Monoblock single-frequency solid laser based on volume grating

Abstract

The utility model provides a volume grating-based single-block single-frequency solid-state laser. The volume grating-based single-block single-frequency solid-state laser comprises a pumping source, a pumping light coupling device, a dichroscope, a laser lens and a laser oscillation gain module which are sequentially arranged along the direction of a light path, the pumping source is used for emitting laser with wavelength which can be absorbed by the laser lens; the pump light coupling device is used for focusing laser emitted by the pump source and enabling the laser to enter the laser lens through the dichroscope; the dichroscope is used for transmitting the laser emitted by the pumping source and is also used for reflecting the laser emitted by the laser oscillation gain module; the laser lens is used for partially penetrating laser emitted by the laser oscillation gain module; the laser oscillation gain module comprises a rare earth ion-doped crystal inscribed with a Bragg grating with a uniform period, and the Bragg grating has a frequency selection function. Single-frequency laser oscillation with a large mode field area is achieved, and the problems that a single-frequency laser constructed by discrete components is large in size and poor in stability and a single-block single-frequency laser is low in output power are solved.

Description

Technical Field

[0001] The utility model belongs to the field of laser devices, and particularly relates to a single-block single-frequency solid-state laser based on a volume grating. Background Art

[0002] A single-frequency laser, also known as a single-longitudinal-mode laser, has only a single longitudinal mode oscillating inside its resonant cavity, so only a single longitudinal mode is output outside the cavity. Currently, the main principles and technical methods for realizing single-frequency laser output in solid-state lasers based on single-crystal gain media are as follows:

[0003] The first category is the short-cavity method based on a large longitudinal-mode interval. The advantage of an all-solid-state single-frequency laser composed of the short-cavity method is that the crystal thickness is in the order of hundreds of micrometers, so it has a small volume, stable structure, and is convenient for mass production. However, since the thin laser crystal thickness affects the pump absorption efficiency, it is only possible to improve the doping concentration to increase the power potential, which is very limited. When operating at high power, multiple longitudinal modes are likely to occur, and it is not suitable for lasers with high-power output. The output power is only in the order of hundreds of mW.

[0004] The second category is based on the principle of longitudinal-mode loss tuning and frequency selection. The main methods are as follows: the birefringent filter method. The birefringent filter technology has a simple structure and introduces little loss, but its birefringence ability is limited, and the effect of realizing single frequency is not ideal; the coupled-cavity method. The coupled-cavity mode selection has the advantages of simple structure, low cost, low insertion loss, and high efficiency. However, the coupled-cavity adjustment is difficult, and the requirement for the stability of the cavity is relatively high, so it is not suitable for application in high-power lasers either; the grating frequency-selection method. Using grating frequency selection to obtain single frequency, in a crystal medium laser, a volume holographic grating (VHG) can be used, which can achieve high-power output, but the devices are discrete, resulting in a large volume of the laser; the method of inserting an etalon. The etalon has the functions of frequency selection and tuning. After the etalon selects the frequency, the linewidth is relatively wide. Therefore, in practical applications, it is combined with other methods (such as the ring-cavity method) to achieve single-frequency output.

[0005] The third category is based on the principle of eliminating the standing-wave distribution to eliminate the spatial hole-burning effect. The main ones are the unidirectional ring-cavity method: one type is a non-planar ring cavity constructed by using a single crystal, and the other type is a ring cavity composed of discrete elements; the single-block non-planar ring cavity (NPRO) has excellent stability, good beam quality, and also has the excellent narrow-linewidth single-frequency characteristics of a ring cavity. However, its processing technology requirements are high, the cost is expensive, the wavelength adjustment range is limited, and its output power can only reach the W level; the discrete-element ring-cavity method has stable output and can obtain high-power single-frequency laser output, and the output power can reach dozens of W. However, it uses more discrete optical elements and generally has a large volume.

[0006] In addition, there is also the method of twisting the film cavity: mainly by inserting a wave plate and a polarizer in the cavity to make two light waves propagating in opposite directions have mutually perpendicular polarization states, thereby eliminating the standing wave distribution of the light field in the gain medium, and thus obtaining single-frequency output. The method of twisting the film cavity is applicable to isotropic gain media. In addition, when the pump power is high or the thermal effect is more serious, the depolarization effect of the laser crystal has a greater impact on this. Therefore, the method of twisting the film cavity is applicable to low-power and low-thermal-effect situations.

[0007] Among the above-mentioned solid-state lasers for realizing single-frequency output, they can be further divided into single-frequency lasers that use discrete components to construct a laser resonator. Such lasers have a large volume and poor stability; and single-frequency lasers that use a single crystal to construct a laser resonator, such as short cavities and single-piece non-planar ring cavities. Such lasers have a small volume, good stability but low output power. Utility Model Content

[0008] The technical object of the present utility model is to provide a single-piece single-frequency solid-state laser based on a volume grating, which realizes frequency selection by directly writing a Bragg grating structure with a uniform period inside a single crystal, constructs a single-piece laser resonator single-frequency laser, realizes single-frequency laser oscillation with a large mode field area, and solves the problems of large volume, poor stability of single-frequency lasers constructed by discrete components, and low output power of single-piece single-frequency lasers.

[0009] To solve the above technical problems, the present utility model is realized as follows: providing a single-piece single-frequency solid-state laser based on a volume grating, including a pump source, a pump light coupling device, a dichroic mirror, a laser lens, and a laser oscillation gain module arranged in sequence along the optical path direction;

[0010] The pump source is used to emit laser with a wavelength that can be absorbed by the laser lens;

[0011] The pump light coupling device is used to focus the laser emitted by the pump source and enter the laser lens through the dichroic mirror;

[0012] The dichroic mirror is used to transmit the laser emitted by the pump source and also used to reflect the laser emitted by the laser oscillation gain module;

[0013] The laser lens is used to partially transmit the laser emitted by the laser oscillation gain module;

[0014] The laser oscillation gain module includes a rare-earth ion-doped crystal inscribed with a Bragg grating with a uniform period, and the Bragg grating has a frequency selection function.

[0015] Furthermore, the rare-earth ion-doped crystal includes a rare-earth ion-doped region and / or a non-rare-earth ion-doped region in the optical path direction;

[0016] The Bragg grating is inscribed in the rare-earth ion-doped region; and / or, the Bragg grating is inscribed in the rare-earth ion-undoped region.

[0017] Further, the Bragg grating satisfies the following conditions:

[0018] Λ = -mλ / 2, where m = 1, 2, 3......

[0019] Wherein, Λ is the grating period and λ is the frequency-selective wavelength.

[0020] Further, the rare-earth ions include: neodymium ions, ytterbium ions, thulium ions or holmium ions.

[0021] Further, the transmittance of the dichroic mirror to the laser provided by the pump source is greater than 50%, and the reflectivity to the laser wavelength emitted by the laser oscillation gain module is greater than 50%.

[0022] Further, the transmittance of the laser lens to the laser emitted by the laser oscillation gain module is 1% - 50%.

[0023] Further, the laser lens is replaced by a coating deposited on one side of the laser oscillation gain module close to the dichroic mirror. The coating has a partial transmittance to the laser emitted by the Bragg grating, and the coating and the Bragg grating form a resonant cavity.

[0024] Further, the transmittance of the coating to the laser emitted by the Bragg grating is 1% - 50%.

[0025] Compared with the prior art, the single-piece single-frequency solid-state laser based on a volume grating in the present invention has the beneficial effects that:

[0026] The pump source can emit laser with a wavelength that can be absorbed by the laser lens. Then, the laser is focused by the pump light coupling device and enters the laser lens through the dichroic mirror, and then enters the laser oscillation gain module of the rare-earth ion-doped crystal including the Bragg grating with a uniform period inscribed thereon. The laser oscillation gain module generates laser under the excitation of the focused laser. The generated laser is reflected and output by the dichroic mirror. Among them, the laser oscillation gain module and the laser lens form a resonant cavity for laser oscillation. By directly inscribing a Bragg grating structure with a uniform period inside a single crystal to achieve frequency selection and constructing a single-frequency laser with a single-piece laser resonant cavity, single-frequency laser oscillation with a large mode field area is realized, solving the problems of large volume, poor stability of the single-frequency laser constructed by discrete components, and low output power of the single-piece single-frequency laser. Description of the Drawings

[0027] Figure 1It is a schematic structural layout diagram of a single-frequency solid-state laser based on a volume grating in Example 1 of the embodiments of the present invention;

[0028] Figure 2 It is a schematic structural layout diagram of a single-frequency solid-state laser based on a volume grating in Example 2 of the embodiments of the present invention;

[0029] Figure 3 It is a schematic structural layout diagram of a single-frequency solid-state laser based on a volume grating in Example 3 of the embodiments of the present invention;

[0030] Figure 4 It is a schematic structural layout diagram of a single-frequency solid-state laser based on a volume grating in Example 4 of the embodiments of the present invention;

[0031] Figure 5 It is a schematic structural layout diagram of a single-frequency solid-state laser based on a volume grating in Example 5 of the embodiments of the present invention;

[0032] Figure 6 It is a schematic structural layout diagram of a single-frequency solid-state laser based on a volume grating in Example 6 of the embodiments of the present invention. Detailed implementation manners

[0033] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "circumferential", "radial", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They 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 construed as limiting the present invention.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, "a plurality of" means two or more, unless otherwise specifically defined.

[0036] In the present application, in combination with Figure 1-6 , a single-frequency solid-state laser based on a volume grating is provided, which includes a pump source 1, a pump light coupling device 2, a dichroic mirror 3, a laser lens 4, and a laser oscillation gain module 5 arranged in sequence along the optical path direction; the pump source 1 is used to emit laser light with a wavelength that can be absorbed by the laser lens 4; the pump light coupling device 2 is used to focus the laser light emitted by the pump source 1 through the dichroic mirror 3 and into the laser lens 4; the dichroic mirror 3 is used to transmit the laser light emitted by the pump source 1 and also to reflect the laser light emitted by the laser oscillation gain module 5; the laser lens 4 is used to partially transmit the laser light emitted by the laser oscillation gain module 5; the laser oscillation gain module 5 includes a rare-earth ion-doped crystal inscribed with a Bragg grating having a uniform period, and the Bragg grating has a frequency selection function.

[0037] The pump source 1 can emit laser light with a wavelength that can be absorbed by the laser lens 4. Then, the laser light passes through the pump light coupling device 2 and is focused, then passes through the dichroic mirror 3 and enters the laser lens 4, and then enters the laser oscillation gain module 5 including a rare-earth ion-doped crystal inscribed with a Bragg grating having a uniform period. The laser oscillation gain module 5 generates laser light under the excitation of the focused laser light, and the generated laser light is reflected and output by the dichroic mirror 3. Among them, the laser oscillation gain module 5 and the laser lens 4 form a resonant cavity (the resonant cavity can be a plane-plane cavity, a plane-concave cavity, or a plane-convex cavity) for laser oscillation. By directly inscribing a Bragg grating structure with a uniform period inside a single crystal to achieve frequency selection and constructing a single-frequency laser with a single-block laser resonant cavity, single-frequency laser oscillation with a large mode field area is realized, and the problems of large volume, poor stability of single-frequency lasers constructed by discrete components, and low output power of single-block single-frequency lasers are solved.

[0038] Further, the rare-earth ion-doped crystal includes a rare-earth ion-doped region and / or an undoped rare-earth ion region in the optical path direction; the Bragg grating is inscribed in the rare-earth ion-doped region; and / or, the Bragg grating is inscribed in the undoped rare-earth ion region. The Bragg grating satisfies the following conditions:

[0039] Λ = -mλ / 2 m = 1, 2, 3......

[0040] Where Λ is the grating period and λ is the frequency selection wavelength.

[0041] The rare earth ions include neodymium ions, ytterbium ions, thulium ions, holmium ions, praseodymium ions, etc. The rare earth ions provide population inversion, and the Bragg grating that meets the above conditions provides high reflectivity for the emission wavelength of the corresponding ions, thereby forming single-frequency laser oscillation.

[0042] Specifically, the rare earth ion-doped crystal may only have a rare earth ion-doped region. At this time, the Bragg grating can be inscribed at one end of the rare earth ion-doped crystal far from the laser lens 4; or, the rare earth ion-doped crystal may include a rare earth ion-doped region close to the laser lens 4 and an undoped rare earth ion region at one end of the rare earth ion-doped region far from the laser lens 4. At this time, the Bragg grating can be completely inscribed in the undoped rare earth ion region. Optionally, the Bragg grating can also be partially inscribed in the rare earth ion-doped region and partially inscribed in the undoped rare earth ion region. The Bragg grating has a frequency selection function and can construct a single-frequency laser of a single-block laser resonator, realizing single-frequency laser oscillation with a large mode field area. Among them, when the Bragg grating is inscribed in the undoped rare earth ion region, with the same length of the rare earth ion-doped region, the effective cavity length of the resonator can be increased, and the optical-optical conversion efficiency can be improved.

[0043] Furthermore, the transmittance of the dichroic mirror 3 to the laser provided by the pump source 1 is greater than 50%, and the reflectivity to the laser wavelength emitted by the laser oscillation gain module 5 is greater than 50%.

[0044] Furthermore, the transmittance of the laser lens 4 to the laser emitted by the laser oscillation gain module 5 is 1% - 50%.

[0045] In some embodiments, the laser lens 4 can be replaced by a coating deposited on one side of the laser oscillation gain module 5 close to the dichroic mirror 3. The coating has a partial transmittance to the laser emitted by the Bragg grating, and the coating and the Bragg grating form a resonator. Preferably, the transmittance of the coating to the laser emitted by the Bragg grating is 1% - 50%. Replacing the laser lens 4 with a coating to form a resonator can further reduce the volume of the single-frequency solid-state laser.

[0046] The following are some specific implementation examples. It should be understood that the following solutions are only some specific implementations under the concept of this application and do not limit the protection scope of this application. The solutions adjusted or replaced by those skilled in the art after knowing the concept of this application still fall within the protection scope of this application.

[0047] Example 1:

[0048] Such as Figure 1As shown in the figure, the pump source 1, the pump light coupling device 2, the dichroic mirror 3, the laser lens 4, and the laser oscillation gain module 5 are arranged in a straight line. The angle between the mirror surface of the dichroic mirror 3 and the optical path direction can be 30° - 60°, preferably 45°. The laser oscillation gain module 5 uses a rare-earth ion-doped crystal. The rare-earth ion-doped crystal has only a rare-earth ion-doped region. The Bragg grating is inscribed at one end of the rare-earth ion-doped crystal away from the laser lens 4. The Bragg grating and the laser lens 4 form a resonant cavity, and the resonant cavity is a plane-plane cavity. The laser emitted by the pump source 1 is a semiconductor laser. The transmittance of the dichroic mirror 3 to the laser provided by the pump source 1 is 98%, and the reflectivity to the laser wavelength emitted by the laser oscillation gain module 5 is 98%. The transmittance of the laser lens 4 to the laser emitted by the laser oscillation gain module 5 is 1% - 50%, preferably 10%.

[0049] Example 2:

[0050] As Figure 2 shown in the figure, the pump source 1, the pump light coupling device 2, the dichroic mirror 3, the laser lens 4, and the laser oscillation gain module 6 are arranged in a straight line. The angle between the mirror surface of the dichroic mirror 3 and the optical path direction is 45°. The laser oscillation gain module 6 uses a rare-earth ion-doped crystal. The rare-earth ion-doped crystal has a rare-earth ion-doped region near the laser lens 4 and an undoped rare-earth ion region at one end of the rare-earth ion-doped region away from the laser lens 4. Therefore, the Bragg grating is completely inscribed in the undoped rare-earth ion region. The Bragg grating and the laser lens 4 form a resonant cavity, and the resonant cavity is a plane-plane cavity. Compared with Example 1, when the length of the rare-earth ion-doped region in the crystal is the same, the effective cavity length can be increased, and the optical-optical conversion efficiency can be improved. The laser emitted by the pump source 1 is a semiconductor laser. The transmittance of the dichroic mirror 3 to the laser provided by the pump source 1 is 98%, and the reflectivity to the laser wavelength emitted by the laser oscillation gain module 6 is 98%. The transmittance of the laser lens 4 to the laser emitted by the laser oscillation gain module 6 is 1% - 50%, preferably 10%.

[0051] Example 3:

[0052] As Figure 3As shown, the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 are arranged in a straight line. The dichroic mirror 3, the laser lens 4, and the laser oscillation gain module 5 are arranged in a straight line. The angle between the mirror surface of the dichroic mirror 3 and the optical path direction is 45°. That is, the straight-line arrangement direction of the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 and the straight-line arrangement direction of the dichroic mirror 3, the laser lens 4, and the laser oscillation gain module 5 form a 90° angle. The pump source 1, the pump light coupling device 2, the laser lens 4, and the laser oscillation gain module 5 are all on the same side of the dichroic mirror 3. The laser oscillation gain module 5 uses a rare-earth ion-doped crystal. The rare-earth ion-doped crystal only has a rare-earth ion-doped region. The Bragg grating is inscribed at one end of the rare-earth ion-doped crystal far from the laser lens 4. The Bragg grating and the laser lens 4 form a resonant cavity, and the resonant cavity is a plane-plane cavity. The laser emitted by the pump source 1 is a semiconductor laser. The transmittance of the laser provided by the pump source 1 by the dichroic mirror 3 is 2%, and the reflectance is 98%. The reflectance of the laser wavelength emitted by the laser oscillation gain module 5 is 98%, and the transmittance is 2%. The transmittance of the laser emitted by the laser oscillation gain module 5 by the laser lens 4 is 1%-50%, preferably 10%.

[0053] Example 4:

[0054] As Figure 4 shown, the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 are arranged in a straight line. The dichroic mirror 3 and the laser oscillation gain module 5 are arranged in a straight line. The angle between the mirror surface of the dichroic mirror 3 and the optical path direction is 45°. That is, the straight-line arrangement direction of the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 and the straight-line arrangement direction of the dichroic mirror 3 and the laser oscillation gain module 5 form a 90° angle. The pump source 1, the pump light coupling device 2, and the laser oscillation gain module 5 are all on the same side of the dichroic mirror 3. A coating is deposited on the side of the laser oscillation gain module 5 close to the dichroic mirror 3. The laser oscillation gain module 5 uses a rare-earth ion-doped crystal. The rare-earth ion-doped crystal only has a rare-earth ion-doped region. The Bragg grating is inscribed at one end of the rare-earth ion-doped crystal far from the coating. The Bragg grating and the coating form a resonant cavity, and the resonant cavity is a plane-plane cavity. The laser emitted by the pump source 1 is a semiconductor laser. The transmittance of the laser provided by the pump source 1 by the dichroic mirror 3 is 2%, and the reflectance is 98%. The reflectance of the laser wavelength emitted by the laser oscillation gain module 5 is 98%, and the transmittance is 2%. The transmittance of the laser emitted by the laser oscillation gain module 5 by the coating is 1%-50%, preferably 10%.

[0055] Example 5:

[0056] As Figure 5As shown, the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 are arranged in a straight line. The dichroic mirror 3, the laser lens 4, and the laser oscillation gain module 6 are arranged in a straight line. The angle between the mirror surface of the dichroic mirror 3 and the optical path direction is 45°. That is, the straight-line arrangement direction of the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 and the straight-line arrangement direction of the dichroic mirror 3, the laser lens 4, and the laser oscillation gain module 6 form a 90° angle. The pump source 1, the pump light coupling device 2, the laser lens 4, and the laser oscillation gain module 6 are all on the same side of the dichroic mirror 3. The laser oscillation gain module 6 uses a rare-earth ion-doped crystal. The rare-earth ion-doped crystal has a doped rare-earth ion region close to the laser lens 4 and an undoped rare-earth ion region at one end of the doped rare-earth ion region away from the laser lens 4. Here, the Bragg grating is completely inscribed in the undoped rare-earth ion region. The Bragg grating and the laser lens 4 form a resonant cavity. The resonant cavity is a plane-plane cavity. Compared with Example 1, when the length of the crystal doped with rare-earth ions is the same, the effective cavity length can be increased, and the optical-optical conversion efficiency can be improved. The laser emitted by the pump source 1 is a semiconductor laser. The transmittance of the laser provided by the pump source 1 through the dichroic mirror 3 is 2%, and the reflectance is 98%. The reflectance of the laser wavelength emitted by the laser oscillation gain module 6 through the dichroic mirror 3 is 98%, and the transmittance is 2%. The transmittance of the laser emitted by the laser oscillation gain module 6 through the laser lens 4 is 1%-50%, preferably 10%.

[0057] Example Six:

[0058] As Figure 6 It should be noted that there seems to be some incorrect information in the original text you provided. For example, the transmittance and reflectance data in the description do not match the normal situation. I have translated it according to the original text as much as possible. You may need to check and correct the relevant content.As shown, the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 are arranged in a straight line, and the dichroic mirror 3 and the laser oscillation gain module 6 are arranged in a straight line. The angle between the mirror surface of the dichroic mirror 3 and the optical path direction is 45°, that is, the straight line arrangement direction of the pump source 1, the pump light coupling device 2, and the dichroic mirror 3 and the straight line arrangement direction of the dichroic mirror 3 and the laser oscillation gain module 6 form a 90° angle. The pump source 1, the pump light coupling device 2, and the laser oscillation gain module 6 are all on the same side of the dichroic mirror 3. A coating is deposited on the side of the laser oscillation gain module 6 close to the dichroic mirror 3. The laser oscillation gain module 6 uses a rare earth ion-doped crystal. The rare earth ion-doped crystal has a doped rare earth ion region close to the laser lens 4 and an undoped rare earth ion region at one end of the doped rare earth ion region away from the laser lens 4. Here, the Bragg grating is completely inscribed in the undoped rare earth ion region. The Bragg grating and the laser lens 4 form a resonant cavity, and the resonant cavity is a plane-plane cavity. Compared with the first example, when the length of the crystal doped rare earth ion region is the same, the effective cavity length can be increased, and the optical-optical conversion efficiency can be improved; the laser emitted by the pump source 1 is a semiconductor laser. The transmittance of the laser provided by the pump source 1 by the dichroic mirror 3 is 2%, and the reflectance is 98%. The reflectance of the laser wavelength emitted by the laser oscillation gain module 6 by the dichroic mirror 3 is 98%, and the transmittance is 2%; the transmittance of the laser emitted by the laser oscillation gain module 6 by the laser lens 4 is 1%-50%, preferably 10%.

[0059] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. It should be noted that there may be some inaccuracies in the original text data, such as the description of the transmittance and reflectance data in the middle part of the text of which seems to be inconsistent with common sense. You can check and correct it according to the actual situation.

Claims

1. A monolithic single-frequency solid-state laser based on a volume grating, characterized in that: It includes a pump source, a pump light coupling device, a dichroic mirror, a laser lens and a laser oscillation gain module which are sequentially arranged along the optical path direction; The pump source is used to emit laser light of a wavelength that can be absorbed by the laser lens; The pump light coupling device is used to focus the laser light emitted by the pump source through the dichroic mirror into the laser lens; The dichroic mirror is used to transmit the laser light emitted by the pump source and also to reflect the laser light emitted by the laser oscillation gain module; The laser lens is used to partially transmit the laser emitted by the laser oscillation gain module; The laser oscillation gain module comprises a rare earth ion doped crystal inscribed with a Bragg grating of uniform period, and the Bragg grating has a frequency selection function.

2. The monolithic single-frequency solid-state laser based on volume grating according to claim 1, characterized in that: The rare earth ion doped crystal includes a rare earth ion doped region and / or a rare earth ion undoped region in the light path direction; The Bragg grating is inscribed in the rare earth ion doped region; and / or, the Bragg grating is inscribed in the rare earth ion undoped region.

3. The monolithic single-frequency solid-state laser based on volume grating according to claim 2, characterized in that: The Bragg grating meets the following conditions: Λ=-mλ / 2m=1, 2, 3... Among them, Λ is the grating period and λ is the frequency selection wavelength.

4. The monolithic single-frequency solid-state laser based on volume grating according to claim 2, characterized in that: The rare earth ions include neodymium ions, ytterbium ions, thulium ions or holmium ions.

5. The monolithic single-frequency solid-state laser based on volume grating according to claim 1, characterized in that: The dichroic mirror has a transmittance greater than 50% for the laser light provided by the pump source, and a reflectivity greater than 50% for the laser wavelength emitted by the laser oscillation gain module.

6. The monolithic single-frequency solid-state laser based on volume grating according to claim 1, characterized in that: The transmittance of the laser lens to the laser emitted by the laser oscillation gain module is 1%-50%.

7. The monolithic single-frequency solid-state laser based on volume grating according to claim 1, characterized in that: The laser lens is replaced by a coating coated on a side of the laser oscillation gain module close to the dichroic mirror. The coating has partial transmittance to the laser emitted by the Bragg grating, and the coating and the Bragg grating form a resonant cavity.

8. The monolithic single-frequency solid-state laser based on volume grating according to claim 7, characterized in that: The transmittance of the coating to the laser emitted by the Bragg grating is 1%-50%.

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