Optically pumped semiconductor laser with integrated frequency conversion crystal

Abstract

The present invention relates to the field of laser technology, and in particular to an optically pumped semiconductor laser integrated with a frequency conversion crystal, comprising: a pump cavity; a heat dissipation structure, a nonlinear crystal, and an output coupling mirror disposed in a light exit window, wherein the heat dissipation structure, the nonlinear crystal, and the output coupling mirror are sequentially spaced apart in the light exit window in a direction away from the pump cavity; a gain chip disposed in the pump cavity, wherein the top surface of the gain chip is bonded to the surface of the heat dissipation structure facing the pump cavity; a reflector, wherein the reflector is disposed on the surface of the bottom sidewall facing the pump cavity, and the reflector is directly opposite to the gain chip, and is used to form a resonant cavity with the output coupling mirror; and a plurality of pump units, wherein the plurality of pump units are used to emit pump light toward the bottom and side surfaces of the gain chip. The present invention is at least beneficial to improving the integration level of the optically pumped semiconductor laser integrated with the frequency conversion crystal, and is beneficial to ensuring that the optically pumped semiconductor laser integrated with the frequency conversion crystal has better performance.

Description

Technical Field

[0001] The invention belongs to the technical field of lasers, and in particular relates to an optically pumped semiconductor laser integrated with a frequency conversion crystal. Background Art

[0002] Optically pumped vertical external-cavity surface-emitting semiconductor lasers (VECSELs) feature a unique external resonant cavity structure. Adjusting the external cavity mirror parameters and the cavity length allows for control of the intracavity output mode. The gain chip of an optically pumped VECSL can utilize semiconductor material band engineering to design the output wavelength. Combined with intracavity frequency conversion, it achieves wide wavelength coverage from the visible to the near-infrared. With advantages such as excellent beam quality and high output power, it has found widespread application in fields such as marine resource exploration, industrial processing, and laser medical treatment.

[0003] Optically pumped vertical external cavity surface emitting semiconductor lasers can achieve laser output in the visible light band through intracavity frequency conversion. However, traditional optically pumped vertical external cavity surface emitting semiconductor lasers use tilted pumping or bottom pumping structures. In the tilted pumping structure, the nonlinear crystal placed on the surface of the gain chip blocks the injection of pump light. The gain chip of the bottom pumping structure has low pump light absorption efficiency. The use of a V-cavity structure makes the overall system more complex and difficult to integrate into a compact module. Therefore, traditional optically pumped vertical external cavity surface emitting semiconductor lasers find it difficult to achieve high-efficiency, high-power, small size, and high-beam-quality visible light laser modules. Summary of the Invention

[0004] In view of this, the present invention aims to provide an optically pumped semiconductor laser with an integrated frequency conversion crystal, which is at least beneficial to improving the integration level of the optically pumped semiconductor laser with an integrated frequency conversion crystal, and is beneficial to ensuring that the optically pumped semiconductor laser with an integrated frequency conversion crystal has better performance.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The present invention provides an optically pumped semiconductor laser with an integrated frequency conversion crystal, comprising: a pump cavity, the pump cavity being surrounded by a top sidewall, a bottom sidewall and an annular sidewall, the top sidewall and the bottom sidewall being arranged opposite to each other, the annular sidewall being located between the top sidewall and the bottom sidewall, the top sidewall having a light exit window communicating with the pump cavity, and at least the surface of the bottom sidewall facing the pump cavity being curved; a heat dissipation structure, a nonlinear crystal and an output coupling mirror being arranged in the light exit window, wherein the heat dissipation structure, the nonlinear crystal and the output coupling mirror are arranged in sequence in a direction away from the pump cavity in the light exit window; A gain chip is placed in the pump cavity, the top surface of the gain chip is bonded to the surface of the heat dissipation structure facing the pump cavity, and the gain chip is an optically pumped gain medium chip without a DBR structure; a reflector is arranged on the surface of the bottom side wall facing the pump cavity, and the reflector is directly opposite to the gain chip, and the reflector is used to form a resonant cavity with the output coupling mirror; multiple pump units are arranged on the surface of the bottom side wall facing the pump cavity and the surface of the annular side wall facing the pump cavity, and the multiple pump units are arranged on the periphery of the reflector, and the multiple pump units are used to emit pump light to the bottom surface and side surfaces of the gain chip.

[0007] Furthermore, the surface of the annular side wall facing the pump cavity is curved, and the surface of the annular side wall facing the pump cavity and the surface of the bottom side wall facing the pump cavity constitute a hemispherical inner wall. Multiple pump units are arranged on the hemispherical inner wall, and the number of layers of pump units arranged in an annular manner around the outer periphery of the reflector is multiple layers. In two adjacent layers of pump units, the pump units located in different layers are staggered with each other.

[0008] Furthermore, the top sidewall, the bottom sidewall and the annular sidewall are an integrally formed structure, and the materials of the top sidewall, the bottom sidewall and the annular sidewall are the same, and the materials of the top sidewall, the bottom sidewall and the annular sidewall all include high-purity copper.

[0009] Furthermore, the surface of the heat dissipation structure facing the gain chip has a reflective film with high reflectivity for the pump light band and an anti-reflection film with high transmittance for the output light band, and the surface of the heat dissipation structure facing the nonlinear crystal has a reflective film with high reflectivity for the doubled frequency light.

[0010] Furthermore, the side surface of the heat dissipation structure is in surface contact with the inner wall surface of the light exit window.

[0011] Furthermore, the heat dissipation structure is made of a light-transmitting material, and the material of the heat dissipation structure includes diamond or sapphire.

[0012] Furthermore, the surface of the output coupling mirror facing the nonlinear crystal has a reflection film with high reflectivity for the output light band and an anti-reflection film with high transmittance for the frequency-doubled light.

[0013] Furthermore, the pump unit is a surface-emitting semiconductor laser, the gain chip is a vertical external cavity surface-emitting semiconductor laser gain chip, the gain chip includes an active region, the active region includes multiple quantum well layers and multiple barrier layers, the multiple quantum well layers are arranged at intervals, and each quantum well layer has a barrier layer on both sides, the number of quantum well layers in the active region is in the range of 5 to 50, and the thickness of a single barrier layer is in the range of 50 nm to 500 nm.

[0014] Furthermore, in a direction perpendicular to the heat dissipation structure and pointing toward the output coupling mirror, the size of the spacing region between the heat dissipation structure and the nonlinear crystal gradually increases from the heat dissipation structure toward the nonlinear crystal.

[0015] Furthermore, the inner wall of the pump cavity has a reflective film with high reflectivity for the pump light.

[0016] Compared with the existing technology, the invention can achieve the following beneficial effects: the optically pumped semiconductor laser with integrated frequency conversion crystal provided by the present invention integrates multiple high-efficiency and densely arranged pumping units and nonlinear crystals into the laser, and utilizes the densely arranged multiple pumping units to optically pump the bottom and side surfaces of the gain chip without DBR structure, thereby realizing a visible light laser module with high efficiency, high power, small size and high beam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 A schematic structural diagram of an optically pumped semiconductor laser integrated with a frequency conversion crystal according to an embodiment of the present invention;

[0019] Figure 2 A perspective top view of an optically pumped semiconductor laser with an integrated frequency conversion crystal according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] After analysis, it was found that traditional optically pumped vertical external cavity surface emitting semiconductor lasers require a separate pump source to provide pump light. The pump light is generally pumped by side tilt pumping, bottom pumping or using a dichroic mirror, which is not conducive to modular integration of the laser. When optically pumped vertical external cavity surface emitting semiconductor lasers are used for frequency conversion, a folded cavity structure is usually adopted. The nonlinear crystal is placed near the folded cavity mirror, which has poor stability and a large volume. If a straight cavity structure is used, the nonlinear crystal will be placed on the surface of the gain chip, affecting the injection of pump light.

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0023] In the description of the present invention, it should 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" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0024] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0025] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0026] refer to Figure 1 and Figure 2The present invention provides an optically pumped semiconductor laser integrated with a frequency conversion crystal, comprising: a pump cavity 101, wherein the pump cavity 101 is surrounded by a top sidewall, a bottom sidewall, and an annular sidewall, wherein the top sidewall and the bottom sidewall are arranged opposite to each other, the annular sidewall is located between the top sidewall and the bottom sidewall, the top sidewall has a light exit window communicating with the pump cavity 101, and at least the surface of the bottom sidewall facing the pump cavity 101 is curved; a heat dissipation structure 103, a nonlinear crystal 102, and an output coupling mirror 106 arranged in the light exit window, wherein the heat dissipation structure 103, the nonlinear crystal 102, and the output coupling mirror 106 are arranged in sequence in a direction away from the pump cavity 101 in the light exit window; and a gain chip arranged in the pump cavity 101. 107, the top surface of the gain chip 107 is bonded to the surface of the heat dissipation structure 103 facing the pump cavity 101, and the gain chip 107 is an optically pumped gain medium chip without a DBR structure; the reflector 105, the reflector 105 is arranged on the surface of the bottom sidewall facing the pump cavity 101, and the reflector 105 is directly opposite to the gain chip 107, and the reflector 105 is used to form a resonant cavity with the output coupling mirror 106; multiple pump units 104, the multiple pump units 104 are arranged on the surface of the bottom sidewall facing the pump cavity 101 and the surface of the annular sidewall facing the pump cavity 101, and the multiple pump units 104 are arranged on the periphery of the reflector 105, and the multiple pump units 104 are used to emit pump light to the bottom and side surfaces of the gain chip 107. In this way, pump light can be used to directly optically pump the gain medium of the gain chip 107, and both the bottom and side surfaces of the gain chip can be optically pumped, which is beneficial for increasing the pumping area and improving conversion efficiency. The DBR-free design avoids blocking the pump light by the DBR and also avoids blocking the pump light by the nonlinear crystal 102. The heat generated by the gain chip 107 is quickly conducted to the top sidewall with high heat dissipation using the heat dissipation structure 103, achieving rapid heat dissipation, which is beneficial for improving the stability of the optically pumped semiconductor laser integrated with the frequency conversion crystal. Compared with setting a DBR on the gain chip, the independent setting of the gain chip and the reflector in the present invention is beneficial for improving the flexibility of setting the resonant cavity length.

[0027] In some embodiments, the surface of the annular sidewall facing the pump cavity 101 is curved, and the surface of the annular sidewall facing the pump cavity 101 and the surface of the bottom sidewall facing the pump cavity 101 form a hemispherical inner wall 100. Multiple pump units 104 are disposed on the hemispherical inner wall. Multiple layers of pump units 104 are arranged annularly around the periphery of the reflector 105. Within two adjacent layers of pump units 104, the pump units 104 located in different layers are staggered. The multiple pump units 104 are arranged along a spherical shape, with the light emitted from the pump units 104 directed toward the gain chip 107, facilitating uniform optical pumping of the gain chip 107.

[0028] In some embodiments, the surface of the annular sidewall facing the pumping cavity 101 is annular, and the surface of the bottom sidewall facing the pumping cavity 101 is hemispherical.

[0029] In some embodiments, the top sidewall, bottom sidewall, and annular sidewall are integrally formed and made of the same material, all comprising high-purity copper. The use of high-purity copper helps ensure that the top sidewall, bottom sidewall, and annular sidewall all have excellent heat dissipation properties, thereby facilitating rapid heat dissipation and improving the stability of optically pumped semiconductor lasers integrated with frequency conversion crystals.

[0030] In some embodiments, the inner wall of the pump cavity 101 is coated with a reflective film with high reflectivity for pump light. This helps reduce pump light loss and allows pump light that is not absorbed by the gain chip 107 and strikes the inner wall of the pump cavity 101 to be reflected by the inner wall and re-enter the gain chip 107, thereby improving conversion efficiency.

[0031] In some embodiments, a metal layer composed of titanium, platinum, and gold is evaporated on the surface of the annular sidewall facing the pump cavity 101 and the surface of the bottom sidewall facing the pump cavity 101 so as to be bonded to the pump unit 104 .

[0032] It should be noted that the shape of the inner wall where the light exit window is connected to the nonlinear crystal 102 matches the shape of the outer ring of the nonlinear crystal 102, the shape of the inner wall where the light exit window is connected to the output coupling mirror 106 matches the shape of the outer ring of the output coupling mirror 106, and the shape of the inner wall where the light exit window is connected to the heat dissipation structure 103 matches the shape of the outer ring of the heat dissipation structure 103.

[0033] In some embodiments, the surface of the heat dissipation structure 103 facing the gain chip 107 is coated with a reflective film with high reflectivity in the pump light wavelength band and an anti-reflection film with high transmittance in the output light wavelength band. This helps mitigate the impact of the heat dissipation structure 103 on the transmission of the output light into the nonlinear crystal 102 and ensures that the pump light is reflected by the heat dissipation structure 103 and enters the gain chip 107 or the inner wall of the pump cavity 101, preventing pump light leakage.

[0034] In some embodiments, the surface of the heat dissipation structure 103 facing the nonlinear crystal 102 has a reflective film with high reflectivity for the frequency-doubled light, thereby preventing the frequency-doubled light from leaking into the pump cavity 101 through the heat dissipation structure 103 .

[0035] In some embodiments, the side surfaces of the heat dissipation structure 103 are in contact with the inner wall surface of the light exit window, which is beneficial to improving the thermal conductivity between the heat dissipation structure 103 and the top side wall, thereby facilitating the rapid heat dissipation of the gain chip 107 .

[0036] In some embodiments, heat dissipation structure 103 is made of a transparent material, such as diamond or sapphire. This allows heat dissipation from gain chip 107 to be quickly dissipated, while preventing heat dissipation structure 103 from obstructing the transmission of output light. In other embodiments, output coupling mirror 106 may also be made of other transparent, highly thermally conductive materials, such as quartz, glass, infrared silicon, calcium fluoride, or magnesium fluoride.

[0037] In some embodiments, the surface of the output coupling mirror 106 facing the nonlinear crystal 102 is coated with a reflective coating with high reflectivity for the output light wavelength band and an antireflection coating with high transmittance for the doubled frequency light. This not only prevents the output light from overflowing the output coupling mirror 106 but also reduces the optical loss of the doubled frequency light emitted from the output coupling mirror 106.

[0038] Specifically, the type and parameters of the output coupling mirror 106 can be adjusted based on the spot size, output power, and other performance requirements of the optically pumped semiconductor laser outputted by the integrated frequency conversion crystal. The resonant cavity length can be controlled by controlling the distance between the output coupling mirror 106 and the reflector 105. The types of the output coupling mirror 106 include, but are not limited to, a plane mirror, a plano-concave mirror, a plano-convex mirror, and an aspheric mirror.

[0039] It should be noted that the nonlinear crystal 102 in the present invention is a crystal structure that can exhibit nonlinear optical effects under the action of an external electric field or light field. The nonlinear crystal 102 realizes frequency conversion operations such as frequency doubling, difference frequency, and sum frequency through nonlinear effects. In some embodiments, the material of the nonlinear crystal 102 includes but is not limited to lithium triborate (LBO), β-barium metaborate (BBO), potassium titanyl phosphate (KTP), lithium niobate (LN) or a self-frequency doubling crystal.

[0040] Specifically, the position of the nonlinear crystal 102 may be adjusted according to the light spot distribution requirements in the resonant cavity.

[0041] It should be noted that the reflector 105 in the present invention has high reflectivity for both the pump light band and the output light band. The materials of the reflector 105 include, but are not limited to, glass, diamond, sapphire, etc. The reflector 105 and the output coupling mirror 106 form a resonant cavity, causing the output light mode to oscillate within the cavity, thereby achieving periodic gain. The type and parameters of the reflector 105 can be adjusted based on the output light spot size, output power, and other performance requirements of the optically pumped semiconductor laser with an integrated frequency conversion crystal. The types of the reflector 105 include, but are not limited to, plane mirrors, plano-concave mirrors, plano-convex mirrors, and aspheric mirrors.

[0042] In some embodiments, the pump unit 104 is a surface-emitting semiconductor laser, and the gain chip 107 is a vertical external cavity surface-emitting semiconductor laser gain chip. The gain chip 107 includes an active region, which includes multiple quantum well layers and multiple barrier layers. The multiple quantum well layers are arranged in an alternating pattern, and each quantum well layer is flanked by a barrier layer. The number of quantum well layers in the active region is in the range of 5 to 50, and the thickness of a single barrier layer is in the range of 50 nm to 500 nm. This ensures that the pump light absorption layer in the gain chip has a greater thickness, thereby improving the gain chip's absorption efficiency of the pump light.

[0043] It should be noted that the gain chip 107 does not have a distributed Bragg reflector (DBR) structure on either side, and the entire epitaxial structure of the gain chip 107 does not require doping, making it easy to manufacture. The quantum well in the active region of the gain chip 107 can be designed based on the material selection and composition of the required wavelength. The barrier layer, which serves as a pump light absorption layer, is thickened to improve pump light absorption and conversion efficiency.

[0044] The material system of the vertical external cavity surface emitting semiconductor laser gain chip can be selected according to the wavelength band requirement of the output light. For example, if the required laser wavelength is in the range of 600nm~1200nm, the vertical external cavity surface emitting semiconductor laser gain chip 107 can be selected from the gallium arsenide material system; if the required laser wavelength is in the range of 1300nm~1700nm, the vertical external cavity surface emitting semiconductor laser gain chip can be selected from the indium phosphide material system.

[0045] The material system of surface-emitting semiconductor lasers can be selected according to the required wavelength requirements of the pump light. For example, if the required pump light wavelength is in the range of 600nm~1200nm, the surface-emitting semiconductor laser can use the gallium arsenide material system; if the required pump light wavelength is in the range of 1300nm~1700nm, the surface-emitting semiconductor laser can choose the indium phosphide material system.

[0046] In some embodiments, along a direction perpendicular to the heat dissipation structure 103 and pointing toward the output coupling mirror 106, the size of the spacing region between the heat dissipation structure 103 and the nonlinear crystal 102 gradually increases from the heat dissipation structure 103 toward the nonlinear crystal 102. This facilitates good heat dissipation.

[0047] It should be noted that the top side wall, the bottom side wall and the annular side wall constitute a high thermal conductivity shell. The shape of the high thermal conductivity shell can be cylindrical, the diameter of the circular cross-section of the cylinder can be in the range of 10 mm to 500 mm, the thickness of the bottom side wall can be in the range of 3 mm to 50 mm, the thickness of the annular side wall can be in the range of 3 mm to 50 mm, the overall height of the high thermal conductivity shell can be in the range of 30 mm to 500 mm, and the curvature radius of the hemispherical inner wall can be in the range of 5 mm to 400 mm; the height of the spacing area between the nonlinear crystal 102 and the output coupling mirror 106 can be in the range of 5 mm to 100 mm; the height of the spacing area between the nonlinear crystal 102 and the heat dissipation structure 103 can be in the range of 5 mm to 100 mm.

[0048] In a specific embodiment, the heat dissipation structure 103 is a diamond with a square cross-section. The thickness of the heat dissipation structure 103 can be in the range of 1 mm to 10 mm, and the side length of the square cross-section can be in the range of 1 mm to 40 mm. The reflectivity of the reflective film thereon for the pump light band is greater than 95%, the reflectivity of the frequency-doubled light reflective film is greater than 95%, and the transmittance of the anti-reflection film thereon for the output light band is greater than 95%.

[0049] In a specific embodiment, the output coupling mirror 106 is a plano-concave mirror made of K9 glass, and the output coupling mirror 106 has a doubled frequency light output area 110. The thickness of the output coupling mirror 106 can be in the range of 1 mm to 10 mm, the diameter of the output coupling mirror 106 is in the range of 1 mm to 40 mm, the curvature radius of the output coupling mirror 106 is in the range of 10 mm to 5000 mm, the reflectivity of the reflective film on the surface of the output coupling mirror 106 to the output light is in the range of 85% to 99.9%, and the transmittance of the anti-reflection film of the output coupling mirror 106 to the doubled frequency light is greater than 95%.

[0050] In a specific embodiment, the reflector 105 is a plane mirror made of K9 glass. The thickness of the reflector 105 can be in the range of 1 mm to 10 mm, the diameter of the reflector 105 is in the range of 1 mm to 40 mm, and the reflectivity of the reflective film thereon to the pump light band is greater than 99.9%.

[0051] In some embodiments, the epitaxial structure of the gain chip 107 is a gallium arsenide material system. The epitaxial structure of the gain chip 107 includes: a substrate, the substrate can be made of GaAs material and is undoped; an active region, the active region can include multiple quantum well layers and barrier layers located on both sides of each quantum well layer. The material of the barrier layer can be AlGaAs, where the component of Al can be within the range of 0 to 0.2. The material of the quantum well layer can be InGaAs, where the In component can be within the range of 0 to 0.5. The thickness of the barrier layer can be within the range of 20 nm to 200 nm, and the thickness of the quantum well layer can be within the range of 1 nm to 20 nm. The corresponding emission wavelength band of the gain chip 107 can be within the range of 800 nm to 1300 nm; a window layer, the material of the window layer can be Al z GaAs material, where 0 < z < 1, and the thickness of the window layer can be within the range of 10 nm to 800 nm.

[0052] In some embodiments, the pump unit 104 is a surface-emitting semiconductor laser based on a gallium arsenide material system. The surface-emitting semiconductor laser includes: a substrate, the material of the substrate is N-type GaAs; an N-type DBR layer, the N-type DBR layer includes alternately arranged Al 0.25 Ga 0.75 As layers and Al 0.95 Ga 0.05 As layers. The thickness of a single layer material in the N-type DBR layer can be 1 / 4 of the output wavelength. The dopant of the N-type DBR layer can be Si, and the doping concentration of Si can be within the range of 1E16 / cm 3 ~8E18 / cm 3 ; the active region is a barrier layer / quantum well layer / barrier layer structure. The material of the barrier layer can be Al 0.42 Ga 0.58 As, and the material of the quantum well layer can be Al 0.08 Ga 0.92 As. The thickness of the barrier layer can be within the range of 20 nm to 200 nm, and the thickness of the quantum well layer can be within the range of  1 nm to 20 nm. The emission wavelength band of the surface-emitting semiconductor laser can be 600 nm to 800 nm; a P-type DBR layer, the P-type DBR layer includes Al 0.25 Ga 0.75 As and Al 0.95 Ga 0.05 As. The dopant of the P-type DBR layer can be C, and the doping concentration of C can be within the range of 1E18 / cm 3 ~1E20 / cm 3 ; an oxidation confinement layer, the material of the oxidation confinement layer is Al 0.98 Ga 0.02As, the thickness of the oxidation restriction layer can be in the range of 20 nm to 1000 nm.

[0053] It should be noted that, under the premise of meeting the heat dissipation requirements and thermal stability, the higher the arrangement density of the pump units on the inner wall of the pump cavity, the better, and the arrangement of the pump units is not restricted.

[0054] In some examples, the basic parameters of the pump unit are as follows: the wavelength is in the range of 750nm~1500nm, preferably 808nm or 940nm, which can ensure coverage of the pumping requirements of mainstream semiconductor lasers and solid-state lasers; the single-point output power is in the range of 0.01W~100W, which can be continuous or pulsed mode, and preferably the single-point output power is in the range of 0.1W~1W, so that the thermal effect and light intensity requirements can be balanced; the diameter of the pump unit can be in the range of 2mm~8mm.

[0055] In some examples, the spacing between the pump units is greater than 1.2 times the diameter of the pump units, which helps reduce thermal crosstalk.

[0056] The optically pumped semiconductor laser with integrated frequency conversion crystal provided in the above embodiment achieves intracavity frequency conversion by integrating a nonlinear crystal 102 within the resonant cavity. The use of a DBR-free gain chip 107 for bottom and side pumping avoids interference with pump light injection by the nonlinear crystal 102, increases the thickness of the pump light absorption layer of the gain chip 107, and overall improves the absorption efficiency of the gain chip 107 for pump light, thereby realizing a compact frequency conversion optically pumped vertical external cavity semiconductor laser module. Furthermore, multiple pump units 104 are densely arranged on the inner wall of the pump cavity, which helps increase pump power. The inner wall of the pump cavity is vapor-deposited with a pump light reflection layer, causing the pump light to oscillate repeatedly on the inner wall of the pump cavity, allowing unabsorbed pump light to pass through the gain chip 107 multiple times, which helps improve the absorption efficiency of the pump light.

[0057] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0058] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. An optically pumped semiconductor laser integrated with a frequency conversion crystal, characterized in that: include: A pump cavity, wherein the inner wall of the pump cavity has a reflective film with high reflectivity for pump light, the pump cavity is surrounded by a top sidewall, a bottom sidewall, and an annular sidewall, the top sidewall and the bottom sidewall are arranged opposite each other, the annular sidewall is located between the top sidewall and the bottom sidewall, the top sidewall has a light exit window communicating with the pump cavity, and at least the surface of the bottom sidewall facing the pump cavity is curved; a heat dissipation structure, a nonlinear crystal, and an output coupling mirror disposed within the light exit window, wherein the heat dissipation structure, the nonlinear crystal, and the output coupling mirror are sequentially spaced apart in a direction away from the pump cavity within the light exit window, and a side surface of the heat dissipation structure is in surface contact with an inner wall surface of the light exit window; A gain chip is provided in the pump cavity, wherein the top surface of the gain chip is bonded to the surface of the heat dissipation structure facing the pump cavity, and the gain chip is an optically pumped gain medium chip without a DBR structure; a reflector, the reflector being arranged on a surface of the bottom sidewall facing the pump cavity, the reflector being directly opposite to and spaced from the gain chip, and being used to form a resonant cavity with the output coupling mirror; a plurality of pump units, the plurality of pump units being arranged on a surface of the bottom sidewall facing the pump cavity and a surface of the annular sidewall facing the pump cavity, and the plurality of pump units being arranged around the periphery of the reflector, and the plurality of pump units being used to emit pump light toward the bottom surface and side surfaces of the gain chip; The surface of the heat dissipation structure facing the gain chip has a reflective film with high reflectivity for the pump light band, and the surface of the heat dissipation structure facing the nonlinear crystal has a reflective film with high reflectivity for the frequency-doubled light.

2. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1, characterized in that: The surface of the annular side wall facing the pump cavity is curved, and the surface of the annular side wall facing the pump cavity and the surface of the bottom side wall facing the pump cavity constitute a hemispherical inner wall. A plurality of pump units are arranged on the hemispherical inner wall. The number of layers of pump units arranged in an annular manner on the periphery of the reflector is multiple layers, and in two adjacent layers of pump units, the pump units located in different layers are staggered with each other.

3. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1 or 2, characterized in that: The top sidewall, the bottom sidewall and the annular sidewall are an integrally formed structure, and the materials of the top sidewall, the bottom sidewall and the annular sidewall are the same, and the materials of the top sidewall, the bottom sidewall and the annular sidewall are all high-purity copper.

4. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1, characterized in that: The surface of the heat dissipation structure facing the gain chip is provided with an anti-reflection film with high transmittance in the output light band.

5. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1 or 4, characterized in that: The heat dissipation structure is made of a light-transmitting material, and the material of the heat dissipation structure includes diamond or sapphire.

6. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1, characterized in that: The surface of the output coupling mirror facing the nonlinear crystal is provided with a reflection film with high reflectivity for the output light wavelength band and an anti-reflection film with high transmittance for the frequency-doubled light.

7. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1, characterized in that: The pump unit is a surface-emitting semiconductor laser, the gain chip is a vertical external cavity surface-emitting semiconductor laser gain chip, and the gain chip includes an active region, the active region includes multiple quantum well layers and multiple barrier layers, the multiple quantum well layers are arranged at intervals, and each quantum well layer has a barrier layer on both sides, the number of quantum well layers in the active region is in the range of 5 to 50, and the thickness of a single barrier layer is in the range of 50 nm to 500 nm.

8. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1, characterized in that: In a direction perpendicular to the heat dissipation structure and pointing toward the output coupling mirror, a size of a spacing region between the heat dissipation structure and the nonlinear crystal gradually increases from the heat dissipation structure toward the nonlinear crystal.

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