Pump temperature-control-free compact all-solid-state laser

Abstract

The invention discloses a pumping temperature-control-free compact all-solid-state laser, and belongs to the technical field of solid-state lasers, the pumping temperature-control-free compact all-solid-state laser comprises an LD array, a coupling lens and a gain crystal which are sequentially arranged in the light path direction, laser emitted by the LD array comprises pumping light and signal light, and the transmission paths of the pumping light and the signal light in the gain crystal are the same; the gain crystal comprises a frame-shaped area defined by a first plane, a second plane, a third plane, a fourth plane, a fifth plane and a sixth plane, and light emitted by the LD array is totally reflected and output in the frame-shaped area. The single-wavelength pump light is utilized to carry out total reflection transmission in the polygonal gain crystal, the absorption length of the pump light is greatly increased, temperature-control-free control over the LD array module within the wide temperature range of-45 DEG C to 60 DEG C can be achieved, and the light-light conversion efficiency and the light beam quality of the laser can be improved through the collinear transmission form of the pump light and the signal light.

Description

Technical Field

[0001] The invention belongs to the technical field of solid-state lasers, and in particular relates to a pump-free temperature-control compact all-solid-state laser. Background Art

[0002] Solid-state laser is a laser that uses solid gain medium. It has the characteristics of high energy output, good beam quality, high stability and reliability, small size and light weight. It can be widely used in industrial processing, medical field, scientific research, military field and communication field.

[0003] With the rapid development of various laser devices and technologies, the laser field is developing towards compact size, high conversion efficiency and high beam quality. Current high-energy pulse lasers generally have some problems due to the existence of high-gain pumping. Since solid-state lasers need to use slab crystals, this will greatly introduce amplified spontaneous radiation effects and self-excited oscillation effects; secondly, it is difficult for the pump light and signal light to obtain a large mode match, resulting in low light-to-light conversion efficiency and poor beam quality of the laser; secondly, when the ambient temperature changes, it is usually necessary to use TEC (thermoelectric cooler) to accurately control the temperature of the semiconductor laser, and the TEC itself has low temperature control efficiency and generates additional heat during operation, which together with the waste heat of the laser itself will affect the stability of the laser. Summary of the invention

[0004] In view of one or more of the above defects or improvement needs of the prior art, the present invention provides a pump-free temperature-controlled compact all-solid-state laser to solve the problems of low light-to-light conversion efficiency, poor beam quality and the need to control the operating temperature of existing laser devices.

[0005] To achieve the above object, the present invention provides a pump temperature-control-free compact all-solid-state laser, comprising: An LD array, a coupling lens and a gain crystal are sequentially arranged along the optical path direction; The gain crystal includes a frame-shaped area surrounded by a first plane, a second plane, a third plane, a fourth plane, a fifth plane and a sixth plane, wherein the second plane, the third plane, the fourth plane and the sixth plane are arranged non-parallel to each other; The light emitted by the LD array is totally reflected and transmitted in the frame-shaped area, and the first plane and the third plane are arranged toward the coupling lens, and the light emitted by the LD array enters the gain crystal via the first plane and is arranged via the third plane; the laser emitted by the LD array includes pump light and signal light, and the pump light and the signal light have the same transmission path in the gain crystal.

[0006] As a further improvement of the present invention, the gain crystal is bonded by an undoped crystal and a polygonal slab gain crystal, wherein the undoped crystal is one of yttrium aluminum garnet or yttrium vanadate crystal, and the polygonal slab gain crystal is one of neodymium-doped yttrium aluminum garnet crystal or neodymium-doped yttrium vanadate crystal, and the first plane is located on the undoped crystal.

[0007] As a further improvement of the present invention, the gain crystal is provided with a seventh face and an eighth face on both sides of the optical path direction, respectively, and the seventh face and the eighth face are bonded with Sm:YAG crystals on the sides away from each other, and the size of the Sm:YAG crystal is the same as the size of the seventh face and the eighth face.

[0008] As a further improvement of the present invention, the thickness of the Sm:YAG crystal is greater than 5 mm.

[0009] As a further improvement of the present invention, the first plane is the incident plane, the fifth plane is the reflection plane, the first plane is coated with a 0° anti-reflection film of 800~840nm, and the fifth plane is coated with a 20~60° high-reflection film of 810~840nm.

[0010] As a further improvement of the present invention, the first surface is an incident surface, the second surface, the fourth surface, the fifth surface and the sixth surface are reflection surfaces, and the third surface is an exit surface; The second plane, the fourth plane and the fifth plane are all coated with a 1064nm 20-60° high reflection film, and the third plane is coated with a 1064nm 0° partial reflection film.

[0011] As a further improvement of the present invention, the LD array outputs pump light energy greater than 5J, and when the operating temperature is 8°C, the pump light output center wavelength is 818nm.

[0012] As a further improvement of the present invention, the length of the second plane on the surface where the frame area is located is 301.6 mm, the length of the third plane on the surface where the frame area is located is 52.2 mm, the length of the fourth plane on the surface where the frame area is located is 93.0 mm, and the length of the fifth plane on the surface where the frame area is located is 79.4 mm.

[0013] As a further improvement of the present invention, the pump light is single-wavelength light.

[0014] The above-mentioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0015] In general, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects: (1) The present invention adopts a polygonal gain crystal end face as the resonant cavity, avoiding the combination of multiple resonant cavity mirrors and gain crystals in traditional lasers, thereby greatly reducing the overall volume of the laser. Secondly, the present application utilizes single-wavelength pump light to perform total reflection transmission in the polygonal gain crystal, which greatly increases the absorption length of the pump light and enables temperature-free control of the LD array module within a wide temperature range of -45 to 60°C. In addition, the co-linear transmission of the pump light and the signal light can improve the light-to-light conversion efficiency and beam quality of the laser.

[0016] (2) The pumped temperature-free compact all-solid-state laser of the present invention has a gain crystal bonded by a non-doped crystal and a polygonal slab gain crystal, and the non-doped crystal is a yttrium aluminum garnet or a yttrium vanadate crystal, and the polygonal slab gain crystal is a neodymium-doped yttrium aluminum garnet crystal or a neodymium-doped yttrium vanadate crystal. In the present application, the first plane of the gain crystal is located on the non-doped crystal. The non-doped crystal has good thermal stability, which can prevent the pump light from directly irradiating the polygonal slab gain crystal, reduce the thermal effect of the pump light, suppress self-excited oscillation and amplify the spontaneous radiation effect, and ensure the stable operation of the laser.

[0017] (3) The present invention provides a compact all-solid-state laser that does not require temperature control. By arranging Sm:YAG crystals on both sides of the seventh and eighth planes, the Sm:YAG crystals can also suppress amplified spontaneous radiation and self-excited oscillation effects to ensure stable operation of the laser. At the same time, the present invention selectively coats each surface of the gain crystal to suppress amplified spontaneous radiation and self-excited oscillation effects, and realizes total reflection transmission of the pump light, increases the absorption length of the pump light, and realizes temperature-free control of the LD array module.

[0018] (4) The pump-free temperature-control-free compact all-solid-state laser of the present invention adopts a bonding design of a non-doped crystal and a polygonal slab gain crystal through a special shape and size design. There is no need to plate a film on the gain crystal to suppress amplified spontaneous radiation and self-excited oscillation effects. The amplified spontaneous radiation and self-excited oscillation effects can be greatly suppressed by relying solely on the gain crystal structure design. Secondly, the present application adopts a single gain crystal structure, omitting the combination of multiple resonant cavities in conventional solid-state lasers, greatly reducing the size of the laser. A single wavelength is used as the pump source, which can achieve operation at an ambient temperature of -45°C to 60°C without temperature control. At the same time, the pump light and the signal light are matched with the gain crystal shape, and have good mode matching in the gain crystal, which greatly improves the light-to-light conversion efficiency and beam quality of the solid-state laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the overall structure of a pump temperature-control-free compact all-solid-state laser in an embodiment of the present invention; Figure 2 is a schematic diagram of the side structure of a gain crystal in an embodiment of the present invention; Figure 3 is a schematic diagram of the overall structure of a gain crystal in an embodiment of the present invention; Figure 4 Schematic diagram of the structure and size of the gain crystal in the embodiment of the present invention.

[0020] In all the drawings, the same reference numerals represent the same technical features, specifically: 1. LD array; 2. Coupling lens; 3. Gain crystal; 4. Pump light; 5. Signal light; 301, non-doped crystal; 302, polygonal slab gain crystal; 3011, first plane; 3012, second plane; 3013, third plane; 3014, fourth plane; 3015, fifth plane; 3016, sixth plane; 3017, seventh plane; 3018, eighth plane. DETAILED DESCRIPTION

[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 in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] In the description of the present invention, it should be understood that, unless otherwise specified, terms such as “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0023] In addition, unless otherwise specified, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0024] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] Example: See also Figures 1 to 4 The pumped temperature-free compact all-solid-state laser in the preferred embodiment of the present invention comprises an LD array 1, a coupling lens 2 and a gain crystal 3 which are sequentially arranged along the optical path direction; wherein the gain crystal 3 comprises a frame-shaped area formed by a first plane 3011, a second plane 3012, a third plane 3013, a fourth plane 3014, a fifth plane 3015 and a sixth plane 3016, wherein the second plane 3012, the third plane 3013, the fourth plane 3014 and the sixth plane 3016 are arranged non-parallel to each other; secondly, the light emitted by the LD array 1 is transmitted by total reflection in the frame-shaped area, the first plane 3011 and the third plane 3013 are arranged toward the coupling lens 2, the light emitted by the LD array 1 enters the gain crystal 3 via the first plane 3011, and is emitted via the third plane 3013; and the laser emitted by the LD array 1 comprises a pump light 4 and a signal light 5, and the transmission paths of the pump light 4 and the signal light 5 in the gain crystal 3 are the same.

[0027] The pump temperature-free compact all-solid-state laser in the present application adopts the end face of the polygonal structure gain crystal 3 as the resonant cavity, avoiding the combination of multiple resonant cavity mirrors and the gain crystal 3 of the traditional laser, and greatly reducing the overall volume of the laser; secondly, the present application uses a single-wavelength pump light 4 to perform total reflection transmission in the polygonal gain crystal 3, which greatly increases the absorption length of the pump light 4, and can achieve temperature-free control of the LD array 1 module within a wide temperature range of -45°C to 60°C, and the co-linear transmission form of the pump light 4 and the signal light 5, such as Figure 1 As shown, the black solid line in the figure is the pump light 4, and the gray dotted area is the signal light 5. The two are transmitted on the same line, which can improve the light-to-light conversion efficiency and beam quality of the laser.

[0028] Specifically, the optical path direction in the present application refers to the transmission path of the light emitted from the LD array 1, which is coupled by the coupling lens 2 and then transmitted to the gain crystal 3, and then totally reflected in the gain crystal 3, and the pump light 4 and the signal light 5 resonate in the gain crystal 3, and finally output. The LD (laser diode) array 1 in the present application is composed of a plurality of laser diodes arranged and combined in a certain manner, and is mainly used to generate lasers. The coupling lens 2 is mainly used to compress the fast axis and slow axis of the pump light 4 emitted by the LD array 1, so that the pump light 4 is a collimated laser, which can enter the inside of the gain crystal 3 after being vertically irradiated onto the first plane 3011. Preferably, the coupling lens 2 is coated with an anti-reflection film of 800~840nm to collimate the fast axis and slow axis of the pump laser, and after the pump light 4 is collimated, its spot size is 150nm. At the same time, the present application sets the gain crystal 3 as a special-shaped structure, and increases the light transmission path under the same size by adjusting the transmission path of the pump light 4 in the gain crystal 3, so as to suppress the amplified spontaneous radiation and self-excited oscillation effects. Accordingly, due to the suppression of spontaneous radiation and self-excited oscillation effects, the solid-state laser of the present application does not need to use TEC for temperature suppression, thus avoiding the influence of TEC operation on the solid-state laser and ensuring the stable operation of the solid-state laser.

[0029] Further, as one embodiment of the present invention, the gain crystal 3 in the present application is formed by bonding a non-doped crystal 301 and a polygonal slab gain crystal 302, wherein the non-doped crystal 301 is one of yttrium aluminum garnet or yttrium vanadate crystal, the polygonal slab gain crystal 302 is one of neodymium-doped yttrium aluminum garnet crystal or neodymium-doped yttrium vanadate crystal, and the first plane 3011 is located on the non-doped crystal 301. In the present application, the laser coupled from the coupling lens 2 is directly irradiated onto the gain crystal 3. In order to avoid damage to the gain crystal 3 by the thermal effect of the laser, the present application sets the gain crystal 3 in the bonding form of the non-doped crystal 301 and the polygonal slab gain crystal 302. By selecting the non-doped crystal 301 at the incident front end (first plane 3011) of the laser, the thermal effect of the laser is reduced by the yttrium aluminum garnet or yttrium vanadate crystal, so as to ensure the stable operation of the solid-state laser.

[0030] Further, as one of the embodiments of the present invention, the gain crystal 3 in the present application is provided with a seventh plane 3017 and an eighth plane 3018 on both sides of the optical path direction, and the seventh plane 3017 and the eighth plane 3018 are respectively bonded with Sm:YAG (samarium-doped yttrium aluminum garnet) crystals on the opposite sides, and the size of the Sm:YAG crystal is the same as the size of the seventh plane 3017 and the eighth plane 3018. The laser also has a certain size along the width direction. In order to suppress the radiation effect of the laser along the width direction, the present application corresponds to bonding Sm:YAG crystals on the seventh plane 3017 and the eighth plane 3018 to suppress self-excited oscillation and amplify spontaneous radiation effects. Further preferably, the thickness of the Sm:YAG crystal here is greater than 5 mm, and the Sm:YAG crystal at this thickness can enable the solid-state laser to achieve temperature control-free in a wide temperature range of -45°C to 60°C.

[0031] Further, as one of the embodiments of the present invention, the first plane 3011 in the present application is coated with a 0° anti-reflection film of 800~840nm, and the fifth plane 3015 is coated with a 20~60° high-reflection film of 810~840nm. In the present application, the output center wavelength of the pump light 4 is 818nm. By coating the first plane 3011 with a 0° anti-reflection film of 800~840nm, the absorption of the pump light 4 by the gain crystal 3 is increased. At the same time, the 20~60° high-reflection film of 810~840nm on the fifth plane 3015 can fully reflect the pump light 4, increase the transmission path of the pump light 4 in the gain crystal 3, so that the pump light 4 is transmitted in the gain crystal 3 according to the set path. Specifically, the anti-reflection film here refers to a reflectivity of less than 1% for a specific wavelength of light, and the high-reflection film refers to a reflectivity of more than 99% for a specific wavelength of light.

[0032] Further, as one embodiment of the present invention, the first plane 3011 in the present application is the incident plane, the second plane 3012, the fourth plane 3014, the fifth plane 3015 and the sixth plane 3016 are reflection planes, and the third plane 3013 is the exit plane; wherein the second plane 3012, the fourth plane 3014, the fifth plane 3015 and the sixth plane 3016 are coated with a 1064nm 20~60° high reflection film, and the third plane 3013 is coated with a 1064nm 0° partial reflection film. Specifically, the present application needs to ensure that the pump light 4 and the signal light 5 are fully reflected and transmitted in the gain crystal 3, so the second plane 3012, the fourth plane 3014, the fifth plane 3015 and the sixth plane 3016 are coated with a 1064nm 20~60° high-reflection film, so that the signal light 5 propagating at a specific angle can be fully reflected and transmitted in the gain crystal 3; the third plane 3013 is a 1064nm 0° partial reflection film, and the third plane 3013 is the laser outlet. The laser is output from the third plane 3013 after resonating in the gain crystal 3.

[0033] Furthermore, as one embodiment of the present invention, the LD array 1 in the present application outputs a pump light 4 whose energy is greater than 5 J, and when the operating temperature is 8° C., the output center wavelength of the pump light 4 is 818 nm.

[0034] Further, as one embodiment of the present invention, Figure 4 As shown, the length of the second plane 3012 in the present application on the plane where the frame area is located is 301.6 mm, the length of the third plane 3013 on the plane where the frame area is located is 52.2 mm, the length of the fourth plane 3014 on the plane where the frame area is located is 93.0 mm, and the length of the fifth plane 3015 on the plane where the frame area is located is 79.4 mm. Specifically, the non-doped crystal 301 in the present application is a triangular sheet structure, and the non-doped crystal 301 is attached to the side of the polygonal slat gain crystal 302. With the sixth plane 3016 as the horizontal reference, the angle θ1 between the first plane 3011 of the non-doped crystal 301 and the sixth plane 3016 is 58.2°; the angle θ2 between the second plane 3012 and the vertical direction of the polygonal slat gain crystal 302 is 80.6°, and the angle θ3 between the third plane 3013 and the fourth plane 3014 is 71.4°. The length L7 of the first plane 3011 is 154.3 mm, the length L1 of the second plane 3012 is 301.6 mm, the length L2 of the third plane 3013 is 52.2 mm, the length L3 of the fourth plane 3014 is 93.0 mm, the length L4 of the fifth plane 3015 is 79.4 mm, and the sixth plane 3016 is formed by bonding the non-doped crystal 301 and the polygonal slab gain crystal 302, wherein the length L5 of the polygonal slab gain crystal 302 at the sixth plane 3016 is 388.5 mm, and the length L6 of the non-doped crystal 301 at the sixth plane 3016 is 81.3 mm, and the length of each plane here refers to the length of the plane where the frame area is located. The present application designs the shape and size of the gain crystal 3 so that the pump light 4 and the signal light 5 can be fully reflected and propagated in the gain crystal 3, thereby suppressing the self-excited oscillation and amplified spontaneous radiation effect inside the crystal under high-energy pumping.

[0035] Furthermore, the pump light 4 emitted by the LD array 1 in the present application is a single-wavelength light. The solid-state laser in the present application can achieve normal operation at an ambient temperature of -45°C to 60°C without temperature control by selecting a single wavelength as a pump source and coordinating with the design of the gain crystal 3.

[0036] The pump temperature-control-free compact all-solid-state laser of the present invention adopts a bonding design form of a non-doped crystal 301 and a polygonal slab gain crystal 302 through a design of special shape and size. There is no need to plate a film on the gain crystal 3 to suppress amplified spontaneous radiation and self-excited oscillation effects. The amplified spontaneous radiation and self-excited oscillation effects can be greatly suppressed by relying solely on the structural design of the gain crystal 3. Secondly, the present application adopts a single gain crystal 3 structure, omitting the combination of multiple resonant cavities in conventional solid-state lasers, greatly reducing the size of the laser. A single wavelength is used as a pump source, and operation can be achieved at an ambient temperature of -45°C to 60°C without temperature control. At the same time, the pump light 4 and the signal light 5 cooperate with the shape of the gain crystal 3, and have good mode matching in the gain crystal 3, which greatly improves the light-to-light conversion efficiency and beam quality of the solid-state laser.

[0037] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pump temperature-free compact all-solid-state laser, characterized in that: include: An LD array, a coupling lens and a gain crystal are sequentially arranged along the optical path direction; The gain crystal includes a frame-shaped area surrounded by a first plane, a second plane, a third plane, a fourth plane, a fifth plane and a sixth plane, wherein the second plane, the third plane, the fourth plane and the sixth plane are arranged non-parallel to each other; The light emitted by the LD array is totally reflected and transmitted in the frame-shaped area, and the first plane and the third plane are arranged toward the coupling lens. The light emitted by the LD array enters the gain crystal through the first plane and is emitted through the third plane. The laser emitted by the LD array includes pump light and signal light, and the pump light and the signal light have the same transmission path in the gain crystal.

2. The pump temperature-control-free compact all-solid-state laser according to claim 1, characterized in that: The gain crystal is formed by bonding an undoped crystal and a polygonal slab gain crystal, wherein the undoped crystal is one of yttrium aluminum garnet and yttrium vanadate crystal, and the polygonal slab gain crystal is one of neodymium-doped yttrium aluminum garnet crystal and neodymium-doped yttrium vanadate crystal, and the first plane is located on the undoped crystal.

3. The pump temperature-free compact all-solid-state laser according to claim 1, characterized in that: The gain crystal is provided with a seventh plane and an eighth plane on both sides of the optical path direction, respectively. The seventh plane and the eighth plane are bonded with Sm:YAG crystals on the sides away from each other, and the size of the Sm:YAG crystal is the same as that of the seventh plane and the eighth plane.

4. The pump temperature-control-free compact all-solid-state laser according to claim 3, characterized in that: The thickness of the Sm:YAG crystal is greater than 5 mm.

5. The pump temperature-control-free compact all-solid-state laser according to claim 1, characterized in that: The first plane is an incident plane, the fifth plane is a reflective plane, the first plane is coated with a 0° anti-reflection film of 800-840nm, and the fifth plane is coated with a 20-60° high-reflection film of 810-840nm.

6. The pump temperature-control-free compact all-solid-state laser according to claim 1, characterized in that: The first plane is an incident plane, the second plane, the fourth plane, the fifth plane and the sixth plane are reflection planes, and the third plane is an exit plane; The second plane, the fourth plane, the fifth plane and the sixth plane are all coated with a 1064nm 20-60° high reflection film, and the third plane is coated with a 1064nm 0° partial reflection film.

7. The pump temperature-control-free compact all-solid-state laser according to claim 1, characterized in that: The LD array outputs pump light energy greater than 5J, and when the operating temperature is 8°C, the pump light output center wavelength is 818nm.

8. The pump temperature-control-free compact all-solid-state laser according to claim 1, characterized in that: The length of the second plane on the surface where the frame area is located is 301.6 mm, the length of the third plane on the surface where the frame area is located is 52.2 mm, the length of the fourth plane on the surface where the frame area is located is 93.0 mm, and the length of the fifth plane on the surface where the frame area is located is 79.4 mm.

9. The pump temperature-control-free compact all-solid-state laser according to claim 1, characterized in that: The pump light is single-wavelength light.

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