Optical pumping semiconductor laser integrated with frequency conversion crystal

Abstract

The invention relates to the technical field of lasers, in particular to an optical pumping semiconductor laser integrated with a frequency conversion crystal. The heat dissipation structure, the nonlinear crystal and the output coupling mirror are arranged in the light emitting window, and the heat dissipation structure, the nonlinear crystal and the output coupling mirror are sequentially arranged at intervals in the light emitting window in the direction away from the pumping cavity; the gain chip is arranged in the pumping cavity, and the top surface of the gain chip is bonded with the surface, facing the pumping cavity, of the heat dissipation structure; the reflecting mirror is arranged on the surface, facing the pumping cavity, of the side wall of the bottom, the reflecting mirror is right opposite to the gain chip, and the reflecting mirror is used for forming a resonant cavity with the output coupling mirror; and the plurality of pumping units are used for emitting pumping light to the bottom surface and the side surface of the gain chip. According to the invention, the integration level of the optical pumping semiconductor laser integrated with the frequency conversion crystal is at least improved, and the optical pumping semiconductor laser integrated with the frequency conversion crystal is ensured to have excellent performance.

Description

Technical Field

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

[0002] The optically pumped vertical external cavity surface emitting semiconductor laser has a unique external resonator structure. By adjusting the parameters of the external cavity mirror and the cavity length of the resonator, the control of the output mode inside the cavity can be achieved. The gain chip of the optically pumped vertical external cavity surface emitting semiconductor laser can design the output wavelength using the energy band engineering of semiconductor materials. Combining frequency conversion inside the cavity can achieve a wide wavelength coverage range from visible light to near-infrared. It has advantages such as good beam quality and high output power, and has been widely used in fields such as marine resource exploration, industrial processing, and laser medicine.

[0003] The optically pumped vertical external cavity surface emitting semiconductor laser can achieve laser output in the visible light band through frequency conversion inside the cavity. However, the traditional optically pumped vertical external cavity surface emitting semiconductor laser adopts an inclined pumping or bottom pumping structure. In the inclined pumping structure, the nonlinear crystal placed on the surface of the gain chip will block the injection of pump light. The pump light absorption efficiency of the gain chip in the bottom pumping structure is relatively low, and the use of a V-cavity structure will make the overall system more complex and difficult to be integrated into a compact module. Therefore, it is difficult for the traditional optically pumped vertical external cavity surface emitting semiconductor laser to achieve a visible light laser module with high efficiency, high power, small volume, and high beam quality. Summary of the Invention

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

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: The present invention provides an optically pumped semiconductor laser integrated with a frequency conversion crystal, comprising: a pump cavity surrounded by a top sidewall, a bottom sidewall, and an annular sidewall, the top sidewall and the bottom sidewall being oppositely arranged, the annular sidewall being located between the top sidewall and the bottom sidewall, the top sidewall having a light output 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 disposed in the light output window, wherein the heat dissipation structure, the nonlinear crystal, and the output coupling mirror are sequentially spaced apart in the light output window in a direction away from the pump cavity; a gain chip disposed in the pump cavity, the top surface of the gain chip being bonded to the surface of the heat dissipation structure facing the pump cavity, the gain chip being a gain medium chip with an optically pumped DBR-free structure; a reflecting mirror disposed on the surface of the bottom sidewall facing the pump cavity and facing the gain chip directly, the reflecting mirror being used to form a resonant cavity with the output coupling mirror; and a plurality of pump units disposed on the surface of the bottom sidewall facing the pump cavity and the surface of the annular sidewall facing the pump cavity, and the plurality of pump units being arranged around the periphery of the reflecting mirror, the plurality of pump units being used to emit pump light to the bottom surface and the side surface of the gain chip.

[0006] Further, the surface of the annular sidewall facing the pump cavity is curved, and the surface of the annular sidewall facing the pump cavity and the surface of the bottom sidewall facing the pump cavity form a hemispherical inner wall, the plurality of pump units being disposed on the hemispherical inner wall, the number of layers of the pump units arranged in a circular pattern around the periphery of the reflecting mirror being multiple, and in adjacent two layers of pump units, the pump units located in different layers are staggered from each other.

[0007] Further, the top sidewall, the bottom sidewall, and the annular sidewall are of 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.

[0008] Further, the surface of the heat dissipation structure facing the gain chip has a reflective film with a high reflectivity for the pump light band and an antireflection film with a high transmittance for the output light band, and the surface of the heat dissipation structure facing the nonlinear crystal has a reflective film with a high reflectivity for the second harmonic generation light.

[0009] Further, the side surface of the heat dissipation structure is in surface contact with the inner wall surface of the light output window.

[0010] Further, the heat dissipation structure is made of a light-transmitting material, and the material of the heat dissipation structure includes diamond or sapphire.

[0011] Further, the surface of the output coupling mirror facing the nonlinear crystal has a reflective film with a high reflectivity for the output light band and an antireflection film with a high transmittance for the second harmonic generation light.

[0012] Further, the pumping 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 a plurality of quantum well layers and a plurality of barrier layers, the plurality of quantum well layers are arranged at intervals, and there is a barrier layer on both sides of each quantum well 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.

[0013] Further, in the direction perpendicular to the heat dissipation structure and pointing to the output coupling mirror, the size of the interval region between the heat dissipation structure and the nonlinear crystal gradually increases from the heat dissipation structure to the nonlinear crystal.

[0014] Further, the inner wall of the pumping cavity has a reflective film with a high reflectivity to the pumping light.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: The optically pumped semiconductor laser integrating a frequency conversion crystal provided by the present invention integrates a plurality of pumping units with high efficiency and dense arrangement and a nonlinear crystal into the laser, and uses the plurality of densely arranged pumping units to optically pump the bottom surface and the side surface of the gain chip without a DBR structure, so that a visible light laser module with high efficiency, high power, small volume and high beam quality can be realized. Description of the Drawings

[0016] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 is a schematic structural diagram of the optically pumped semiconductor laser integrating a frequency conversion crystal according to an embodiment of the present invention; Figure 2 is a perspective top view of the optically pumped semiconductor laser integrating a frequency conversion crystal according to an embodiment of the present invention. Detailed Embodiments

[0017] Through analysis, it is found that the traditional optically pumped vertical external cavity surface-emitting semiconductor laser requires a separate pumping source to provide pumping light. The pumping light generally adopts the methods of lateral inclined pumping, bottom pumping or pumping using a dichroic mirror, which is not conducive to the modular integration of the laser. When the optically pumped vertical external cavity surface-emitting semiconductor laser performs frequency conversion, a folded cavity structure is usually adopted, and the nonlinear crystal is placed near the folded cavity mirror, with poor stability and large volume. If a straight cavity structure is adopted, the nonlinear crystal will be placed on the surface of the gain chip, affecting the injection of the pumping light.

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be 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 to the present invention.

[0019] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 to the present invention. In addition, terms such as "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0022] The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0023] Reference Figure 1 and Figure 2, the present invention provides an optically pumped semiconductor laser integrated with a frequency conversion crystal, comprising: a pump cavity 101 surrounded by a top sidewall, a bottom sidewall and an annular sidewall, the top sidewall and the bottom sidewall being oppositely arranged, the annular sidewall being located between the top sidewall and the bottom sidewall, the top sidewall having a light output window communicating with the pump cavity 101, and at least the surface of the bottom sidewall facing the pump cavity 101 being curved; a heat dissipation structure 103, a nonlinear crystal 102 and an output coupling mirror 106 disposed in the light output window, wherein the heat dissipation structure 103, the nonlinear crystal 102 and the output coupling mirror 106 are sequentially arranged at intervals in the light output window in a direction away from the pump cavity 101; a gain chip 107 disposed in the pump cavity 101, the top surface of the gain chip 107 being bonded to the surface of the heat dissipation structure 103 facing the pump cavity 101, and the gain chip 107 being a gain medium chip with an optically pumped DBR-free structure; a reflector 105 disposed on the surface of the bottom sidewall facing the pump cavity 101 and being opposite to the gain chip 107, the reflector 105 being used to form a resonant cavity with the output coupling mirror 106; a plurality of pump units 104 disposed 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 plurality of pump units 104 being arranged on the outer periphery of the reflector 105, the plurality of pump units 104 being used to emit pump light to the bottom surface and the side surface of the gain chip 107. In this way, the gain medium of the gain chip 107 can be directly optically pumped by the pump light, and both the bottom surface and the side surface of the gain chip are optically pumped, which is beneficial to increasing the pump area and improving the conversion efficiency. The DBR-free design avoids the blockage of the pump light caused by the DBR and also avoids the blockage of the pump light caused by the nonlinear crystal 102. The heat dissipation structure 103 quickly conducts the heat generated by the gain chip 107 to the highly heat-dissipating top sidewall, realizing the rapid heat conduction, which is beneficial to improving the stability of the optically pumped semiconductor laser integrated with the frequency conversion crystal. And 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 to improving the flexibility of setting the cavity length of the resonant cavity.

[0024] 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. A plurality of pump units 104 are disposed on the hemispherical inner wall, and the number of layers of the pump units 104 arranged in an annular pattern on the outer periphery of the reflector 105 is multiple layers. Among the adjacent two layers of pump units 104, the pump units 104 located in different layers are staggered from each other. The plurality of pump units 104 are arranged in a spherical shape, and the light output direction of the pump units 104 faces the gain chip 107, which is beneficial to realizing uniform optical pumping of the gain chip 107.

[0025] 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.

[0026] In some embodiments, 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. The materials of the top sidewall, the bottom sidewall, and the annular sidewall all include high-purity copper. Using high-purity copper is beneficial to ensuring that the top sidewall, the bottom sidewall, and the annular sidewall all have excellent heat dissipation performance, which is further beneficial to realizing the rapid export of heat and is beneficial to improving the stability of the optically pumped semiconductor laser integrating the frequency conversion crystal.

[0027] In some embodiments, the inner wall of the pumping cavity 101 has a reflective film with a high reflectivity to the pumping light. In this way, it is beneficial to reduce the loss of the pumping light. The pumping light that is not absorbed by the gain chip 107 and irradiates on the inner wall of the pumping cavity 101 can be reflected by the inner wall and then re-injected into the gain chip 107, which is beneficial to improving the conversion efficiency.

[0028] In some embodiments, a metal layer composed of titanium, platinum, and gold is vapor-deposited on the surface of the annular sidewall facing the pumping cavity 101 and the surface of the bottom sidewall facing the pumping cavity 101 for bonding with the pumping unit 104.

[0029] It should be noted that the shape of the inner wall of the light output window connected to the nonlinear crystal 102 matches the shape of the outer circle of the nonlinear crystal 102, the shape of the inner wall of the light output window connected to the output coupling mirror 106 matches the shape of the outer circle of the output coupling mirror 106, and the shape of the inner wall of the light output window connected to the heat dissipation structure 103 matches the shape of the outer circle of the heat dissipation structure 103.

[0030] In some embodiments, the surface of the heat dissipation structure 103 facing the gain chip 107 has a reflective film with a high reflectivity to the pumping light band and an antireflection film with a high transmittance to the output light band. In this way, it is beneficial to alleviate the influence of the heat dissipation structure 103 on the transmission of the output light into the nonlinear crystal 102, and it is beneficial to ensure that the pumping light is reflected by the heat dissipation structure 103 into the gain chip 107 or the inner wall of the pumping cavity 101, avoiding the leakage of the pumping light.

[0031] In some embodiments, the surface of the heat dissipation structure 103 facing the nonlinear crystal 102 has a reflective film with a high reflectivity to the second harmonic generation light. In this way, it is beneficial to avoid the second harmonic generation light from leaking into the pumping cavity 101 through the heat dissipation structure 103.

[0032] In some embodiments, the side surface of the heat dissipation structure 103 and the inner wall surface of the light output window are in surface contact. In this way, it is beneficial to improve the heat conductivity between the heat dissipation structure 103 and the top sidewall, and further beneficial to realizing the rapid export of the heat of the gain chip 107.

[0033] In some embodiments, the heat dissipation structure 103 is made of a light-transmitting material, and the material of the heat dissipation structure 103 includes diamond or sapphire. In this way, the heat of the gain chip 107 can be quickly dissipated by the heat dissipation structure 103, and the heat dissipation structure 103 is also prevented from blocking the transmission of the output light. In other embodiments, the material of the output coupling mirror 106 may also include other transparent high-thermal-conductivity materials, such as quartz, glass, infrared silicon, calcium fluoride, or magnesium fluoride, etc.

[0034] In some embodiments, the surface of the output coupling mirror 106 facing the nonlinear crystal 102 has a reflective film with a high reflectivity for the output light band and an antireflection film with a high transmittance for the second harmonic generation light. In this way, not only is the output light prevented from overflowing from the output coupling mirror 106, but also the optical loss of the second harmonic generation light emitted from the output coupling mirror 106 is reduced.

[0035] Specifically, according to the spot size, output power, and other performance requirements of the output of the optically pumped semiconductor laser integrating the frequency conversion crystal, the type and parameters of the output coupling mirror 106 can be adjusted, and the cavity length can be controlled by controlling the distance between the output coupling mirror 106 and the mirror 105. The types of the output coupling mirror 106 include but are not limited to plane mirrors, plano-concave mirrors, plano-convex mirrors, and aspherical mirrors, etc.

[0036] 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 second harmonic generation, 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 self-frequency doubling crystals, etc.

[0037] Specifically, the position of the nonlinear crystal 102 can be adjusted according to the spot distribution requirements in the resonant cavity.

[0038] It should be noted that the mirror 105 in the present invention is a mirror 105 that has a high reflectivity for both the pump light band and the output light band. The material of the mirror 105 includes but is not limited to glass, diamond, sapphire, etc. The mirror 105 and the output coupling mirror 106 form a resonant cavity, enabling the output light mode to oscillate in the cavity and obtaining periodic gain. According to the spot size, output power, and other performance requirements of the output light required by the optically pumped semiconductor laser integrating the frequency conversion crystal, the type and parameters of the mirror 105 can be adjusted. The types of the mirror 105 include but are not limited to plane mirrors, plano-concave mirrors, plano-convex mirrors, and aspherical mirrors, etc.

[0039] In some embodiments, the pumping unit 104 is a surface-emitting semiconductor laser, the gain chip 107 is a gain chip of a vertical external cavity surface-emitting semiconductor laser. The gain chip 107 includes an active region, and the active region includes a plurality of quantum well layers and a plurality of barrier layers. The plurality of quantum well layers are arranged at intervals, and there is a barrier layer on each side of each quantum well 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. In this way, it can be ensured that the pump light absorption layer in the gain chip has a relatively large thickness, thereby improving the absorption efficiency of the gain chip for pump light.

[0040] It should be noted that the gain chip 107 is not provided with distributed Bragg reflector (DBR) structures on both sides, and the entire epitaxial structure of the gain chip 107 does not need to be doped, which is easy to fabricate. The quantum wells in the active region of the gain chip 107 can be selected in terms of materials and designed in terms of components according to the required wavelength. The barrier layer is thickened as the pump light absorption layer, improving the absorption and conversion efficiency of pump light.

[0041] The gain chip of the vertical external cavity surface-emitting semiconductor laser can select a material system according to the band requirements of the output light. For example, if the required laser wavelength is in the range of 600 nm to 1200 nm, the gain chip 107 of the vertical external cavity surface-emitting semiconductor laser can select a gallium arsenide material system; if the required laser wavelength is in the range of 1300 nm to 1700 nm, the gain chip of the vertical external cavity surface-emitting semiconductor laser can select an indium phosphide material system.

[0042] The surface-emitting semiconductor laser can select a material system according to the band requirements of the required pump light. For example, if the required pump light wavelength is in the range of 600 nm to 1200 nm, the surface-emitting semiconductor laser can select a gallium arsenide material system; if the required pump light wavelength is in the range of 1300 nm to 1700 nm, the surface-emitting semiconductor laser can select an indium phosphide material system.

[0043] In some embodiments, in the direction perpendicular to the heat dissipation structure 103 and pointing to the output coupling mirror 106, the size of the interval region between the heat dissipation structure 103 and the nonlinear crystal 102 gradually increases from the heat dissipation structure 103 to the nonlinear crystal 102. In this way, it is beneficial to achieve good heat dissipation.

[0044] It should be noted that the top side wall, the bottom side wall and the annular side wall form a high thermal conductivity housing. The outer shape of the high thermal conductivity housing 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 housing can be in the range of 30 mm to 500 mm. The radius of curvature of the hemispherical inner wall can be in the range of 5 mm to 400 mm. The height of the interval region 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 interval region between the nonlinear crystal 102 and the heat dissipation structure 103 can be in the range of 5 mm to 100 mm.

[0045] 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. The side length of the square cross-section can be in the range of 1 mm to 40 mm. The reflectivity of the reflection film thereon for the pump light band is greater than 95%. The reflectivity of the second harmonic generation light reflection film is greater than 95%. The transmittance of the antireflection film thereon for the output light band is greater than 95%.

[0046] In a specific embodiment, the output coupling mirror 106 is a plano-concave mirror made of K9 glass. The output coupling mirror 106 has a second harmonic generation light output region 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 radius of curvature of the output coupling mirror 106 is in the range of 10 mm to 5000 mm. The reflectivity of the reflection film on the surface of the output coupling mirror 106 for the output light is in the range of 85% to 99.9%. The transmittance of the antireflection film of the output coupling mirror 106 for the second harmonic generation light is greater than 95%.

[0047] In a specific embodiment, the mirror 105 is a plane mirror made of K9 glass. The thickness of the mirror 105 can be in the range of 1 mm to 10 mm. The diameter of the mirror 105 is in the range of 1 mm to 40 mm. The reflectivity of the reflection film thereon for the pump light band is greater than 99.9%.

[0048] 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 in the range of 0 to 0.2. The material of the quantum well layer can be InGaAs, where the In component can be in the range of 0 to 0.5. The thickness of the barrier layer can be in the range of 20 nm to 200 nm, and the thickness of the quantum well layer can be in the range of 1 nm to 20 nm. The corresponding emission wavelength band of the gain chip 107 can be in 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 in the range of 10 nm to 800 nm.

[0049] 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 of 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 in 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 in the range of 20 nm to 200 nm, and the thickness of the quantum well layer can be in 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 in 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 limiting layer can be in the range of 20 nm to 1000 nm.

[0050] It should be noted that, on the premise of meeting the heat dissipation requirements and thermal stability, the higher the arrangement density of the pumping units on the inner wall of the pumping cavity, the better, and the arrangement mode of the pumping units is not limited.

[0051] In some examples, the basic parameters of the pumping units are as follows: the wavelength is in the range of 750 nm to 1500 nm, preferably 808 nm or 940 nm, 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 0.01 W to 100 W, which can be in continuous or pulsed mode, preferably the single-point output power is in the range of 0.1 W to 1 W. In this way, the thermal effect and the light intensity requirements can be balanced; the diameter of the pumping units can be in the range of 2 mm to 8 mm.

[0052] In some examples, the spacing between the pumping units is greater than 1.2 times the diameter of the pumping units. In this way, it is beneficial to reduce thermal crosstalk.

[0053] The optically pumped semiconductor laser integrating a frequency conversion crystal provided by the above embodiments realizes intracavity frequency conversion by integrating a nonlinear crystal 102 in the resonant cavity. The bottom-pumped and side-pumped gain chip 107 without DBR is adopted to avoid the interference of the nonlinear crystal 102 on the injection of pumping light, increase the thickness of the pumping light absorption layer of the gain chip 107, and overall improve the absorption efficiency of the gain chip 107 for the pumping light, and a compact frequency-converted optically pumped vertical external cavity semiconductor laser module can be realized. And a plurality of pumping units 104 are densely arranged on the inner wall of the pumping cavity, which is beneficial to improving the pumping power. The inner wall of the pumping cavity is evaporated with a pumping light reflection layer, so that the pumping light oscillates repeatedly on the inner wall of the pumping cavity, and the unabsorbed pumping light passes through the gain chip 107 multiple times, which is beneficial to improving the absorption efficiency of the pumping light.

[0054] It should be understood that various forms of the processes shown above can be used, with steps reordered, added or deleted. For example, the steps recorded in the disclosure of the present invention can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solutions disclosed in the present invention can be achieved, and no limitation is made herein.

[0055] The above specific implementation manners do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An optically pumped semiconductor laser with integrated frequency conversion crystal, characterized in that: include: A pump cavity, wherein the pump cavity 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, 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 are arranged in the light exit window, wherein the heat dissipation structure, the nonlinear crystal and the output coupling mirror are arranged in sequence in the light exit window in a direction away from the pump cavity; A gain chip is arranged 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, wherein the reflector is arranged on a 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; A plurality of pump units are provided 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 plurality of pump units are arranged on the periphery of the reflector, and the plurality of pump units are used to emit pump light to the bottom surface and the side surface of the gain chip.

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 form 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, pump units located in different layers are staggered with each other.

3. The optically pumped semiconductor laser with integrated frequency conversion crystal according to claim 1 or 2, characterized in that: The top side wall, the bottom side wall and the annular side wall are an integrally formed structure, and the materials of the top side wall, the bottom side wall and the annular side wall are the same, and the materials of the top side wall, the bottom side wall and the annular side wall all include 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 has a reflective film with high reflectivity for the pump light band and an anti-reflective 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.

5. The optically pumped semiconductor laser with integrated frequency conversion crystal according to claim 1 or 4, characterized in that: The side surface of the heat dissipation structure is in surface contact with the inner wall surface of the light exit window.

6. 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.

7. 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 has a reflection film with high reflectivity for the output light band and an anti-reflection film with high transmittance for the doubled frequency light.

8. 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, 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.

9. 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.

10. The optically pumped semiconductor laser integrated with a frequency conversion crystal according to claim 1, characterized in that: The inner wall of the pump cavity has a reflective film with high reflectivity to the pump light.

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