JPH05211361A - Semiconductor laser-pumping solid laser device - Google Patents

Abstract

PURPOSE:To provide a semiconductor laser-pumping solid laser device which is comparatively simple in structure, stable in oscillation output, and can be easily enhanced in output power. CONSTITUTION:A pumping semiconductor laser device 3 and a solid laser medium 2 are housed in a case 2, coolant 7 of insulating transparent liquid is filled into the case 1 so as to come into contact with a part of the pumping semiconductor laser device 3 and the solid laser medium 2, and a temperature control device 6 is provided to keep coolant 7 at a certain temperature where the oscillation wavelength L0 of the pumping semiconductor laser device 3 is set equal to an absorption wavelength of the solid laser medium 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser pumped solid-state laser device that uses laser light emitted from a semiconductor laser device as pumping light.

[0002]

2. Description of the Related Art A semiconductor laser pumped solid-state laser device that uses laser light emitted from a semiconductor laser device as pumping light is such that the wavelength of the pumping laser light emitted from the pumping semiconductor laser device is equal to the absorption wavelength of the solid-state laser medium. If they do not match, the oscillation efficiency drops significantly. Here, the oscillation wavelength of the pumping semiconductor laser device changes depending on the temperature of the pumping semiconductor laser device. Therefore, in order to match the oscillation wavelength of the pumping semiconductor laser device with the absorption wavelength of the solid-state laser medium, the temperature of the pumping semiconductor laser device must be accurately maintained at a predetermined temperature.

As a method of maintaining the temperature of the pumping semiconductor laser device at a predetermined temperature, a method of holding the substrate on which the light emitting portion of the pumping semiconductor laser device is mounted at a constant temperature by using a Peltier element is generally used. (See, eg, US Pat. No. 4,739,507). However, when a large number of pumping semiconductor laser devices are used to obtain a high output, a large number of Peltier elements and their driving devices are required,
The device becomes complicated and expensive, which is not realistic. Therefore, in such a case, a method of mounting a radiator on a substrate on which a light emitting portion of a semiconductor laser device for excitation is mounted and cooling water by passing cooling water through the radiator (Advaced Solid-St
ate Laser 1991 technical digest pdp8-1).

[0004]

By the way, the cooling method of the pumping semiconductor laser device in the above-mentioned conventional method is as follows.
The temperature of the substrate on which the pumping semiconductor laser device is fixed is kept constant, and heat is exchanged by heat conduction at the contact surface between the substrate surface and the semiconductor laser device to indirectly determine the temperature of the light emitting portion of the semiconductor laser device. It was the one trying to reach the temperature. However, in such an indirect cooling method, thermal resistance is generated at the contact surface, so that there is a certain limit in improving the efficiency and stability of temperature control. For example, output is 10W
When the temperature of the semiconductor laser device is to be driven at 20 ° C., the semiconductor laser device generates heat of about 30 W, and the thermal resistance of the contact surface between the semiconductor laser device and the substrate is 0.2 ° C./W.
In this case, the temperature of the substrate must be lowered to 14 ° C. If the output of the semiconductor laser device increases, the temperature difference between the semiconductor laser device and the substrate further widens, which is a problem when using a high-output semiconductor laser device.

As described above, in the conventional method, it is indispensable to consider the heat radiation of the semiconductor laser device. Therefore, the structure of the device has many restrictions on the problem of heat, and the output of the usable semiconductor laser device is large. The number of devices that can be arranged is limited, and the structure of the device must be complicated.

Furthermore, since the solid-state laser medium is cooled only from the portion in contact with the portion supporting the solid-state laser medium, heat does not propagate uniformly due to the presence of fine irregularities in the contact portion. In such a case, an irregular temperature distribution is likely to occur inside the solid-state laser medium, which easily causes deterioration of the laser beam quality and deterioration of the solid-state laser medium due to thermal strain.

The present invention has been made under the background described above, and provides a semiconductor laser pumped solid-state laser device which has a stable oscillation output and can easily attain a high output with a relatively simple structure. It is intended to be provided.

[0008]

In order to solve the above problems, the present invention provides (1) a solid-state laser in which a laser beam for pumping emitted from a semiconductor laser device for pumping is arranged in a laser resonator. In a semiconductor laser pumped solid-state laser device for irradiating a medium and exciting the solid-state laser medium to obtain output laser light, the pumping semiconductor laser device and the solid-state laser medium are housed in a container, and Insulating and transparent refrigerant is introduced so that the refrigerant comes into contact with at least a part of the semiconductor laser device for excitation and the solid-state laser medium, and the temperature of the refrigerant is set to the temperature of the semiconductor laser device for excitation. A temperature control device for maintaining the temperature of the pumping semiconductor laser device is provided so that the oscillation wavelength matches the absorption wavelength of the solid-state laser medium.

As a mode of the configuration 1, (2)
In the semiconductor laser pumped solid-state laser device of constitution 1, the refrigerant is a cooling liquid, (3)
In the semiconductor laser pumped solid-state laser device of configuration 1, the refrigerant is a cooling gas, and
(4) In the semiconductor-laser-pumped solid-state laser device of configuration 1, the temperature control device takes out a part of the refrigerant from the container and introduces it, and after returning the temperature to a target temperature, returns it to the container. The configuration is characterized in that it is a circulating type temperature control device.

Further, as modes of configurations 1 to 4, (5)
In the semiconductor laser pumped solid-state laser device according to any one of configurations 1 to 4, the pumping laser light emitted from the pumping semiconductor laser device is irradiated onto the solid-state laser medium from a side surface of the solid-state laser medium. In the semiconductor laser pumped solid-state laser device according to any one of configurations 1 to 4, the pumping laser light emitted from the pumping semiconductor laser device is supplied to the solid-state laser medium. The solid-state laser medium is irradiated from the end faces that are the entrance and exit faces of the resonant laser light.

[0011]

According to the above configuration 1, since the liquid or gas refrigerant can be directly brought into contact with the light emitting portion of the pumping semiconductor laser device to cool it, the pumping semiconductor can be accurately maintained at a predetermined temperature. It is possible to accurately maintain the temperature of the light emitting portion of the laser device at a predetermined temperature. For this reason,
The wavelength fluctuation of the semiconductor laser device can be suppressed, and the output of the excitation light absorbed by the solid-state laser medium can be stabilized. Further, when using a plurality of pumping semiconductor laser devices, it is not necessary to consider the heat radiation method for each semiconductor laser device, the structure of the device can be simplified, and more pumping semiconductor laser devices can be arranged relatively freely. It is possible to secure a space to operate. Furthermore, the solid-state laser medium can be cooled at the same time as the pumping semiconductor laser device by the coolant, and the temperature of the solid-state laser medium can be maintained at a stable temperature. Therefore, it is possible to stably obtain the output of the oscillating laser light and the beam characteristics.

Here, if a cooling liquid having a large heat capacity is used as the refrigerant as in the configuration 2, it can be strongly cooled even when the heat generation amount of the pumping semiconductor laser device or the like is large. By using the cooling gas as the cooling medium, the cooling can be performed relatively easily.

According to the structure 4, since the temperature control device for controlling the temperature of the refrigerant to the predetermined temperature can be provided outside, the structure around the container can be made smaller and more compact.

Further, according to the structure 5, a large number of pumping semiconductor laser devices can be arranged by using the lateral pumping method, and these can be accurately maintained at a predetermined temperature. Can be oscillated.

According to the structure 6, by adopting the end face pumping method, the pumping semiconductor laser device and the solid-state laser device are housed in the container, and both of them can be cooled by the refrigerant, and a simple structure can be obtained. Since the temperature of the pumping semiconductor laser device can be maintained at a predetermined temperature extremely accurately, it is possible to obtain a laser beam having excellent beam characteristics by fully utilizing the characteristics of the end face pumping, and It is possible to obtain an edge-pumped semiconductor laser pumped solid-state laser device that can be formed compactly and compactly.

[0016]

First Embodiment FIG. 1 is a longitudinal sectional view of a semiconductor laser pumped solid-state laser device according to a first embodiment of the present invention, and FIG. 2 is a semiconductor laser pumped solid-state laser device according to the first embodiment of the present invention. FIG. Hereinafter, the first embodiment of the present invention will be described in detail with reference to these drawings. It should be noted that this embodiment is an example in which a cooling liquid is used as a cooling medium and a high-power laser beam is obtained by a side excitation method.

1 and 2, reference numeral 1 is a container, reference numeral 2 is a rod-shaped solid-state laser medium, reference numeral 3 is a pumping semiconductor laser device, reference numeral 4 is a total reflection mirror, reference numeral 5 is an output mirror, and reference numeral 6 is A circulation type temperature control device, reference numeral 7 is a cooling liquid filled in the container 1. The total reflection mirror 4 and the output mirror 5 form a laser resonator.

The container 1 is made of a material such as aluminum or stainless steel, and has a prismatic outer shape, and a cylindrical cavity having a diameter larger than the outer shape of the solid-state laser medium 2 is formed inside along the axis of the prism. This is the storage section 1a. Further, on both end faces that intersect the axis of the prism, circular window portions 1b and 1 having a diameter substantially equal to the diameter of the solid-state laser medium 2 are provided.
c is formed. And these window parts 1b and 1c
Both ends of the solid-state laser medium 2 are sealed by fitting the both ends of the solid-state laser medium 2 in between, inserting the O-ring 1d, and screwing the setscrews 1e into the screw portions formed in these windows. It is designed to be fixed. That is, the solid-state laser medium 2 is arranged along the central axis of the housing portion 1a, and both end surfaces that intersect the optical axis are exposed to the outside.

Further, a part of the inner peripheral surface of the storage portion 1a is projected toward the center over the entire length in the longitudinal direction, and a part of the surface of the projected portion is formed into a flat surface directed toward the center. This is the base portion 1f. Then, five pumping semiconductor laser devices 3 are fixed to the pedestal portion 1f at predetermined intervals so that their respective light emitting portions face the direction of the solid-state laser medium 2. There is.

Furthermore, at both ends in the longitudinal direction of the container 1,
A cooling liquid outflow hole 1g and a cooling liquid inflow hole 1h are provided respectively, one end of a cooling liquid outflow pipe is connected to the cooling liquid outflow hole 1g through a joint fitting 6a, and the cooling liquid inflow hole 1h is connected to the cooling liquid inflow hole 1h. Cooling liquid inflow pipe 6 via joining metal fitting 6c
One end of d is connected. The other ends of the cooling liquid outflow hole 1g and the cooling liquid inflow hole 1h are connected to the cooling liquid introduction port and the cooling liquid discharge port of the circulation type temperature control device 6.

This circulation type temperature control device 6 introduces the cooling liquid from the cooling liquid introduction port, discharges it from the cooling liquid discharge hole, circulates the cooling liquid 7, and circulates the cooling liquid 7, and the temperature of the introduced cooling liquid is constant. It has a built-in temperature controller for controlling.

Further, the inner peripheral surface of the container 1 forming the housing portion 1a is formed into a mirror surface, and is a reflecting surface 1i. The reflection surface 1i is formed by mirror-polishing the inner peripheral surface of the container 1 which forms the storage portion 1a, but may be formed by forming a reflection film of aluminum, silver, gold or the like.

The solid-state laser medium 2 is an Nd: YAG laser rod that oscillates a laser beam having a wavelength of 1064 nm, has a diameter of 3 mmφ and a length of 30 mm. Both end surfaces are flat-polished and reflected by the oscillating laser beam. The prevention film is formed. The light absorption peak wavelength of this solid-state laser medium 2 is 807 nm.

On both sides of the solid-state laser medium 2 in the longitudinal direction and on the outer side of the container 1, the optical axis is common to the solid-state laser medium 2 and both spherical concave concave surfaces serve as reflecting surfaces. The total reflection mirror 4 and the output mirror 5 are arranged to form a laser resonator.

Here, the total reflection mirror 4 is such that the radius of curvature of the concave surface which is the total reflection surface is set to 5 m. Further, the output mirror 5 forms a reflection film made of a dielectric multilayer film on the surface of the concave surface of a glass body having a concave lens shape arranged so that the concave surface faces the laser medium 2 side, and the output laser light L ₁ The transmittance is set to 3%, and by setting the radius of curvature of the concave surface to 5 m, the total reflection mirror 4 constitutes a laser resonator having a resonator length of 100 mm.

The pumping semiconductor laser device 3 is a GaAs semiconductor laser device having an oscillation wavelength of 800 to 820 nm and has an output of 5 W. It is necessary to arrange the five pumping semiconductor laser devices 3 so that the oscillation wavelengths of the respective laser lights are the same when the temperatures are all the same. In this embodiment, five pumping semiconductor laser devices 3 are
Both of them have a temperature of 25 ° C. and an oscillation wavelength of 807 nm. This is the case where Nd: YAG having an absorption peak wavelength of 807 nm is used as the solid-state laser medium 2, but when Nd: YLF having an absorption peak wavelength of 795 nm is used as the solid-state laser medium, the respective temperatures are the same. At this time, a semiconductor laser device having uniform characteristics is selected so that all oscillation wavelengths become 795 nm. The excitation semiconductor laser 3 is driven by the driving device 3a.

As the cooling liquid 7, a transparent and highly insulating liquid is used. In this example, Fluorinert (trade name of 3M Company, USA), which is a kind of fluorocarbon compound and is used as a cooling liquid for semiconductor parts and the like, was used. This Fluorinert has a high transmittance of 90% or more with respect to the light having a wavelength of 807 nm emitted from the excitation semiconductor laser device 3, and has an extremely high dielectric strength of 30 KV.
It is thermally and chemically stable, and does not disturb the operation of the excitation laser device 3 or damage the light emitting portion. Moreover, since it has twice the thermal conductivity of silicone oil, it is optimal as a cooling liquid. Silicon oil may be used as the cooling liquid 7.

In the above-mentioned structure, the circulation type temperature control device 6 holds the cooling liquid 7 at 25 ° C.
To drive the pumping semiconductor laser device 3 to irradiate the solid-state laser medium 2 with the pumping laser beam L ₀ (wavelength: 807 nm) to oscillate the laser beam.
At m, the output has an extremely high value of 3 W, and the output laser light L ₁ having excellent beam characteristics can be obtained. By the way, in order to obtain an equivalent output with a conventional semiconductor laser pumped solid-state laser device, the entire device has a complicated structure such as a water cooling pipe at the base of each pumping semiconductor laser device, and a large size. It was supposed to be. On the other hand, in the above-described embodiment, the structure is extremely simple, and therefore, the device can be made extremely small and compact.

Second Embodiment FIG. 3 is a transverse sectional view of a semiconductor laser pumped solid-state laser device according to a second embodiment of the present invention. The second embodiment will be described in detail below with reference to FIG. Note that this embodiment also uses a cooling liquid as a cooling medium and is based on the side surface excitation method, and since much of the configuration is common to the above-described first embodiment, the same reference numerals are given to the common parts. Omit the description,
Only the points unique to this embodiment will be described below.

In this embodiment, a container 21 is used instead of the container 1 in the first embodiment described above, and
As compared with the case of the embodiment, a larger number of pumping semiconductor laser devices can be attached to obtain a larger output laser beam. That is, container 2
The reference numeral 1 indicates that four pedestal portions 21f corresponding to the pedestal portions 1f in the above-described first embodiment are provided in the storage portion 21a around the central axis of the storage portion 1a.
Five pumping semiconductor laser devices 3 are attached to each 1f, and the solid-state laser medium 2 is pumped by a total of 20 pumping semiconductor laser devices 3.
The other structure is substantially the same as that of the first embodiment. This makes it possible to obtain a very high-power laser beam with an output of 9 W in an extremely stable manner.

Third Embodiment FIG. 4 is a cross sectional view of a semiconductor laser pumped solid state laser device according to a third embodiment of the present invention. The third embodiment will be described in detail below with reference to FIG. Note that this embodiment is the same as the first and second embodiments in that a cooling liquid is used as the cooling medium, but by adopting the end face excitation method as the excitation method, an extremely small and compact structure is achieved. This is an example of obtaining a laser beam having excellent characteristics.

In FIG. 4, reference numeral 31 is a container and reference numeral 32.
Is a rod-shaped solid-state laser medium, 33 is a pumping semiconductor laser device, 34 is a selective reflection film formed on one end face of the solid-state laser medium 32, 35 is an output mirror, and 37 is a container 31. Cooling liquid, reference numeral 38a,
38b is a condenser lens. The selective reflection film 34 and the output mirror 5 form a laser resonator.

The container 31 is made of a material such as aluminum or stainless steel, and has a prismatic outer shape, and a substantially cylindrical cavity having a diameter larger than the outer shape of the solid-state laser medium 2 is formed inside along the axis of the prism. This is the storage portion 31a. Further, one end portion that intersects with the axis of the prism, that is, the right end portion in the figure is formed thick, and the right end portion has a circular shape with a diameter substantially equal to the diameter of the solid-state laser medium 32 along the central axis direction of the prism. Through hole 31b is formed. Then, the solid-state laser medium 32 is inserted into the through hole 31b, and a part of the solid-state laser medium 32 (approximately 1/3 of the entire length) is inserted.
Is disposed so as to project into the storage portion 31a, and the side opposite to the projected side sandwiches the O-ring 31d and the set screw 31e is screwed into the threaded portion formed in the through hole 31d. The right end of the solid-state laser medium 2 is hermetically fixed. That is, the solid-state laser medium 2 is arranged along the central axis of the storage portion 1a, and the left end face of the both end surfaces intersecting the optical axis of the storage portion 1a has the storage portion 3a.
1a, and the right end face is exposed to the outside.

Further, in the housing portion 31a, the pumping semiconductor laser device 33 and the condenser lenses 38a and 38b are sequentially arranged from the left side with the optical axis in common with the solid-state laser medium 32. In this case, the excitation semiconductor laser device 33
Is fixed to the left end surface of the housing portion 31a, and the condenser lenses 38a and 38b are two lens holding frames formed by protruding a ring-shaped part of the inner peripheral surface of the housing portion 31a toward the center. 31j. It should be noted that the lens holding frame 31j is formed with a cooling liquid circulation hole 31k so that the cooling liquid 7 can freely flow in the storage portion 31a.

Further, a cooling liquid outflow hole 31g and a cooling liquid inflow hole 31h are provided at both ends of the container 31 in the longitudinal direction, respectively, and are connected to a circulation type temperature control device (not shown), and the first embodiment is used. Similarly, the cooling liquid 7 can be circulated and maintained at a predetermined temperature (25 ° C.).

The solid-state laser medium 32 has a wavelength of 1064 nm.
Nd: YAG laser rod that oscillates a laser beam having a diameter of 3 mmφ and a length of 5 mm and a wavelength of 80 mm.
It has an absorption peak for light of 7 nm.

A selective reflection film 34 made of a dielectric multilayer film is formed on one end face of the solid laser medium 32, which intersects the optical axis, that is, on the left end face in the drawing. The selective reflection film 34 constitutes a laser resonator together with the output mirror 35, and has a high reflectance of 99.9% or more with respect to the output laser light (L ₁ = 1064 nm), while being excited. Has a property of transmitting 85% or more of the laser light for use (L ₀ = 807 nm). The other end face of the solid-state laser medium 32,
That is, although not shown, the right end face in the figure is provided with a non-reflective coating so that the reflectivity for the output laser beam L ₁ at this end face is 0.5% or less.

The concave surface of the output mirror 35 is the laser medium 32.
A reflective film composed of a dielectric multilayer film is formed on the surface of the concave surface of the glass body in the shape of a concave lens arranged so as to face the side,
The transmittance for the output laser light L ₁ is set to 3%, and the radius of curvature of the concave surface is set to 30 mm, thereby forming a laser resonator having a resonator length of 25 mm together with the selective reflection film 34 described above. is doing.

The pumping semiconductor laser device 33 is a GaAs-based semiconductor laser device having an oscillation wavelength of 800 to 820 nm and an output of 500 mW. This pumping semiconductor laser device 33, when the temperature is kept at 25 ° C.,
The oscillation wavelength is 807 nm which coincides with the absorption peak of the solid-state laser medium 32. The pumping semiconductor laser 33
Are driven by a driving device (not shown).

The condenser lenses 38a and 38b condense the pumping laser light L ₀ emitted from the pumping semiconductor laser device 33 and from the end face of the solid laser medium 32 on which the selective reflection film 34 is formed, to the solid laser. It is excited by being made incident on the medium 32. The degree of focusing is set so that the mode volume of the excitation laser beam L _{0 and} the mode volume of the output laser beam L ₁ can be well matched. The cooling liquid 7 is the same as the cooling liquid 7 used in the first and second embodiments described above.

According to this embodiment, with the cooling liquid 7,
The semiconductor laser device 33 for excitation is set at a precisely constant temperature (25
° C), the wavelength of the excitation laser beam L ₀ can always be accurately maintained at a predetermined wavelength (807 nm), and
The solid-state laser medium 32 can also be maintained at a constant temperature. Moreover, the device can be made extremely small and compact. Therefore, it is possible to obtain a laser beam having excellent beam characteristics that makes full use of the characteristics of edge pumping, and to obtain a semiconductor laser pumped solid-state laser apparatus of edge pumping that can form the apparatus in an extremely small and compact size. When the cooling liquid 7 is held at 25 ° C. and oscillated by using the apparatus of this embodiment, an output laser beam L ₁ having a wavelength of 1064 nm and an output of 150 mW and excellent in both longitudinal and transverse modes can be obtained. You can

Fourth Embodiment FIG. 5 is a longitudinal sectional view of a semiconductor laser pumped solid-state laser device according to a fourth embodiment of the present invention, and FIG. 6 is VI-VI of FIG.
It is a line sectional view. The fourth embodiment will be described below with reference to FIGS. 5 and 6. In this embodiment, a high pressure dry gas as a cooling medium is used as a cooling medium, a side excitation method is adopted as an excitation method, and a total reflection mirror and an output mirror are used in addition to a semiconductor laser device for excitation and a solid-state laser medium. This is an example in which it is stored in a container for cooling.

In FIG. 5, reference numeral 41 is a container and reference numeral 42.
Is a rod-shaped solid-state laser medium, 43 is a pumping semiconductor laser device, 44 is a total reflection mirror, 45 is an output mirror, 46 is a temperature control device, 46a is a thermoelectric element, and 47 is a container 41. It is a high pressure dry gas (cooling medium) enclosed.

The container 41 is made of a material such as aluminum or stainless steel and has a hollow box shape. That is, a hollow portion 41a is formed inside the container 41, and in this hollow portion 41a, a ridge storage portion 41m for storing and fixing the solid-state laser medium 42 and five semiconductor laser devices 43 for excitation.
And a mirror pedestal portion 41p for fixing the total reflection mirror 44. Further, a fixing hole 41b of the output mirror, which is a hole penetrating the hollow portion 41a and the outside and which also serves as a window for taking out the output laser light, is formed at the right end portion of the container 41 in the drawing. Further, the entire inner peripheral surface of the hollow portion 41a is provided with a heat exchange portion 41n processed into a pleated shape to increase the surface area. Then, one surface of a thermoelectric element 46a such as a Peltier element is adhered and fixed to the outer surface portion of the container 41, that is, the bottom surface portion in the figure, and the radiation fin 46 is attached to the other surface of the thermoelectric element 46a.
A radiator 46b provided with c is attached so as to radiate heat. Here, the thermoelectric element 46a is controlled and driven by the temperature control device 46,
By cooling the entire container 41 with the thermoelectric element 46a, the solid-state laser medium 42, the semiconductor laser device 43, and the like inside the container 41 are cooled.

The ridge receiving portion 41m is a solid-state laser medium which is a cylindrical hollow portion in which the inner side surface of the hollow portion 41a is projected toward the center and the solid-state laser medium 42 is housed therein. A housing portion 41i is formed, and a long opening is formed in a part of the solid-state laser medium housing portion 41i along the longitudinal direction, that is, in the lower part of the drawing, and pump laser light is introduced to introduce pump laser light. The window 41q is provided. A rod-shaped solid-state laser medium 42 is stored in the solid-state laser medium storage portion 41i.
It is adapted to be held and fixed in the solid-state laser medium accommodating portion 41i by O-rings or the like attached to both end portions of No. 2. The inner surface of the solid-state laser medium housing portion 41i is a mirror surface or a reflecting surface coated with a reflecting film of aluminum, silver, gold or the like, and the inner peripheral surface of the solid-state laser medium housing portion 41i is The closer to the outer peripheral surface of the solid-state laser medium 42, the closer it is to the contact, and the more efficient heat exchange between them can be performed.

Further, five semiconductor laser devices 43 are arranged at regular intervals along the longitudinal direction of the laser light incident window 41q at a portion of the solid-state laser medium housing portion 41i facing the excited laser light incident window 41q. It These semiconductor laser devices 43 are fixed to a pedestal portion 41f, which is a ridge portion similar to the ridge housing portion 41m, in the lower part of the ridge housing portion 41m in the figure.

Further, the total reflection mirror 44 fixed to the mirror pedestal portion 41p, the solid-state laser medium 42, and the output mirror 45 fixed to the fixing hole 41b of the output mirror are all arranged so that the optical axes thereof are common, and the total reflection mirror 44 is fixed. The reflection mirror 44 and the output mirror 45 form a laser resonator. The output mirror 45 has a fixed hole 41 for the output mirror.
A set screw 41e is screwed into a screw portion formed on the b side, and an O-ring 41d interposed between the set screw 41e and the fixing hole 41b of the output mirror is pressed, whereby the output mirror fixing hole 41b is inserted. In addition to being fixedly held, the airtightness between the hollow portion 41a and the outside is also kept at the same time.

The solid-state laser medium 42 has a wavelength of 1064 nm.
Nd: YAG laser rod for generating a laser beam having a diameter of 3 mmφ and a length of 30 mm. Both end faces are flat-polished to form an antireflection film for the oscillation laser beam. The light absorption peak wavelength of this solid-state laser medium 42 is 807 nm.

The pumping semiconductor laser device 43 has an oscillation wavelength at a predetermined temperature that matches the absorption wavelength peak of 807 nm of the solid-state laser medium 42, and pumps the solid-state laser medium 42 from the side. The semiconductor laser device 43 is driven by a power source (not shown) and
The output per piece is 5W, and the total output of 25 pieces is 25W.

The total reflection mirror 44 has a radius of curvature of 5 m,
It is a concave mirror that totally reflects the light of the oscillation wavelength of the solid-state laser medium 42. Although not shown, the mirror pedestal portion 41p is provided with an adjusting mechanism for changing the angle of the total reflection mirror 44 so that the reflection angle can be adjusted.

The output mirror 45 is a concave mirror having a radius of curvature of 5 m and reflecting 95% of the light of the oscillation wavelength of the solid-state laser medium 42.

A high pressure dry gas 47 of about 3 atm, which is a refrigerant, is enclosed in the container 41. The high-pressure dry gas 47 absorbs the heat generated by the semiconductor laser device 43 and the solid-state laser medium 42, and performs heat exchange by natural convection with the container 41 through the heat exchange section 41n. Thus container 4
The heat absorbed by No. 1 is forcibly absorbed by the thermoelectric element 46a and radiated to the outside by the radiator 46b. As the high-pressure dry gas 47, an inert gas having a small molecular weight such as helium or neon is used. A gas with a small molecular weight absorbs heat, is easy to move, and has an excellent property of transmitting heat. For example, the thermal conductivity of helium is 0.14 W · m ⁻¹ · k ^−1, which is about 6 times that of nitrogen. Since the semiconductor laser device is particularly vulnerable to moisture, it is necessary that the gas as the refrigerant contains as little moisture as possible, and it is desirable to keep the relative humidity at about 20%. The high-pressure dry gas 47 is supplied from a gas intake port (not shown) to the container 4
It is enclosed inside 1. Further, in this embodiment, the method of enclosing the high-pressure dry gas as a refrigerant in the container 41 has been described, but the refrigerant may be circulated and the temperature may be adjusted by an external cooler as in other embodiments. Furthermore, in this embodiment, an example in which a gas is enclosed is given, but it goes without saying that a liquid may be enclosed.

In the above structure, the solid-state laser medium 42 is used.
The semiconductor laser device 43 is indirectly cooled by cooling the container 41. However, since the dry high pressure gas 47 is sealed inside the container 41, the high pressure dry gas 47 is cooled.
Of the solid laser medium 42 and the semiconductor laser device 43 absorb the heat generated by the solid laser medium 42 and the semiconductor laser device 43 and conduct the heat to the heat exchange portion 41n protruding in a pleated shape on the inner surface of the container 41. 43 and 43 are efficiently cooled. Further, the thermal resistance between the solid-state laser medium 42 and the ridge storage portion 41m can be reduced.

The advantages of this embodiment are as follows.

Light loss due to absorption of the refrigerant is small and efficiency is high.

The mirror constituting the laser resonator can also be housed in the same container as the solid-state laser medium and the semiconductor laser device.

When the refrigerant gas is sealed, no external cooler or piping is required, and therefore the handling is easy.

As for the price, gas is cheaper.

Since gas has a lower thermal conductivity than liquid, it is effective in the case of a laser device having a relatively low output with a small number of semiconductor laser devices.

In the above-mentioned embodiment, an example in which the Nd: YAG rod is used as the solid-state laser medium is given. However, as the solid-state laser medium, Nd: YLF and Nd: gla are used.
ss, Er: YAG, Er: YLF, Er: glass
For example, a slab or a polyhedron shape may be used instead of the rod. In that case, it is needless to say that conditions such as a laser resonator should be selected according to each laser medium.

Further, the pumping semiconductor laser device is also made of, for example, InGaP, A or the like depending on the pumping wavelength of the solid-state laser medium.
lGaAs, GaAsP or the like may be used.

[0062]

As described above in detail, in the semiconductor laser pumped solid-state laser device according to the present invention, the pumping semiconductor laser device and the solid-state laser medium are housed in a container, and an insulating transparent liquid or A coolant made of an inert gas is put in, the coolant contacts at least a part of the pumping semiconductor laser device and the solid-state laser medium, and the oscillation wavelength of the pumping semiconductor laser device becomes the absorption wavelength of the solid-state laser medium. It is characterized by cooling to a temperature. This allows
Since the pumping semiconductor laser device and the solid-state laser medium housed inside the container can be directly cooled by a liquid or gas cooling medium, the temperature of the light emitting portion of the semiconductor laser device can be accurately controlled. It is possible to arrange the solid-state laser medium relatively freely. Further, since a large number of pumping semiconductor laser devices can be used, a laser device with higher output can be obtained. Further, since the temperature of the solid-state laser medium can be lowered, stable laser light with good beam quality can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a semiconductor laser pumped solid-state laser device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a semiconductor laser pumped solid-state laser device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a semiconductor laser pumped solid-state laser device according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional view of a semiconductor laser pumped solid-state laser device according to a third embodiment of the present invention.

FIG. 5 is a vertical sectional view of a semiconductor laser pumped solid-state laser device according to a fourth embodiment of the present invention.

6 is a sectional view taken along line VI-VI of FIG.

[Explanation of symbols]

1, 21, 31, 41 ... Vessel, 2, 32, 42 ... Solid-state laser medium, 3, 33, 43 ... Excitation semiconductor laser device,
4, 44 ... Total reflection mirror, 5, 35, 45 ... Output mirror, 6 ... Circulation type temperature control device, 7 ... Coolant, 34 ... Selective reflection film, 38a, 38b ... Condensing lens, 47 ... High pressure dry gas, 46 ... Temperature control device.

Claims (6)

[Claims] 1. A solid-state laser medium disposed in a laser resonator is irradiated with laser light for excitation emitted from an excitation semiconductor laser device, and the solid-state laser medium is excited to obtain output laser light. In the semiconductor laser pumped solid-state laser device described above, the pumping semiconductor laser device and the solid-state laser medium are housed in a container, and an insulating and transparent coolant is put in the container, and the coolant is the pumping semiconductor. At least a part of the laser device and the solid-state laser medium are brought into contact with each other, and the temperature of the coolant is adjusted so that the oscillation wavelength of the excitation semiconductor laser device matches the absorption wavelength of the solid-state laser medium. A semiconductor laser pumped solid-state laser device comprising a temperature control device for maintaining the temperature of the device. 2. The semiconductor laser pumped solid-state laser device according to claim 1, wherein the coolant is a cooling liquid. 3. The semiconductor-laser-pumped solid-state laser device according to claim 1, wherein the coolant is a cooling gas. 4. The semiconductor laser pumped solid-state laser device according to claim 1, wherein the temperature control device takes out a part of the refrigerant from the container and introduces it, and after setting the temperature to a target temperature, A semiconductor laser pumped solid-state laser device characterized by being a circulation type temperature control device which is returned to a container. 5. The semiconductor laser pumped solid-state laser device according to claim 1, wherein the pumping laser light emitted from the pumping semiconductor laser device is applied to the solid-state laser medium from a side surface of the solid-state laser medium. A semiconductor laser pumped solid-state laser device characterized by irradiating a laser medium. 6. The semiconductor laser pumped solid-state laser device according to claim 1, wherein the pumping laser beam emitted from the pumping semiconductor laser device is a resonant laser beam of the solid-state laser medium. A semiconductor laser pumped solid-state laser device characterized in that the solid-state laser medium is irradiated from an end face which is an entrance / exit face.