Solid laser with gain medium with periodic chromium-doped structure

Abstract

The invention provides a solid laser with a periodic chromium-doped structure gain medium. The solid laser comprises a pumping source, a pumping coupling device, a laser resonant cavity input end cavity mirror, a laser gain medium and a laser resonant cavity output coupling mirror which are arranged in sequence, the pumping source is used for emitting pumping light with the wavelength capable of being absorbed by the laser gain medium; the pumping coupling device is used for collimating and focusing the pumping light emitted by the pumping source into the laser gain medium; the laser resonant cavity input end cavity mirror is used for passing through the pump light and reflecting the laser emitted by the laser gain medium; the laser gain medium is a blocky solid gain medium with a chromium-doped structure, and the chromium-doped concentration of the laser gain medium changes periodically; and the laser resonant cavity output coupling mirror is used for partially transmitting the laser emitted by the laser gain medium. The structure with the doping concentration changing periodically in the laser gain medium can effectively relieve the heat effect generated by the gain medium under the excitation of the pump light, so as to realize the stable output of the laser.

Description

Technical Field

[0001] The invention belongs to the technical field of lasers, and in particular relates to a solid laser with a periodic chromium-doped structure gain medium. Background Art

[0002] For solid-state lasers based on bulk crystals, in order to achieve stable and efficient high-power and high-beam quality laser output, thermal management of solid gain media is a key issue. Effective thermal management methods can be used to achieve efficient heat dissipation of the gain medium and uniform heat distribution within the gain medium. In addition to strengthening the effective contact between the gain medium and the heat sink to reduce thermal resistance, designing the configuration of the gain medium itself is also a very effective method. For example, the laser uses a bonded crystal configuration, a thin film crystal configuration, or a slab crystal configuration as the gain medium.

[0003] The bonded crystal configuration refers to bonding two non-doped crystals to the two light-transmitting end faces of a rod-shaped doped crystal, thereby enhancing end face heat dissipation, reducing end face deformation, and reducing the possibility of thermal damage. However, bonded crystals have high requirements for crystal processing and bonding technology, so the manufacturing cost is high. In addition, due to the limitations of the bonding surface, the performance improvement is relatively limited.

[0004] The thin-sheet crystal configuration refers to the length of the gain medium in the light-transmitting direction being much smaller than the width of the light-transmitting surface. Usually, the gain medium thickness is hundreds of microns, while the light-transmitting surface size can reach the centimeter level. Since it uses the light-transmitting surface to dissipate heat, the heat conduction distance is short and the heat dissipation speed is fast. In addition, the pump light size is close to the light-transmitting surface size, so the pump light distribution is very uniform, which can reduce various thermal distortions caused by uneven heat distribution. This type of configuration is suitable for high-power ultrashort pulse lasers, but the thin-sheet configuration is difficult to process and manufacture, and the relevant technology has not yet been fully broken through in China, the cost is high, and the corresponding pump structure is also very complex and bulky.

[0005] The slab crystal configuration means that the gain medium is in the shape of a long strip, with one dimension of the light-transmitting surface being very small, about millimeters, and the other dimension being very large, ranging from centimeters to several centimeters. The light-transmitting length is relatively long, about centimeters. The pump light of the slab configuration is distributed throughout the slab, and the heat is dissipated by the large side surface parallel to the light-transmitting direction. Therefore, it is similar to a thin-sheet structure, with a short heat conduction distance and fast heat dissipation speed, which reduces heat deposition in the medium and can achieve high-power output. The slab structure is also very complex to make, and the biggest problem it faces is that the output laser beam has poor quality, which is more suitable for use in laser amplification rather than laser oscillators.

[0006] It can be seen that the structure for achieving heat dissipation of solid-state lasers based on bulk crystals in the related art has the problems of high implementation difficulty, complex structure and high cost. Summary of the invention

[0007] The technical purpose of the present invention is to provide a solid laser with a periodic chromium-doped structure gain medium, which can effectively alleviate the thermal effect generated by the gain medium under the excitation of pump light to achieve stable laser output.

[0008] To solve the above technical problems, the present invention is implemented as follows: a solid laser with a periodic chromium-doped structure gain medium comprises a pump source, a pump coupling device, a laser resonant cavity input end cavity mirror, a laser gain medium and a laser resonant cavity output coupling mirror arranged in sequence;

[0009] The pump source is used to emit pump light of a wavelength that can be absorbed by the laser gain medium;

[0010] The pump coupling device is used to collimate and focus the pump light emitted by the pump source into the interior of the laser gain medium;

[0011] The laser resonant cavity input end cavity mirror is used to pass the pump light and reflect the laser light emitted by the laser gain medium;

[0012] The laser gain medium is a bulk solid gain medium with a chromium-doped structure, and its chromium-doped concentration varies periodically;

[0013] The laser resonant cavity output coupling mirror is used to partially transmit the laser light emitted by the laser gain medium;

[0014] The cavity mirror at the input end of the laser resonant cavity and the output coupling mirror of the laser resonant cavity form a resonant cavity, which provides positive feedback for laser oscillation and is used to select the wavelength of the generated laser and output the laser.

[0015] Furthermore, the type of the laser gain medium is a II-VI group semiconductor material doped with divalent chromium ions.

[0016] Furthermore, the laser gain medium is chromium-doped zinc selenide crystal Cr:ZnSe;

[0017] Alternatively, the laser gain medium is chromium-doped zinc sulfide crystal Cr:ZnS;

[0018] Alternatively, the laser gain medium is chromium-doped cadmium selenide crystal Cr:CdSe.

[0019] Furthermore, the chromium doping mode of the laser gain medium is that the pump light input end is doped and the output end is undoped;

[0020] Alternatively, the chromium doping of the laser gain medium starts from the non-doping at the pump light input end and ends with the doping at the output end;

[0021] Alternatively, the chromium doping mode of the laser gain medium is doping at both ends and no doping in the middle;

[0022] Alternatively, the chromium doping mode of the laser gain medium is middle doping and no doping at both ends.

[0023] Furthermore, the light-transmitting surface of the laser gain medium is in a shape of square, triangle, ellipse or circle.

[0024] Furthermore, the complete doping period of the laser gain medium is greater than or equal to 2;

[0025] The length period of periodic doping is uniform: within one length period, the length of the doped region is equal to the length of the non-doped region;

[0026] Or the length period of the periodic doping is non-uniform: within a length period, the length of the doped region is not equal to the length of the non-doped region, or the total lengths of different periods are also different.

[0027] Furthermore, the lens types of the laser resonant cavity input end cavity mirror and the laser resonant cavity output coupling mirror are any one of flat-flat, flat-concave, and concave-flat lenses.

[0028] Furthermore, the resonant cavity structure composed of the laser resonant cavity input end cavity mirror and the laser resonant cavity output coupling mirror is any one of an FP cavity, a folded cavity or a ring cavity.

[0029] Furthermore, it also includes a first reflective mirror located between the optical path of the laser gain medium and the laser resonant cavity output coupling mirror, the first reflective mirror is used to reflect the laser output by the laser gain medium to the laser resonant cavity output coupling mirror, wherein the reflectivity of the first reflective mirror to the laser emitted by the laser gain medium is not less than 99%.

[0030] Furthermore, it also includes a first reflective mirror and a second reflective mirror located between the optical path of the laser gain medium and the laser resonant cavity output coupling mirror, the first reflective mirror is used to reflect the laser output by the laser gain medium, the second reflective mirror is used to receive the laser reflected by the first reflective mirror and reflect it to the laser resonant cavity output coupling mirror, and the laser resonant cavity input end cavity mirror is also used to reflect the laser emitted by the laser gain medium to the laser resonant cavity output coupling mirror, wherein the reflectivity of the first reflective mirror and the second reflective mirror to the laser emitted by the laser gain medium is not less than 99%.

[0031] Compared with the prior art, the solid-state laser with a periodic chromium-doped structure gain medium in the present invention has the following beneficial effects:

[0032] The pump light emitted by the pump source is collimated and focused by the pump coupling device to enter the laser gain medium. The laser resonant cavity input end cavity mirror, the laser gain medium and the laser resonant cavity output coupling mirror constitute a resonant cavity. The laser gain medium is a block solid gain medium with a periodic chromium-doped structure, which is used to receive the focused pump light and generate laser under the excitation of the focused pump light, thereby outputting laser in the 2-3μm band. The laser gain medium has a structure with a periodic change in doping concentration, and the doped areas containing chromium ions are alternately arranged with the non-doped areas. The non-doped areas do not absorb the pump light energy and will not actively generate heat. Therefore, as a heat conductive medium, it helps to dissipate the heat of the doped areas, and can effectively alleviate the thermal effect generated by the gain medium under the excitation of the pump light to achieve stable laser output. It has the advantages of low difficulty, simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic diagram of the overall structure of a solid-state laser based on a gain medium having a periodic chromium-doped structure in an embodiment of the present invention;

[0034] Figure 2 It is a structural schematic diagram of a mid-infrared solid laser with a periodic chromium-doped structure gain medium composed of a three-mirror folded cavity in a folded resonant cavity in an embodiment of the present invention;

[0035] Figure 3 It is a structural schematic diagram of a mid-infrared solid laser with a periodic chromium-doped structure gain medium whose resonant cavity is a ring cavity in an embodiment of the present invention;

[0036] Figure 4 It is an alternative to the periodically chromium-doped gain medium in the embodiment of the present invention. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention. All other embodiments obtained by ordinary technicians in the field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0038] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “circumferential”, “radial”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] Combination Figure 1-3 , a solid laser with a periodic chromium-doped structure gain medium is provided, comprising a pump source 1, a pump coupling device 2, a laser resonant cavity input end cavity mirror 3, a laser gain medium 4 and a laser resonant cavity output coupling mirror 5 which are arranged in sequence; the pump source 1 is used to emit pump light of a wavelength that can be absorbed by the laser gain medium 4; the pump coupling device 2 is used to collimate and focus the pump light emitted by the pump source 1 into the laser gain medium 4; the laser resonant cavity input end cavity mirror 3 is used to pass the pump light and reflect the laser emitted by the laser gain medium 4; the laser gain medium 4 is a block solid gain medium with a chromium-doped structure, and its chromium doping concentration varies periodically; the laser resonant cavity output coupling mirror 5 is used to partially transmit the laser emitted by the laser gain medium 4; wherein, the laser resonant cavity input end cavity mirror 3 and the laser resonant cavity output coupling mirror 5 form a resonant cavity, which provides positive feedback for laser oscillation, and is used to select the wavelength of the generated laser and output the laser.

[0041] In this scheme, the pump light emitted by the pump source 1 is collimated and focused by the pump coupling device 2 to enter the interior of the laser gain medium 4. The laser resonant cavity input end cavity mirror 3, the laser gain medium 4 and the laser resonant cavity output coupling mirror 5 constitute a resonant cavity. The laser gain medium 4 is a block solid gain medium with a periodic chromium-doped structure, which is used to receive the focused pump light and generate laser under the excitation of the focused pump light, thereby outputting laser in the 2-3 μm band. The laser gain medium 4 has a structure with a periodic change in doping concentration, that is, the doped area containing chromium ions and the non-doped area are arranged alternately. The non-doped area does not absorb the pump light energy and will not actively generate heat. Therefore, as a heat conductive medium, it helps to dissipate the heat of the doped area, and can effectively alleviate the thermal effect generated by the gain medium under the excitation of the pump light to achieve stable laser output. It has the advantages of low difficulty in implementation, simple structure and low cost.

[0042] Furthermore, the type of laser gain medium 4 is a II-VI semiconductor material doped with divalent chromium ions (Cr2+). The laser gain medium 4 can be a chromium-doped zinc selenide crystal Cr:ZnSe; or, the laser gain medium 4 can be a chromium-doped zinc sulfide crystal Cr:ZnS; or, the laser gain medium 4 can be a chromium-doped cadmium selenide crystal Cr:CdSe. The II-VI semiconductor material doped with divalent chromium ions (Cr2+), represented by Cr:ZnSe / S / CdSe, has the characteristics of no excited state absorption and nearly 100% room temperature fluorescence quantum efficiency. In addition, its ultra-wideband emission spectrum covers the wavelength range from 2 microns to 3 microns, which can support the generation of ultra-short pulses of mid-infrared periodic order and widely tunable lasers. However, since materials such as Cr:ZnSe / S / CdSe have a large refractive index temperature gradient coefficient, high-power pumping will cause a very serious thermal lens effect, which will cause the laser cavity to become unstable and unable to output laser light. In this solution, the structure in which the doping concentration in the laser gain medium 4 changes periodically can effectively alleviate the thermal effect generated by the gain medium under the excitation of pump light.

[0043] Furthermore, the chromium doping mode of the laser gain medium 4 may be to start with doping at the pump light input end and end with undoping at the output end, which is beneficial to increasing pump absorption and increasing efficiency under low-power pumping; or, the chromium doping mode of the laser gain medium 4 may be to start with undoping at the pump light input end and end with doping at the output end, which is helpful to increase the heat dissipation channel in the area with the strongest pump light absorption; or, the chromium doping mode of the laser gain medium 4 may be to dope at both ends and undope in the middle, which is suitable for applying pumping at both ends at the same time; or, the chromium doping mode of the laser gain medium 4 may be to dope in the middle and undope at both ends, which is the method that increases the heat dissipation channel in the doped area the most.

[0044] In some embodiments, in combination Figure 4 The laser gain medium 4 may be provided with a plurality of chromium-doped segments along its length direction, and the portion between adjacent chromium-doped segments is undoped.

[0045] Furthermore, the shape of the light-transmitting surface of the laser gain medium 4 can be square, triangular, elliptical or circular, etc.

[0046] Further, the complete doping period of the laser gain medium 4 is greater than or equal to 2. The length period of the periodic doping is uniform: within one length period, the length of the doped region is equal to the length of the non-doped region; or the length period of the periodic doping is non-uniform: within one length period, the length of the doped region is not equal to the length of the non-doped region, or the total lengths of different periods are also different.

[0047] Furthermore, the lens types of the laser resonant cavity input end cavity mirror 3 and the laser resonant cavity output coupling mirror 5 are any one of flat-flat, flat-concave, and concave-flat lenses.

[0048] Furthermore, the resonant cavity structure composed of the laser resonant cavity input end cavity mirror 3 and the laser resonant cavity output coupling mirror 5 is any one of an FP cavity, a folded cavity or a ring cavity.

[0049] In this scheme, three examples of solid-state lasers with periodic chromium-doped structure gain media are provided, and the specific schemes are as follows:

[0050] Example 1:

[0051] like Figure 1 As shown, in this example, a pump source 1, a pump coupling device 2, a cavity mirror 3 at the input end of a laser resonant cavity, a laser gain medium 4 and a laser resonant cavity output coupling mirror 5 are arranged in sequence along a straight line, and the pump source 1 is used to emit pump light of a wavelength that can be absorbed by the laser gain medium 4; the pump coupling device 2 is used to collimate and focus the pump light emitted by the pump source 1 into the interior of the laser gain medium 4; the cavity mirror 3 at the input end of the laser resonant cavity is used to pass the pump light and reflect the laser emitted by the laser gain medium 4; the laser gain medium 4 is a bulk solid gain medium with a chromium-doped structure, and its chromium-doped concentration varies periodically, which can effectively alleviate the thermal effect generated by the gain medium under the excitation of the pump light; the laser resonant cavity output coupling mirror 5 is used to partially transmit the laser emitted by the laser gain medium 4; wherein, the cavity mirror 3 at the input end of the laser resonant cavity and the laser resonant cavity output coupling mirror 5 form an FP resonant cavity, which provides positive feedback for laser oscillation, and is used to select the wavelength of the generated laser and output the laser.

[0052] Example 2:

[0053] like Figure 2As shown, in this example, compared with Example 1, it also includes a first reflective mirror 6 located between the optical path of the laser gain medium 4 and the laser resonant cavity output coupling mirror 5, and the first reflective mirror 6 is used to reflect the laser output by the laser gain medium 4 to the laser resonant cavity output coupling mirror 5, wherein the reflectivity of the first reflective mirror to the laser emitted by the laser gain medium 4 is not less than 99%.

[0054] Specifically, the pump source 1, the pump coupling device 2, the cavity mirror 3 at the input end of the laser resonator, the laser gain medium 4 and the first reflector 6 are arranged along a straight line, and the laser resonator output coupling mirror 5 is located on the side. Therefore, the cavity mirror 3 at the input end of the laser resonator, the laser gain medium 4, the first reflector 6 and the laser resonator output coupling mirror 5 together constitute a folded resonator. The pump light emitted by the pump source 1 passes through the pump coupling device 2, is collimated and focused by the pump coupling device 2, and then acts on the solid laser gain medium 4 with a periodic chromium-doped structure through the cavity mirror 3 at the input end of the laser resonator. The solid laser gain medium 4 with a periodic chromium-doped structure generates a population inversion under the action of the focused pump light, thereby generating laser light. The generated laser light is oscillated and reflected by the cavity mirror 3 at the input end of the laser resonator, the first reflector 6 and the laser resonator output coupling mirror 5, and then outputted through the laser coupling output mirror. In this folded cavity, the cavity mirror 3 at the input end of the laser resonator and the laser resonator output coupling mirror 5 can pass the laser light provided by the pump source 1 with high transmittance, and can reflect the laser light emitted by the laser gain medium 4 with high reflectivity. The laser gain medium 4 is a block solid gain medium with a periodic chromium-doped structure, which is used to receive the focused pump light and generate laser under the excitation of the focused pump light. Its front and rear end surfaces can pass the pump source 1 and the laser emitted by itself with high transmittance, and this structure with periodic changes in doping concentration can effectively alleviate the thermal effect generated by the gain medium under the excitation of pump light.

[0055] Example 3:

[0056] like Figure 3 As shown, in this example, compared with Example 1, it also includes a first reflecting mirror 6 and a second reflecting mirror 7 located between the optical path of the laser gain medium 4 and the laser resonant cavity output coupling mirror 5, the first reflecting mirror 6 is used to reflect the laser output by the laser gain medium 4, the second reflecting mirror 7 is used to receive the laser reflected by the first reflecting mirror 6 and reflect it to the laser resonant cavity output coupling mirror 5, and the laser resonant cavity input end cavity mirror 3 is also used to reflect the laser emitted by the laser gain medium 4 to the laser resonant cavity output coupling mirror 5, wherein the reflectivity of the first reflecting mirror and the second reflecting mirror to the laser emitted by the laser gain medium 4 is not less than 99%.

[0057] Specifically, the pump source 1, the pump coupling device 2, the laser resonant cavity input end cavity mirror 3, the laser gain medium 4 and the first reflective mirror 6 are arranged along a straight line, and the second reflective mirror 7 and the laser resonant cavity output coupling mirror 5 are located on the side, and the laser resonant cavity input end cavity mirror 3, the laser gain medium 4, the first reflective mirror 6, the second reflective mirror 7 and the laser resonant cavity output coupling mirror 5 together constitute a ring resonant cavity.

[0058] The pump light emitted by the pump source 1 passes through the pump coupling device 2, is collimated and focused by the pump coupling device 2, and then acts on the solid laser gain medium 4 with a periodic chromium-doped structure through the cavity mirror 3 at the input end of the laser resonator. The solid laser gain medium 4 with a periodic chromium-doped structure produces a population inversion under the action of the focused pump light, and then generates laser light. The generated laser light is oscillated and reflected by the cavity mirror 3 at the input end of the laser resonator, the first reflector 6, and the laser resonator output coupling mirror 5, and then outputted through the laser coupling output mirror 7. The characteristics of the cavity mirror 3 at the input end of the laser resonator, the laser resonator output coupling mirror 5, and the second reflector 7 in this ring resonator are that the laser light provided by the pump source 1 can pass through with high transmittance, and the laser light emitted by the laser gain medium 4 can be reflected with high reflectivity. The laser gain medium 4 is characterized by a block solid gain medium with a periodic chromium-doped structure, which is used to receive the focused pump light and generate laser under the excitation of the focused pump light. Its front and rear end surfaces can pass the pump source 1 and the laser emitted by itself with high transmittance, and this structure with periodic changes in doping concentration can effectively alleviate the thermal effect generated by the gain medium under the excitation of pump light.

[0059] 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 spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A solid-state laser having a periodic chromium-doped gain medium, characterized in that: It includes a pump source, a pump coupling device, a laser resonant cavity input end cavity mirror, a laser gain medium and a laser resonant cavity output coupling mirror which are arranged in sequence; The pump source is used to emit pump light of a wavelength that can be absorbed by the laser gain medium; The pump coupling device is used to collimate and focus the pump light emitted by the pump source into the interior of the laser gain medium; The laser resonant cavity input end cavity mirror is used to pass the pump light and reflect the laser light emitted by the laser gain medium; The laser gain medium is a bulk solid gain medium with a chromium-doped structure, and its chromium-doped concentration varies periodically; The laser resonant cavity output coupling mirror is used to partially transmit the laser light emitted by the laser gain medium; The cavity mirror at the input end of the laser resonant cavity and the output coupling mirror of the laser resonant cavity form a resonant cavity, which provides positive feedback for laser oscillation and is used to select the wavelength of the generated laser and output the laser.

2. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 1, characterized in that: The type of the laser gain medium is a II-VI semiconductor material doped with divalent chromium ions.

3. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 2, characterized in that: The laser gain medium is chromium-doped zinc selenide crystal Cr:ZnSe; Alternatively, the laser gain medium is chromium-doped zinc sulfide crystal Cr:ZnS; Alternatively, the laser gain medium is chromium-doped cadmium selenide crystal Cr:CdSe.

4. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 2, characterized in that: The chromium doping mode of the laser gain medium is that the pump light input end is doped and the output end is undoped; Alternatively, the chromium doping of the laser gain medium starts from the non-doping at the pump light input end and ends with the doping at the output end; Alternatively, the chromium doping mode of the laser gain medium is doping at both ends and no doping in the middle; Alternatively, the chromium doping mode of the laser gain medium is middle doping and no doping at both ends.

5. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 1, characterized in that: The shape of the light-transmitting surface of the laser gain medium is square, triangle, ellipse or circle.

6. The solid-state laser having a periodic chromium-doped structure gain medium according to any one of claims 1 to 5, characterized in that: The complete doping period of the laser gain medium is greater than or equal to 2; The length period of periodic doping is uniform: within one length period, the length of the doped region is equal to the length of the non-doped region; Or the length period of the periodic doping is non-uniform: within a length period, the length of the doped region is not equal to the length of the non-doped region, or the total lengths of different periods are also different.

7. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 6, characterized in that: The lens types of the laser resonant cavity input end cavity mirror and the laser resonant cavity output coupling mirror are any one of flat-flat, flat-concave, and concave-flat lenses.

8. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 6, characterized in that: The resonant cavity structure composed of the laser resonant cavity input end cavity mirror and the laser resonant cavity output coupling mirror is any one of an FP cavity, a folded cavity or a ring cavity.

9. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 6, characterized in that: It also includes a first reflective mirror located between the optical path of the laser gain medium and the laser resonant cavity output coupling mirror, the first reflective mirror is used to reflect the laser output by the laser gain medium to the laser resonant cavity output coupling mirror, wherein the reflectivity of the first reflective mirror to the laser emitted by the laser gain medium is not less than 99%.

10. The solid-state laser having a periodic chromium-doped structure gain medium according to claim 6, characterized in that: It also includes a first reflective mirror and a second reflective mirror located between the optical path of the laser gain medium and the laser resonant cavity output coupling mirror, wherein the first reflective mirror is used to reflect the laser output by the laser gain medium, the second reflective mirror is used to receive the laser reflected by the first reflective mirror and reflect it to the laser resonant cavity output coupling mirror, and the laser resonant cavity input end cavity mirror is also used to reflect the laser emitted by the laser gain medium to the laser resonant cavity output coupling mirror, wherein the reflectivity of the first reflective mirror and the second reflective mirror to the laser emitted by the laser gain medium is not less than 99%.

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