reducing the difficulty and cost of preparing the laser gain medium, and can also avoid the processing defects caused by the wafer during the cutting and polishing process.

[0004] This application adopts the following technical solutions:

[0005] A gain medium for a 1.5-1.6 μm band laser, wherein the gain medium is a cleaved wafer;

[0006] The cleaved wafer is made of Er with cleavage characteristics 3+ / Yb 3+ The double-doped crystals were obtained by cleavage.

[0007] This application adopts Er with cleavage characteristics 3+ / Yb 3+ The cleaved wafer obtained from the double-doped crystal is directly used as the laser gain medium, and a pair of natural cleavage planes of the cleaved wafer are directly used as the input and output end faces of the laser gain medium respectively.

[0008] In this application 3+ / Yb 3+ The preparation method and cleavage method of the double-doped crystal are not strictly limited, and those skilled in the art can select from the existing technologies as needed.

[0009] At present, the cleavage characteristics of crystals have been widely used in the processing of wave plates of mica and some semiconductor crystals. Due to the weak bond force between layers, some crystals with layered structures are easy to split into smooth planes parallel to the crystal layers under the action of external forces. This property is called cleavage, and the smooth plane is called the cleavage plane. Since the cleavage of the crystal comes from the result of the ion interaction between its internal layers, the cleavage plane has very high smoothness, flatness and parallelism, reaching or even better than the effect of mechanical processing. This application uses Er 3+ / Yb 3+ The double-doped YPO4 crystal has a layered structure and is easy to cleave. The wafer obtained by cleaving from the grown blank crystal is directly used as a gain medium.

[0010] Optionally, the Er 3+ / Yb 3+ The chemical formula of the double-doped crystal is Er x Yb y Y (1-x-y) PO4, also known as Er 3+ / Yb 3+ Double-doped YPO4 (Er:Yb:YPO4) crystal, wherein x=0.2-3.0at.%, y=2-30at.%.

[0011] The Er described in this application 3+ / Yb 3+ The double-doped crystal is grown by the top seed crystal flux method. The preparation method and process conditions are not strictly limited in this application, and those skilled in the art can choose from existing technologies or commercial sources as needed.

[0012] Optionally, the cleaved wafer is an Er wafer with a (100) cleavage plane. x Yb y Y (1-x-y)PO4 cleavage wafer,

[0013] In the present application, in the Er:Yb:YPO4 crystal, cleavage easily occurs along the (100) crystal plane due to the large lattice spacing between the (100) crystal planes and the weak bond force. The surface of the Er:Yb:YPO4 cleaved wafer obtained by the cleavage method has very high smoothness, flatness and parallelism, and can be directly used as a laser gain medium without further processing.

[0014] Optionally, the Er 3+ / Yb 3+ The double-doped crystal belongs to the tetragonal system with a space group of I41 / amd. 3+ / Yb 3+ A Y in a doped crystal 3+ and eight O 2- Forming a YO8 coordinated polyhedral group, a P 5+ and four O's 2- Forming PO4 tetrahedral groups, YO8 and PO4 groups are connected by shared O 2- interconnected to form a crystal framework; 3+ / Yb 3+ Er in double-doped crystals 3+ and Yb 3+ Partial replacement of Y 3+ , with D 2d The crystal has high thermal conductivity (about 12.0Wm -1 K -1 ), large absorption cross section (3.2×10 -20 cm 2 @975nm), long laser upper level fluorescence lifetime (about 4.2ms) and high Yb 3+ →Er 3+ It has advantages such as energy transfer efficiency (>90%) and is a better laser gain medium in the 1.5~1.6μm band.

[0015] According to another aspect of the present application, a laser using the gain medium is provided, wherein the laser is a 1.5-1.6 μm band solid laser, comprising a pump source and a gain medium;

[0016] The pump source is a semiconductor laser that can generate laser light in the 950nm band or the 975nm band;

[0017] The gain medium is selected from at least one of the gain media of the aforementioned 1.5-1.6 μm band laser;

[0018] The input end face and the output end face of the gain medium are respectively plated with an input dielectric film and an output dielectric film; or,

[0019] The input end face of the gain medium is not coated with an input dielectric film, and the laser further comprises a laser cavity input mirror whose end face is coated with an input dielectric film; or,

[0020] The output end face of the gain medium is not coated with an output dielectric film, and the laser further comprises a laser cavity output mirror whose end face is coated with an output dielectric film; or,

[0021] The input end face and the output end face of the gain medium are not coated with a dielectric film, and the laser further comprises a laser cavity input mirror and a laser cavity output mirror, whose end faces are respectively coated with an input dielectric film and an output dielectric film;

[0022] The laser cavity input mirror is coaxially arranged between the pump source and the gain medium along the laser optical path;

[0023] The laser cavity output mirror is coaxially arranged along the laser optical path on the optical path of the gain medium at a side away from the pump source.

[0024] Optionally, the transmittance of the input dielectric film at a wavelength of 950 or 975 nm is higher than 80%, and the transmittance at a wavelength of 1.5 to 1.6 μm is lower than 0.5%;

[0025] The transmittance of the output dielectric film in the 1.5-1.6 μm band is 0.5%-20%.

[0026] Optionally, the laser is a tunable solid-state laser in the 1.5-1.6 μm band;

[0027] Based on the structure of the aforementioned 1.5-1.6 μm band solid laser, the laser further includes a wavelength tuning element in the 1.5-1.6 μm band;

[0028] When the laser includes a laser cavity output mirror, the wavelength tuning element is coaxially arranged between the gain medium and the laser cavity output mirror along the laser optical path;

[0029] Optionally, the solid laser is a 1.5-1.6 μm band solid pulse laser;

[0030] Based on the structure of the aforementioned 1.5-1.6 μm band solid-state laser, the laser further includes a 1.5-1.6 μm band Q-switching element and / or a mode-locking element;

[0031] When the laser includes a laser cavity output mirror, the Q-switching element and / or the mode-locking element is coaxially arranged between the gain medium and the laser cavity output mirror along the laser optical path;

[0032] When there is no laser cavity output mirror in the laser, the Q-switching element and / or the mode-locking element are coaxially arranged along the laser optical path on the optical path of the gain medium away from the pump source, and the output end surface of the Q-switching element and / or the mode-locking element is plated with an output medium film.

[0033] Optionally, the laser is a frequency-doubled laser in the 1.5-1.6 μm band;

[0034] Based on the structure of the aforementioned 1.5-1.6 μm band solid laser, the laser also includes a 1.5-1.6 μm band frequency doubling crystal;

[0035] When the laser includes a laser cavity output mirror, the frequency doubling crystal is coaxially arranged between the gain medium and the laser cavity output mirror along the laser optical path;

[0036] When there is no laser cavity output mirror in the laser, the frequency doubling crystal is coaxially arranged along the laser optical path on the optical path of the gain medium on the side away from the pump source, and the output end surface of the frequency doubling crystal is plated with an output medium film;

[0037] Optionally, the transmittance of the input dielectric film at 950 or 975 nm is higher than 80%, the transmittance at 1.5 to 1.6 μm is lower than 0.5%, and the transmittance at 0.75 to 0.8 μm is lower than 0.5%;

[0038] The transmittance of the output dielectric film in the 1.5-1.6 μm wave band is lower than 0.5%, and the transmittance in the 0.75-0.8 μm frequency doubling wave band is greater than 70%.

[0039] Optionally, the laser is a frequency-doubled pulse laser in the 1.5-1.6 μm band;

[0040] Based on the structure of the aforementioned 1.5-1.6 μm band solid-state laser, the laser further includes a Q-switching element and / or a mode-locking element, and a frequency-doubling crystal;

[0041] When the laser includes a laser cavity output mirror, the Q-switching element and / or the mode-locking element and the frequency-doubling crystal are coaxially arranged in sequence between the gain medium and the laser cavity output mirror along the laser optical path;

[0042] When there is no laser cavity output mirror in the laser, the Q-switching element and / or the mode-locking element are coaxially arranged between the gain medium and the frequency doubling crystal along the laser optical path, and the output end face of the frequency doubling crystal is plated with an output medium film;

[0043] Optionally, the transmittance of the input dielectric film at 950 or 975 nm is higher than 80%, the transmittance at 1.5 to 1.6 μm is lower than 0.5%, and the transmittance at 0.75 to 0.8 μm is lower than 0.5%;

[0044] The transmittance of the output dielectric film in the 1.5-1.6 μm wave band is lower than 0.5%, and the transmittance in the 0.75-0.8 μm frequency doubling wave band is greater than 70%.

[0045] Optionally, based on the structure of any of the above lasers, the laser further includes a focusing coupling mirror;

[0046] When the laser includes a laser cavity input mirror, the focusing coupling mirror is coaxially arranged between the pump source and the laser cavity input mirror along the laser optical path;

[0047] When there is no laser cavity input mirror in the laser, the focusing coupling mirror is coaxially arranged between the pump source and the gain medium along the laser optical path.

[0048] In the present application, the focusing coupling mirror is used to focus the output light of the pump source on the gain medium. The gain medium is placed near the focus point of the pump light and does not exceed the Rayleigh length range of the output light beam of the pump source.

[0049] The beneficial effects of this application include:

[0050] This application utilizes the cleavage characteristics of Er:Yb:YPO4 crystals and uses Er:Yb:YPO4 cleaved wafers as the gain medium for 1.5-1.6μm lasers. The surface of Er:Yb:YPO4 cleaved wafers has very high smoothness, flatness, and parallelism, and can be directly used as laser gain media without further processing. It can eliminate the cutting and polishing processes required for conventional laser gain media, greatly reducing the difficulty and cost of preparing laser gain media, and can also avoid processing defects caused by wafer cutting and polishing. Er:Yb:YPO4 crystals have high thermal conductivity (about 12.0Wm -1 K -1 ), large absorption cross section (3.2×10 -20 cm 2 @975nm), long laser upper level fluorescence lifetime (about 4.2ms) and high Yb 3+ →Er 3+ Energy transfer efficiency (> 90%) and other advantages. Using this crystal as a laser gain medium can effectively reduce the thermal effect of the crystal and achieve high-power, high-efficiency continuous and high-energy, high-repetition-rate pulsed 1.5-1.6μm band solid laser operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of the structure of the 1.5-1.6 μm band solid-state laser of this application.

[0052] Figure 2 This is a schematic diagram of the structure of the 1.5-1.6 μm band solid pulse laser of this application.

[0053] Figure 3 This is a schematic diagram of the structure of the 1.5-1.6 μm band tunable solid-state laser of this application.

[0054] Figure 4 This is a schematic diagram of the structure of the 1.5-1.6 μm band frequency-doubled laser of the present application.

[0055] In the attached figure, the black line with an arrow represents the direction of the laser light path. DETAILED DESCRIPTION

[0056] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0057] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0058] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0059] Example 1 Gain Medium for Lasers in the 1.5-1.6 μm Band

[0060] Growing 0.5at.% Er-doped nanoparticles by top seed flux method 3+ and 5.0at.%Yb 3+ YPO4 laser crystal. A 7×3mm cross-section piece was obtained by cleaving the grown blank crystal using mechanical stress method. 2 And a (100) cleaved wafer with a thickness of 1.4 mm, i.e., a (0.5 at.%) Er:(5.0 at.%) Yb:YPO4 cleaved wafer.

[0061] The absorption coefficient of the chip at 975.4nm pump wavelength is 8.9cm -1 , which can absorb about 70% of the incident pump power in a single pass.

[0062] The cleaved wafer can be directly used as a laser gain medium without the need for processes such as cutting, polishing and anti-reflection coating.

[0063] Example 2 1.5-1.6 μm band solid-state laser

[0064] The schematic diagram of the structure of the 1.5-1.6μm band solid-state laser is shown in Figure 1 As shown, a pump source, a focusing coupling mirror, a laser cavity input mirror, a gain medium and a laser cavity output mirror are coaxially arranged in sequence along the laser optical path, wherein:

[0065] Gain medium: The (0.5at.%) Er:(5.0at.%) Yb:YPO4 cleaved wafer of Example 1 is used as the gain medium. The gain medium is fixed on a copper groove with a light hole in the middle. The pump beam is focused on the cleaved wafer after passing through a focusing coupling mirror. The waist spot diameter of the pump beam on the wafer is about 100μm. The copper groove is cooled by 20℃ circulating water and placed in the laser cavity.

[0066] Pump source: A fiber-coupled semiconductor laser with an output wavelength of 975.4 nm and a fiber core diameter of 100 μm;

[0067] Laser cavity input mirror: A plane mirror is placed between the focusing coupling mirror and the cleaved wafer and as close to the cleaved wafer as possible. The end face of the laser cavity input mirror is coated with an input dielectric film, with a transmittance of T = 90% at a wavelength of 975.4nm and a transmittance of T = 0.2% at a wavelength of 1.5-1.6μm.

[0068] Laser cavity output mirror: A plano-concave mirror with a curvature radius of 100 mm is used, which is placed behind the cleaved wafer and about 100 mm away from the input mirror. The end face of the laser cavity output mirror is coated with an output dielectric film, and the transmittance T=3.0% in the 1.5-1.6μm band;

[0069] By using the above laser structure and utilizing a 4.75W 975.4nm semiconductor laser end-pumping the gain medium, a 1587nm solid continuous laser output with a continuous power of 1.12W can be obtained.

[0070] In this example, the dielectric film on the laser cavity input mirror and the laser cavity output mirror can also be plated on the input end face and the output end face of the gain medium, thereby omitting the corresponding laser cavity input mirror and / or laser cavity output mirror, and the function is the same)

[0071] Example 3 1.5-1.6 μm band solid pulse laser

[0072] The schematic diagram of the structure of the 1.5-1.6μm band solid pulse laser is shown in Figure 2 As shown, based on the laser structure of Example 2, a passive Q-switching element is also included, which is placed between the cleaved wafer and the laser cavity output mirror and as close to the cleaved wafer as possible; the passive Q-switching element adopts Co with a thickness of 1.1 mm and an initial transmittance of 96%. 2+ :MgAl2O4 crystal, both end faces of the crystal are coated with an anti-reflection film in the 1.5-1.6μm band.

[0073] Using the above-mentioned solid pulse laser structure, a 1538nm passively Q-switched pulse laser output with an energy of 19.2μJ, a repetition frequency of 13.0kHz, a pulse width of 56ns and a peak output power of 0.34kW can be obtained by end-pumping the cleaved wafer with a 4.75W 975.4nm semiconductor laser.

[0074] In this example, the dielectric film on the laser cavity input mirror and the laser cavity output mirror can also be selected to correspond to the input end face and Co plated on the gain medium. 2+ :On the output end face of the MgAl2O4 crystal, the corresponding laser cavity input mirror and / or laser cavity output mirror are omitted, and the function is the same, and passive Q-switched pulse laser output can also be achieved.

[0075] Example 4 1.5-1.6 μm band tunable solid-state laser

[0076] The schematic diagram of the structure of the 1.5-1.6μm band tunable solid-state laser is shown in Figure 3 As shown, based on the laser structure of Example 2, it also includes a wavelength tuning element, which is placed between the cleaved wafer and the laser cavity output mirror at the Brewster angle and as close to the cleaved wafer as possible; the wavelength tuning element adopts a SiO2 birefringent filter with a thickness of 2.0 mm and both end faces coated with a 1.5-1.6 μm band anti-reflection film.

[0077] By using the above tunable laser structure and end-pumping the cleaved wafer with a 4.75W 975.4nm semiconductor laser, a tunable continuous laser output in the 1.5-1.6μm band with an output power higher than 100mW can be obtained.

[0078] Example 5 1.5-1.6 μm frequency-doubled laser

[0079] The schematic diagram of the structure of the 1.5-1.6μm band frequency-doubled laser is shown in the figure below. Figure 4 As shown, based on the laser structure of Example 2, a frequency doubling crystal is further included, which is cut according to the phase matching angle and placed between the cleaved wafer and the laser cavity output mirror in Example 1; the frequency doubling crystal adopts a nonlinear optical crystal (such as KTP, LBO, β-BBO, etc.) with a frequency doubling wavelength of 1587nm. In addition, the transmittance of the input dielectric film at a wavelength of 975.4nm is T=90%, the transmittance at the 1.5-1.6μm band and the 0.75-0.8μm band is T=0.2%, the transmittance of the output dielectric film at the 1.5-1.6μm band is T=0.2%, and the transmittance at the 0.75-0.8μm frequency doubling band is T=80%.

[0080] By using the frequency-doubled laser structure and end-pumping the cleaved wafer with a 975.4nm semiconductor laser, a 794nm frequency-doubled solid laser output can be obtained.

[0081] Example 6

[0082] Growing 1.0at.% Er-doped nanoparticles by top seed flux method 3+ and 15.0at.%Yb 3+ YPO4 laser crystal. A 6×3mm cross-section piece was obtained by cleaving the grown blank crystal using mechanical stress method. 2 And a (100) cleaved wafer with a thickness of 1.0 mm, that is, a (1.0 at.%) Er:(15.0 at.%) Yb:YPO4 cleaved wafer.

[0083] The absorption coefficient of the chip at a pump wavelength of 975.4 nm is 27 cm -1 , which can absorb about 93% of the incident pump power in a single pass.

[0084] The cleaved wafer can be directly used as a laser gain medium without the need for processes such as cutting, polishing and anti-reflection coating.

[0085] Embodiments 7 to 10

[0086] The gain media in the lasers of Examples 2 to 5 were replaced with the (1.0 at.%) Er:(15.0 at.%) Yb:YPO4 cleaved wafer in Example 6, and the laser output results were similar to those before the replacement.

[0087] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A gain medium for a 1.5-1.6 μm band laser, characterized in that: The gain medium is a cleaved wafer; The cleaved wafer is made of Er with cleavage characteristics 3+ / Yb 3+ The double-doped crystals were obtained by cleavage.

2. The gain medium of the 1.5-1.6 μm band laser according to claim 1, characterized in that: The Er 3+ / Yb 3+ The chemical formula of the double-doped crystal is Er x Yb y Y (1-x-y) PO4; Among them, x=0.2~3.0at.%, y=2~30at.%.

3. The gain medium of the 1.5-1.6 μm band laser according to claim 2, characterized in that: The cleaved wafer is Er with (100) cleavage plane. x Yb y Y (1-x-y) PO4 cleavage wafer.

4. The gain medium of the 1.5-1.6 μm band laser according to claim 2, characterized in that: The Er 3+ / Yb 3+ The double-doped crystals belong to the tetragonal system with the space group of I41 / amd.

5. A laser, characterized in that: Including pump source and gain medium; The pump source is a semiconductor laser that can generate laser light in the 950nm band or the 975nm band; The gain medium is selected from at least one of the gain media of the 1.5-1.6 μm band laser according to claims 1 to 4; The input end face and the output end face of the gain medium are respectively plated with an input dielectric film and an output dielectric film; or, The input end face of the gain medium is not coated with an input dielectric film, and the laser further comprises a laser cavity input mirror whose end face is coated with an input dielectric film; or, The output end face of the gain medium is not coated with an output dielectric film, and the laser further comprises a laser cavity output mirror whose end face is coated with an output dielectric film; or, The input end face and the output end face of the gain medium are not coated with a dielectric film, and the laser further comprises a laser cavity input mirror and a laser cavity output mirror, whose end faces are respectively coated with an input dielectric film and an output dielectric film; The laser cavity input mirror is coaxially arranged between the pump source and the gain medium along the laser optical path; The laser cavity output mirror is coaxially arranged along the laser optical path on the optical path of the gain medium at a side away from the pump source; Preferably, the transmittance of the input dielectric film at 950 or 975 nm is higher than 80%, and the transmittance at 1.5 to 1.6 μm is lower than 0.5%; The transmittance of the output dielectric film in the 1.5-1.6 μm band is 0.5%-20%.

6. The solid-state laser according to claim 5, characterized in that: The laser is a tunable solid laser in the 1.5-1.6 μm band; The laser also includes a wavelength tuning element in the 1.5-1.6 μm band; When the laser includes a laser cavity output mirror, the wavelength tuning element is coaxially arranged between the gain medium and the laser cavity output mirror along the laser optical path.

7. The solid-state laser according to claim 5, characterized in that: The solid laser is a 1.5-1.6 μm band solid pulse laser; The laser also includes a Q-switching element and / or a mode-locking element in the 1.5-1.6 μm band; When the laser includes a laser cavity output mirror, the Q-switching element and / or the mode-locking element is coaxially arranged between the gain medium and the laser cavity output mirror along the laser optical path; When there is no laser cavity output mirror in the laser, the Q-switching element and / or the mode-locking element are coaxially arranged along the laser optical path on the optical path of the gain medium away from the pump source, and the output end surface of the Q-switching element and / or the mode-locking element is plated with an output medium film.

8. The solid-state laser according to claim 5, characterized in that: The laser is a frequency-doubled laser in the 1.5-1.6 μm band; The laser also includes a frequency doubling crystal in the 1.5-1.6 μm band; When the laser includes a laser cavity output mirror, the frequency doubling crystal is coaxially arranged between the gain medium and the laser cavity output mirror along the laser optical path; When there is no laser cavity output mirror in the laser, the frequency doubling crystal is coaxially arranged along the laser optical path on the optical path of the gain medium on the side away from the pump source, and the output end surface of the frequency doubling crystal is plated with an output medium film; Preferably, the transmittance of the input dielectric film at 950 or 975 nm is higher than 80%, the transmittance at 1.5 to 1.6 μm is lower than 0.5%, and the transmittance at 0.75 to 0.8 μm is lower than 0.5%; The transmittance of the output dielectric film in the 1.5-1.6 μm wave band is lower than 0.5%, and the transmittance in the 0.75-0.8 μm frequency doubling wave band is greater than 70%.

9. The solid-state laser according to claim 5, characterized in that: The laser is a frequency-doubled pulse laser in the 1.5-1.6 μm band; The laser also includes a Q-switching element and / or a mode-locking element, and a frequency-doubling crystal; When the laser includes a laser cavity output mirror, the Q-switching element and / or the mode-locking element and the frequency-doubling crystal are coaxially arranged in sequence between the gain medium and the laser cavity output mirror along the laser optical path; When there is no laser cavity output mirror in the laser, the Q-switching element and / or the mode-locking element are coaxially arranged between the gain medium and the frequency doubling crystal along the laser optical path, and the output end face of the frequency doubling crystal is plated with an output medium film; Preferably, the transmittance of the input dielectric film at 950 or 975 nm is higher than 80%, the transmittance at 1.5 to 1.6 μm is lower than 0.5%, and the transmittance at 0.75 to 0.8 μm is lower than 0.5%; The transmittance of the output dielectric film in the 1.5-1.6 μm wave band is lower than 0.5%, and the transmittance in the 0.75-0.8 μm frequency doubling wave band is greater than 70%.

10. The solid-state laser according to any one of claims 5 to 9, characterized in that: The laser also includes a focusing coupling mirror; When the laser includes a laser cavity input mirror, the focusing coupling mirror is coaxially arranged between the pump source and the laser cavity input mirror along the laser optical path; When there is no laser cavity input mirror in the laser, the focusing coupling mirror is coaxially arranged between the pump source and the gain medium along the laser optical path.

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