Solid-state laser ASE suppression method, solid-state laser preparation method and solid-state laser

Abstract

The invention provides a solid-state laser ASE suppression method, a solid-state laser preparation method and a solid-state laser. The method for suppressing ASE of the solid-state laser comprises the following steps: performing laser-level polishing on the side surface of a round-rod-shaped laser gain medium of the solid-state laser; a rare earth doped glass film layer is attached to the polished surface of the round-rod-shaped laser gain medium in an evaporation or hot melting mode; the difference between the thermal expansion coefficient of the film layer and the thermal expansion coefficient of the round-rod-shaped laser gain medium is within the range of 10 <-6 > / K, and the melting point of the film layer is lower than that of the round-rod-shaped laser gain medium; and the outer side of the rare earth doped glass film layer is plated with a dielectric film layer with high anti-reflection on the wavelength of the pump light. On the basis of not sacrificing the LD pumping efficiency, the spontaneous radiation amplification effect perpendicular to the axial direction of the laser can be effectively inhibited, the light-to-light conversion efficiency of the laser is further improved, the power consumption of the laser is reduced, and the laser beam quality is optimized.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and in particular to a method for suppressing ASE of a solid laser, a preparation method of a solid laser, and a solid laser. Background Art

[0002] With the development of optoelectronic technology, semiconductor-pumped solid lasers have flourished in many fields. Currently, the laser based on an LD-pumped rod-shaped crystal is the most reliable and widely used solid laser light source.

[0003] With the continuous improvement of the output power level of semiconductor-pumped solid lasers, the amplified spontaneous emission (ASE) effect has become an important factor restricting the improvement of laser output level and beam quality. ASE refers to the phenomenon that photons spontaneously generated inside the active medium are amplified after multiple reflections and finally escape from the laser cavity without an external signal input. It directly consumes the population of the upper laser level, thereby reducing the output efficiency and beam quality of the laser. Especially in high-energy laser amplifiers and high-peak-power compact lasers, the ASE effect will consume a large number of upper-level particles.

[0004] The ASE suppression means in related technologies include optimizing the structural design of the laser cavity, improving the coupling efficiency of the pump light, and using special optical elements, etc. However, these methods often reduce the absorption efficiency of the pump light, resulting in a reduction in the overall efficiency of the laser. Summary of the Invention

[0005] The present invention provides a method for suppressing ASE of a solid laser, a preparation method of a solid laser, and a solid laser, and solves the problem of how to suppress ASE of a solid laser.

[0006] To achieve the above object, the present application adopts the following technical solutions: In a first aspect, a method for suppressing ASE of a solid laser is provided, including: Laser-grade polishing is performed on the side surface of the rod-shaped laser gain medium of the solid laser; A rare-earth doped glass film layer is attached to the polished surface of the rod-shaped laser gain medium by evaporation or hot melting; the film layer thickness is in the micron level, and the difference in thermal expansion coefficient from the rod-shaped laser gain medium is within 10 -6 / K, and the melting point is lower than the melting point of the rod-shaped laser gain medium; A dielectric film layer with high anti-reflection for the pump light wavelength is deposited on the outside of the rare-earth doped glass film layer.

[0007] In a first possible implementation manner of the first aspect, it further includes: Laser-level polish the two end faces of the rod-shaped laser gain medium, and deposit an antireflection dielectric film layer with a set wavelength.

[0008] In a second aspect, a method for preparing a solid-state laser is provided, including: Select a rod-shaped Nd:YAG crystal and perform laser-level polishing on its side surface; Attach a glass film layer doped with Sm 3+ ions to the polished surface of the rod-shaped Nd:YAG crystal by evaporation coating or hot melting. The film layer has a thickness of 3 to 5 micrometers, and the difference in thermal expansion coefficient from the rod-shaped Nd:YAG crystal is within 10 -6 / K, and the melting point is lower than that of the YAG material; Deposit an antireflection dielectric film layer with a wavelength of 808 nm for the pump light on the outer side of the glass film layer doped with Sm 3+ ions; Laser-level polish the two end faces of the rod-shaped Nd:YAG crystal, and deposit an antireflection dielectric film layer with a wavelength of 1064 nm to obtain a composite rod-shaped laser crystal; Combine the composite rod-shaped laser crystal with a plurality of heat sinks by indium soldering.

[0009] In a first possible implementation manner of the second aspect, the material of the heat sink is oxygen-free copper. The specific number of the heat sinks depends on the dimension of the LD pump array. The dimension of the LD pump array is 3 / 5 / 7 dimensions. The center wavelength of a single LD pump array is 808 nm, and the peak power is 1000 to 3000 W. A plurality of the heat sinks and a plurality of the LD pump arrays are alternately and equidistantly arranged around the outside of the composite rod-shaped laser crystal.

[0010] In a first possible implementation manner of the second aspect, the doping concentration of the rod-shaped Nd:YAG crystal is 0.5 to 0.8 at.%.

[0011] In a third aspect, a solid-state laser is provided, including: A composite rod-shaped laser crystal, an LD pump array, and a heat sink; The composite rod-shaped laser crystal includes: a rod-shaped Nd:YAG crystal, whose side surface is a laser-level polished surface; the polished surface is combined with a glass film layer doped with Sm 3+ ions by evaporation coating and hot melting. The film layer has a thickness of 3 to 5 micrometers, and the difference in thermal expansion coefficient from the rod-shaped Nd:YAG crystal is within 10 -6 / K, and the melting point is lower than that of the YAG material; the outer side of the glass film layer doped with Sm 3+ ions is coated with an antireflection dielectric film layer with a wavelength of 808 nm for the pump light; The dimension of the LD pumping array is 3 / 5 / 7 dimensions, the central wavelength of a single LD pumping array is 808 nm, and the peak power is 1000 - 3000 W; A plurality of the heat sinks and a plurality of the LD pumping arrays are alternately and equidistantly arranged around the outside of the composite rod-shaped laser crystal.

[0012] In the first possible implementation manner of the third aspect, the doping concentration of the cylindrical Nd:YAG crystal is 0.5 - 0.8 at.%.

[0013] In the second possible implementation manner of the third aspect, both end faces of the cylindrical Nd:YAG crystal are laser-grade polished surfaces and are coated with an antireflection dielectric film layer with a wavelength of 1064 nm.

[0014] The method for suppressing ASE of a solid-state laser of the present invention has the following advantages: On the basis of not sacrificing the LD pumping efficiency, it effectively suppresses the amplified spontaneous emission (ASE) effect perpendicular to the laser axis, further improves the optical-optical conversion efficiency of the laser (converting the pump light energy of the laser into laser output energy), reduces the power consumption of the laser, and optimizes the laser beam quality.

[0015] The preparation method of the solid-state laser corresponding to the method for suppressing ASE of a solid-state laser of the present invention and the solid-state laser can achieve the same technical effects. To avoid repetition, they will not be elaborated here. Description of the Drawings

[0016] Figure 1 It is a schematic flow chart of a method for suppressing ASE of a solid-state laser provided by an embodiment of the present application; Figure 2 It is a schematic flow chart of a preparation method of a solid-state laser provided by an embodiment of the present application; Figure 3 It is a schematic structural diagram of a composite rod-shaped laser crystal provided by an embodiment of the present application; Figure 4 It is a schematic structural diagram of a solid-state laser provided by an embodiment of the present application.

[0017] Reference Signs: Cylindrical Nd:YAG crystal 1; Glass film layer 2 doped with Sm 3+ Ion; Antireflection dielectric film layer 3; LD pumping array 4; Heat sink 5. Detailed Embodiments

[0018] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined purpose, the technical solutions in the embodiments of the present application are clearly described. Obviously, the described embodiments are part of the embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0019] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are usually of the same type, and the number of objects is not limited. For example, the first object can be one or multiple. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally represents an "or" relationship between the associated objects before and after.

[0020] In the description of the method flow in the specification of the present application and the steps in the flow chart in the accompanying drawings of the present invention, it is not necessary to strictly execute according to the step numbers. The execution order of the method steps can be changed. Moreover, certain steps can be omitted, multiple steps can be combined into one step for execution, and / or one step can be decomposed into multiple steps for execution.

[0021] The following will be described in detail with reference to the accompanying drawings and preferred embodiments for the method for suppressing ASE of a solid-state laser, the preparation method of a solid-state laser, and the solid-state laser provided by the embodiments of the present application as follows.

[0022] In a typical 1064nm laser rangefinder illuminator, there are high-standard requirements for the laser source in terms of light weight, compactness, high peak power, and high beam quality. The heat and high beam quality of a solid-state laser are two contradictory target parameters, and it is often impossible to have both. This is mainly because there is a large gap between the laser conversion efficiency and the theoretical quantum conversion efficiency due to the ASE effect. Therefore, how to effectively suppress the ASE effect has always been a hot topic in the development of solid-state lasers.

[0023] Please refer to Figure 1 , the embodiments of the present application provide a method for suppressing ASE of a solid-state laser. As Figure 1 shown, the method of the embodiments of the present application includes: Step A1, perform laser-grade polishing on the side surface of the rod-shaped laser gain medium of the solid-state laser.

[0024] Step A2, attach a rare-earth doped glass film layer to the polished surface of the rod-shaped laser gain medium by evaporation or hot melting; the thickness of the film layer is in the micron range, and the difference in the coefficient of thermal expansion from the rod-shaped laser gain medium is within 10-6 within the range of / K, the melting point is lower than that of the rod-shaped laser gain medium.

[0025] Step A3, deposit a dielectric film layer with high antireflection for the pump light wavelength on the outer side of the rare earth doped glass film layer.

[0026] In some possible embodiments, it further includes: Step A4, perform laser-grade polishing on both end faces of the rod-shaped laser gain medium, and deposit an antireflection dielectric film layer with a set wavelength.

[0027] The principle of the above method for suppressing amplified spontaneous emission of the solid laser is as follows: The rare earth ions in the glass film layer have very weak absorption of the pump light, and are even transparent to the pump light. Therefore, the pump light can penetrate the glass film layer unhindered and be absorbed by the laser crystal, so that the LD pump efficiency will not be sacrificed; the rare earth doped glass film layer can absorb the light of the output laser wavelength. By attaching a rare earth doped glass film layer capable of absorbing the output laser wavelength to the side of the laser crystal, the amplified spontaneous emission amplification effect perpendicular to the laser axis can be effectively suppressed. When the photons of spontaneous emission attempt to propagate along the side of the laser crystal, they will be absorbed by the glass film layer, thereby reducing the occurrence of ASE. Since ASE is effectively suppressed, more pump light energy can be converted into useful laser output instead of being wasted in the ASE process. Therefore, the ratio of the pump light energy of the laser converted into laser output energy is increased, thereby improving the overall performance of the laser.

[0028] Please refer to Figure 2 , the embodiment of the present application provides a method for preparing a solid laser, as Figure 2 shown, the preparation method of the embodiment of the present application includes: Step S1, select a rod-shaped Nd:YAG crystal and perform laser-grade polishing on its side; wherein, the doping concentration of the rod-shaped Nd:YAG crystal is 0.5~0.8 at.%.

[0029] Specifically in implementation, the diameter of the rod-shaped Nd:YAG crystal is generally 4~7 mm, and the length is 30~50 mm.

[0030] Step S2, attach a glass film layer doped with Sm 3+ ions on the polished surface of the rod-shaped Nd:YAG crystal by evaporation or hot melting, the film layer thickness is 3~5 microns, and the difference in thermal expansion coefficient from the rod-shaped Nd:YAG crystal is within 10 -6 / K, and the melting point is lower than that of the YAG material.

[0031] The glass film layer doped with Sm 3+ ions has a thickness at the micron level, and Sm in the film layer material 3+It can absorb 1064 nm laser light and does not absorb the pump light in the 808 nm band. Its melting point is lower than that of the YAG material, that is, lower than the melting point of the rod-shaped Nd:YAG crystal.

[0032] Step S3, deposit an antireflection dielectric film layer with a wavelength of 808 nm pump light on the outer side of the glass film layer doped with Sm 3+ ions.

[0033] After attaching the glass film layer doped with Sm 3+ ions to the polished surface by evaporation coating or hot melting, deposit an 808 nm antireflection film on the outermost side to eliminate the Fresnel loss on the pump incident surface and improve the pump efficiency.

[0034] Step S4, perform laser-level polishing on both end faces of the rod-shaped Nd:YAG crystal and deposit an antireflection dielectric film layer with a wavelength of 1064 nm to obtain a composite rod-shaped laser crystal, so as to promote the effective transmission of laser light and reduce the end face reflection loss.

[0035] Step S5, combine the composite rod-shaped laser crystal with multiple heat sinks by indium soldering.

[0036] The heat sink is used for crystal heat conduction. In some possible embodiments, the material of the heat sink is copper. Refer to Figure 4 for details. The specific number of heat sinks depends on the dimension of the LD pump array. The dimension of the LD pump array is 3 / 5 / 7 dimensions. The central wavelength of a single LD pump array is 808 nm, and the peak power is 1000 - 3000 W. Multiple heat sinks and multiple LD pump arrays are alternately and equidistantly surrounded outside the composite rod-shaped laser crystal.

[0037] Refer to Figure 3-4 . Corresponding to the embodiment of the preparation method of the above solid laser, the embodiment of the present application provides a solid laser, which includes: A composite rod-shaped laser crystal, an LD pump array 4 and a heat sink 5; The composite rod-shaped laser crystal includes: a rod-shaped Nd:YAG crystal 1 with a doping concentration of 0.5 - 0.8 at.%, and its side surface is a laser-level polished surface; the polished surface is combined with a glass film layer 2 doped with Sm 3+ ions by evaporation coating and hot melting. The film layer thickness of the glass film layer is 3 - 5 microns, and the difference in the coefficient of thermal expansion from the rod-shaped Nd:YAG crystal is within 10 -6 / K, and the melting point is lower than that of the YAG material; the outer side of the glass film layer doped with Sm 3+ ions is coated with an antireflection dielectric film layer 3 with a wavelength of 808 nm pump light; The dimension of the LD pump array 4 is 3 / 5 / 7 dimensions. The central wavelength of a single LD pump array 4 is 808 nm, and the peak power is 1000 - 3000 W; A plurality of heat sinks 5 and a plurality of LD pumping arrays 4 are alternately and equidistantly arranged around the outside of the composite rod-shaped laser crystal.

[0038] In some possible embodiments, the two end faces of the round rod-shaped Nd:YAG crystal are laser-grade polished surfaces and are coated with an antireflection dielectric film layer with a wavelength of 1064 nm.

[0039] This application has the following effects and advantages: On the basis of not sacrificing the LD pumping efficiency, it effectively suppresses the amplified spontaneous emission (ASE) effect perpendicular to the laser axis, further improves the optical-optical conversion efficiency of the laser (the pump light energy of the laser is converted into the laser output energy), reduces the power consumption of the laser, and optimizes the laser beam quality.

[0040] It should be noted that in this article, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including that element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of this application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0041] It can be understood that the embodiments of this application have been described above in conjunction with the accompanying drawings, but this application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Those skilled in the art know that without departing from the spirit and scope of the present invention, these features and embodiments can be variously changed or equivalently replaced. In addition, those of ordinary skill in the art, under the inspiration or teaching of this application, can modify these features and embodiments to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A method for suppressing solid-state laser ASE, characterized in that: include: For the round rod-shaped laser gain medium of the solid laser, the side surface is laser-grade polished; A rare earth doped glass film layer is attached to the polished surface of the round rod-shaped laser gain medium by evaporation or hot melting; the thickness of the film layer is micron-level, and the difference in thermal expansion coefficient between the film layer and the round rod-shaped laser gain medium is within 10 -6 / K range, the melting point is lower than the melting point of the round rod-shaped laser gain medium; A dielectric film layer with high transmittance enhancement for the wavelength of pump light is plated on the outer side of the rare earth doped glass film layer.

2. The method for suppressing solid-state laser ASE according to claim 1, characterized in that: Also includes: Laser-grade polishing is performed on both end faces of the round rod-shaped laser gain medium, and an anti-reflection medium film layer of a set wavelength is plated.

3. A method for preparing a solid laser, characterized in that: include: A round rod-shaped Nd:YAG crystal was selected and its side was laser-polished; The polished surface of the round rod-shaped Nd:YAG crystal is doped with Sm by evaporation or hot melting. 3+ The glass film layer of the ion has a thickness of 3 to 5 microns and a thermal expansion coefficient difference of 10 -6 / K range, the melting point is lower than that of YAG material; In the doped Sm 3+ The outer side of the ion glass film layer is coated with an anti-reflection dielectric film layer with a pump light wavelength of 808nm; Laser-grade polishing is performed on both end faces of the round rod-shaped Nd:YAG crystal, and a 1064nm wavelength anti-reflection medium film is plated to obtain a composite rod-shaped laser crystal; The composite rod-shaped laser crystal is combined with a plurality of heat sinks by indium welding.

4. The method for preparing a solid-state laser according to claim 3, characterized in that: The material of the heat sink is copper, and the specific number of the heat sinks depends on the dimension of the LD pump array. The dimension of the LD pump array is 3 / 5 / 7 dimensions. The central wavelength of a single LD pump array is 808nm, and the peak power is 1000~3000W; multiple heat sinks and multiple LD pump arrays are alternately and equidistantly surrounded by the outside of the composite rod-shaped laser crystal.

5. The method for preparing a solid-state laser according to claim 3, characterized in that: The doping concentration of the round rod-shaped Nd:YAG crystal is 0.5-0.8 at.%.

6. A solid-state laser, characterized in that: include: Composite rod laser crystal, LD pump array and heat sink; The composite rod-shaped laser crystal comprises: a round rod-shaped Nd:YAG crystal, the side of which is a laser-grade polished surface; the polished surface is combined with doped Sm by evaporation and hot melting. 3+ The glass film layer of the ion has a thickness of 3 to 5 microns and a thermal expansion coefficient difference of 10 -6 / K range, the melting point is lower than that of YAG material; the doped Sm 3+ The outer side of the ion glass film layer is coated with an anti-reflection dielectric film layer with a pump light wavelength of 808nm; The dimension of the LD pump array is 3 / 5 / 7 dimensions, the central wavelength of a single LD pump array is 808nm, and the peak power is 1000~3000W; The plurality of heat sinks and the plurality of LD pump arrays are alternately and equidistantly surrounded on the outside of the composite rod-shaped laser crystal.

7. The solid-state laser according to claim 6, characterized in that: The doping concentration of the round rod-shaped Nd:YAG crystal is 0.5-0.8 at.%.

8. The recommendation method based on hypergraph and multi-behavior contrastive learning according to claim 1, characterized in that: Both end faces of the round rod-shaped Nd:YAG crystal are laser-grade polished surfaces and are coated with a 1064nm wavelength anti-reflection medium film layer.

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