JP2000077750A - Solid laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a solid laser and to enhance the excitation efficiency of the laser by a method wherein excitation light is made incident in the side surface of a tabular laser medium, and clad members of a small refractive index are provided in contact to the laser medium. SOLUTION: Excitation light outputted from a semiconductor laser 24 is condensed by a group 26 of condensing lenses and the excitation light is incident in the side surface of a laser medium 12. Here, as lower and upper clads 14 and 16 are formed of a YAG crystal, the refractive index of the clads 14 and 16 is 1.82. To this refractive index, as the medium 12 is formed of a Yb: YAG crystal doped with a Yb to the YAG crystal, the refractive index of the medium 12 becomes higher by 0.1 to 0.2% or thereabouts to that of the clads 14 and 16. Accordingly, the light incident in the interface between the medium 12 and the clad 14 or the interface between the medium 12 and the clad 16 at an angle larger than a critical angle is reflected totally on this interface and results in being confined in the medium 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser device.

[0002]

2. Description of the Related Art Solid-state laser devices have been widely used in the fields of material processing, medical treatment, and the like because they can obtain relatively large output laser light from small devices.
In recent years, various researches and developments have been made to further increase the output.

A solid-state laser device usually includes a laser medium that causes laser oscillation, an excitation light source that irradiates the laser medium with excitation light, and a pair of reflectors that form a resonator with the laser medium interposed therebetween. You. The laser medium is generally formed in a rod shape (cylindrical shape) to output a circular beam, and laser light is output in the axial direction of the rod.

However, in a rod-shaped laser medium, the temperature of the center of the rod becomes higher than the temperature of its surface, and this temperature distribution causes a thermal lens effect, which lowers the efficiency of laser light generation. Would.

For this reason, high-power solid-state laser devices include:
For example, "Multiwatt diode-pumped Yb: YAG thin disk las
er continuously tunable between 1018 and 1053 nm ",
OPTICS LETTERS Vol.20, No.7, pp.713-pp.715 (April 1,1
As shown in 995), a structure in which a flat laser medium is mounted on a heat sink is adopted. Here, when the excitation light is made to enter the thin plate-shaped laser medium from the main surface, the optical path length of the excitation light in the laser medium is reduced, and the excitation efficiency is reduced. Therefore, the semiconductor laser 1 described in the above document has a configuration as shown in FIG.
That is, the excitation light emitted from the fiber-coupled semiconductor laser 2 is applied to a flat laser medium 6 placed on a heat sink 5 via a plurality of converging mirrors 3 and reflecting mirrors 4. Irradiation is performed a plurality of times from the surface, and laser light is output via the output mirror 7. With this configuration of the solid-state laser device 1, the excitation light passes through the laser medium 5 eight times in the thickness direction.
As a result, the optical path length of the excitation light passing through the laser medium 6 is increased, and the excitation efficiency can be increased.

[0006]

However, the solid-state laser device 1 has the following problems. That is,
Since the solid-state laser device 1 requires a plurality of converging mirrors 3 and reflecting mirrors 4, the size of the device is increased, and it is extremely difficult to adjust the optical axis of each converging mirror 3 and reflecting mirror 4. become.

When the laser medium 6 is mounted on the heat sink 5, it is necessary to adhere the laser medium 6 to the heat sink 5 via an adhesive such as an In film in consideration of cooling efficiency. However, when such an adhesive substance is used, excitation light is scattered at the interface between the adhesive substance and the laser medium 6, so that the excitation efficiency is reduced.

Here, it is conceivable to provide a dielectric multilayer mirror between the laser medium 6 and the In film. However, the excitation light is applied to the laser medium 6 from various directions by the condenser mirror 3 and the reflection mirror 4. Since the light is incident, it becomes impossible to design a dielectric multilayer mirror having optimal reflection characteristics.

In order to increase the absorption efficiency of the excitation light incident on the laser medium 6, it is conceivable to dope the active ions with rare earth elements (for example, Yb ions) at a high concentration. By YAG
Since laser light absorption occurs and the threshold value of laser oscillation increases, light conversion efficiency from a semiconductor laser to a solid-state laser decreases. When the laser medium 6 is made thick to increase the absorption length in order to avoid the decrease in the light conversion efficiency,
The volume of the laser medium 6 itself increases, and the cooling efficiency decreases.

It is therefore an object of the present invention to solve the above problems and to provide a solid-state laser device which can be miniaturized and has high excitation efficiency.

[0011]

In order to solve the above-mentioned problems, a solid-state laser device according to the present invention is formed in a plate shape by using a plate-shaped laser medium and a material having a refractive index smaller than that of the laser medium. A clad member provided with one main surface in contact with one main surface of the laser medium, a reflective film provided in contact with the other main surface of the clad member, and A heat sink provided on the main surface side, a semi-transparent mirror disposed opposite the reflection film with the laser medium interposed therebetween, a light source for outputting excitation light for exciting the laser medium, and an excitation light output from the light source Converge,
Light condensing means for making the light incident on the side surface of the laser medium.

The light output from the light source is condensed by the condensing means, and the excitation light is made incident on the side surface of the laser medium.
Excitation light that has entered the laser medium passes through the laser medium in a direction parallel to the main surface. As a result, without using optical means such as a condenser lens and a reflection mirror,
The optical path length of the excitation light passing through the laser medium can be lengthened.

Further, by providing a cladding member having a small refractive index in contact with the laser medium, most of the excitation light incident from the side surface of the laser medium is totally reflected at the interface between the laser medium and the cladding member, and the excitation light is emitted by the laser. Trapped in the medium. Further, since no adhesive substance is provided at the interface between the laser medium and the clad member, scattering of the excitation light at the interface is prevented.

The solid-state laser device of the present invention is formed in a plate shape by using a material having a refractive index substantially equal to that of the clad member, and has a second main surface provided in contact with the other main surface of the laser medium. It may be characterized by further comprising a clad member.

By providing a second clad member having the same refractive index as the clad member in contact with the other main surface of the laser medium, the critical angle on one main surface of the laser medium and the critical angle on the other peripheral surface can be reduced. Can be substantially matched.

In the solid-state laser device according to the present invention, the condensing means includes:
First light flux conversion means for condensing light output from the light source in the thickness direction of the side surface of the laser medium; and condensing or diffusing light output from the light source in the width direction of the side surface of the laser medium. A second light flux conversion means may be provided.

First light beam converting means for condensing light output from the light source in the thickness direction of the side surface of the laser medium, and second light beam converting means for condensing or diffusing light in the width direction of the side surface of the laser medium. With this configuration, a light beam having a linear, elliptical, or rectangular beam spot spreading only in the width direction of the side surface of the laser medium can be incident on the side surface of the laser medium.

The solid-state laser device according to the present invention may be characterized in that the reflection film is a dielectric multilayer film.

By making the reflective film a dielectric multilayer film,
It is possible to increase the reflectance of the reflection film of the stimulated emission light stimulated in the laser medium.

In the solid-state laser device according to the present invention, the cladding member is formed of YAG crystal, and the laser medium is YAG crystal.
It may be characterized by being formed from a Yb: YAG crystal in which Yb is doped into the crystal.

The clad member is formed of YAG crystal, and the laser medium is Yb: YAG in which Yb is doped into YAG crystal.
By forming from a crystal, a laser medium and a clad member having a lower refractive index than the laser medium can be formed relatively easily.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid-state laser device according to an embodiment of the present invention will be described with reference to the drawings. First, the configuration of the solid-state laser device according to the present embodiment will be described.
FIG. 1 is a configuration diagram of the solid-state laser device according to the present embodiment.

The solid-state laser device 10 includes a flat laser medium 12, a lower clad 14 (cladding member) and an upper cladding 16 (second cladding member) provided so as to sandwich the laser medium 12. A dielectric multilayer film 18 provided below the lower cladding 14;
A heat sink 20 provided below the lower cladding 14 via a laser medium 12 and a dielectric multilayer film 18 with the laser medium 12 interposed therebetween.
An output mirror 22 (translucent mirror) arranged opposite to
A semiconductor laser 24 (light source) that outputs excitation light that excites the laser medium 12 and a condenser lens group 26 that condenses the excitation light output from the semiconductor laser 24 and makes the excitation light incident on the side surface of the laser medium 12 Is done. Hereinafter, each component will be described in detail.

The laser medium 12 is made of a Yb: YAG crystal obtained by doping Yb into a YAG crystal, and has a main surface of about 5 mm square and a flat plate having a thickness of about 0.3 mm. ing.

Lower cladding 14 and upper cladding 16
Is formed from a YAG crystal and has a shape of about 5 m.
It has an m-square main surface and is a flat plate having a thickness of about 0.2 mm.

The lower surface (one main surface) of the laser medium 12 and the upper surface (one main surface) of the lower cladding 14, and the upper surface (the other main surface) of the laser medium 12 and the lower surface (one main surface) of the upper cladding 16. The main surfaces are joined to each other by a method of applying pressure at a high temperature (diffusion bonding method).

On the lower surface (the other main surface) of the lower cladding 14, a dielectric multilayer film 18 is formed over the entire lower surface. The dielectric multilayer film 18 is configured by alternately laminating 10 SiO ₂ layers having a refractive index of 1.46 and TiO ₂ layers having a refractive index of 2.3 from the lower surface side of the lower clad 14 alternately. Each layer has a thickness such that the product of the layer thickness and the refractive index of the material is one quarter of the wavelength of the stimulated emission light (1030 nm) in order to increase the reflectance of the stimulated emission light serving as output light. are doing. On the upper surface of the upper clad 16, in order to prevent the reflection of stimulated emission light generated in the laser medium 12. Particularly, the antireflection film 19 made of MgF ₂ is formed.

A copper heat sink 20 is provided below the lower clad 14 so as to cover the lower clad 14 with a dielectric multilayer film 18 interposed therebetween. Here, the lower surface of the lower clad 14 provided with the dielectric multilayer film 18 and the heat sink 20 are in close contact with each other via an In film 28 having a thickness of about 50 μm.

The position facing the dielectric multilayer film 18 with the laser medium 12 interposed therebetween, more specifically, the upper clad 1
An output mirror 22 that transmits a part of the incident light and reflects a part of the incident light is provided at a position on the upper surface side of the device 6 and facing the dielectric multilayer film 18. A laser resonator is constituted by the dielectric multilayer film 18.

The semiconductor laser 24 moves a semiconductor laser bar 30 that emits a laser beam (wavelength 940 nm) having a linear beam spot of about 1 cm length through a CuW spacer 32 in the linear direction (see FIG. 1). Six layers are stacked in the direction perpendicular to the paper surface (hereinafter referred to as the z-axis direction) and the direction perpendicular to the paper (y-axis direction), and sandwiched by a copper heat sink 33. Here, since the thickness of the spacer 32 is about 0.4 mm, the lamination pitch of the semiconductor laser bars 30 is also about 0.4 mm. Excitation light output from the semiconductor laser 24, that is, excitation light emitted from each semiconductor laser bar 30, travels in the x-axis direction while spreading in the z-axis direction and the y-axis direction.

In front of the semiconductor laser 24, that is, at a position facing the emission surface of the semiconductor laser 24, the pumping light output from the semiconductor laser 24 is condensed and the laser medium 1 is focused.
A condensing lens group 26 for making the light enter the second side surface is provided. The condenser lens group 26 includes a microlens array 34, a first cylindrical lens 3 from the semiconductor laser 24 side.
6. The configuration is such that a second cylindrical lens 38 (first light beam conversion means) and a third cylindrical lens 40 (second light beam conversion means) are sequentially arranged. Also,
FIG. 2 is a schematic plan view when the condenser lens group 26 is viewed from the y-axis direction in FIG.

The microlens array 34 is formed of a columnar lens having a diameter of about 0.4 mm, which is arranged near the emission surface of each semiconductor laser bar 30 so that its axis is parallel to the z-axis. Here, since the semiconductor laser 24 has a configuration in which six semiconductor laser bars 30 are stacked, the microlens array 34 also has a configuration in which the six cylindrical lenses are arranged. The excitation light emitted from each semiconductor laser bar 30 and having a divergence angle of about 40 ° with respect to the y-axis direction by the microlens array 34 is condensed in the y-axis direction and spread in the y-axis direction. It becomes parallel light that travels without moving.

The first cylindrical lens 36 is a cylindrical lens whose one main surface is a plane surface and the other main surface is a convex cylindrical surface, and is arranged such that the bottom surface of the cylinder is parallel to the xz plane. I have. Emitted from the semiconductor laser 24 by the first cylindrical lens 36, z
Excitation light having a divergence angle of about 10 ° with respect to the axial direction is:
The light is condensed in the z-axis direction and becomes parallel light that travels without spreading in the z-axis direction.

The second cylindrical lens 38 is a cylindrical lens having one main surface being a flat surface and the other main surface being a convex cylindrical surface, and is arranged such that the bottom surface of the cylinder is parallel to the xy plane. I have. The excitation light emitted from the semiconductor laser 24 by the second cylindrical lens 38 and collimated by the microlens array 34 and the first cylindrical lens 36 is directed in the thickness direction of the side surface of the laser medium 12, that is, in the y-axis direction. It is collected.

The third cylindrical lens 40 is a cylindrical lens having one main surface being a flat surface and the other main surface being a convex cylindrical surface, and is arranged such that the bottom surface of the cylinder is parallel to the xz plane. I have. The excitation light emitted from the semiconductor laser 24 by the third cylindrical lens 40 and collimated by the microlens array 34 and the first cylindrical lens 36 is collected in the width direction of the side surface of the laser medium 12, that is, in the z-axis direction. Be lighted.

Accordingly, the excitation light output from the semiconductor laser 24 is independently focused by the condenser lens group 26 in each of the y-axis direction and the z-axis direction. as a result,
Excitation light having a substantially linear, elliptical or rectangular beam spot extending in the z-axis direction can be formed, and such excitation light is incident on one of the side surfaces of the laser medium 12. Here, the first lens constituting the condenser lens group 26
The positions or focal lengths of the cylindrical lens 36, the second cylindrical lens 38, and the third cylindrical lens 40 are appropriately adjusted so that the excitation light output from the semiconductor laser 24 is efficiently incident on the side surface of the laser medium 12. Preferably, the laser medium 1
Preferably, the numerical aperture (NA) for 2 is 0.1 or less. Further, the micro lens array 3
4. First cylindrical lens 36, second cylindrical lens 38, and third cylindrical lens 40
Is coated with an antireflection film made of a dielectric multilayer film in order to prevent surface reflection of the excitation light.

An anti-reflection film 42 made of MgF ₂ is provided on one of the side surfaces of the laser medium 12 on which the excitation light is incident (hereinafter referred to as an incident surface) in order to prevent reflection of the incident excitation light. A reflection film 44 made of SiO ₂ and TiO ₂ is provided on a side surface other than the incident surface to confine the incident excitation light in the laser medium 12.

Next, the operation of the solid-state laser device according to this embodiment will be described. When using the solid-state laser device 10 according to the present embodiment, first, the semiconductor laser 24 generates excitation light. Excitation light output from the semiconductor laser 24 is condensed by the condenser lens group 26 and is incident on the side surface of the laser medium 12. Here, the condenser lens group 26 includes a second cylindrical lens 38 for condensing the excitation light in the y-axis direction and a third cylindrical lens 38 for condensing the excitation light in the z-axis direction.
By providing the cylindrical lens 40, the cross section of the excitation light beam can be made substantially linear (or rectangular or elliptical), and the excitation light can be efficiently incident on the incident surface of the laser medium 12. Become.

When excitation light is incident on the laser medium 12 and the excitation light is absorbed by Yb ions doped into the laser medium 12, the energy state of the Yb ions transitions, and stimulated emission light is generated. Here, the excitation light incident on the incident surface of the laser medium 12 behaves as shown in FIG.

The anti-reflection film 4 is provided on the incident surface of the laser medium 12.
2, the excitation light enters the laser medium 12 without reflection loss at the incident surface. Here, since the lower cladding 14 and the upper cladding 16 are formed of a YAG crystal, the refractive index thereof is 1.82. On the other hand, the laser medium 12 has a YAG crystal
Since the lower cladding 14 and the upper cladding 16 are formed from a Yb: YAG crystal doped with b,
The refractive index is higher by about 0.1 to 0.2%. Therefore, light that enters the interface between the laser medium 12 and the lower cladding 14 or the interface between the laser medium 12 and the upper cladding 16 at an angle larger than the critical angle is totally reflected at the interface and enters the laser medium 12. You will be confined. The pumping light incident from the side surface of the laser medium 12 travels in the laser medium 12 in a direction almost parallel to the main surface, so that the interface between the laser medium 12 and the lower cladding 14 or the laser medium 12 and the upper cladding 16 The angle of incidence on the interface with is large, and most of the excitation light is totally reflected at the interface. here,
In particular, when the condenser lens group 26 is designed such that the numerical aperture (NA) with respect to the laser medium 12 is 0.1 or less, almost 100% of the excitation light incident on the laser medium 12
Satisfy the total reflection condition, and the pump light is efficiently confined in the laser medium 12. Laser medium 1
2 is provided with the reflective film 44 on the side surface other than the incident surface, so that the excitation light reaching the surface facing the incident surface
4 and travels in the direction of the incident surface again. As a result, it becomes possible to make the optical path length of the excitation light traveling in the laser medium 12 extremely large. Further, no layer such as an In film is provided at the interface between the laser medium 12 and the lower cladding 14 or at the interface between the laser medium 12 and the upper cladding 16, and the excitation light is confined in the laser medium 12 by a change in the refractive index. Thereby, scattering of the excitation light at such an interface is prevented. In this configuration, the lower cladding 14 and the upper cladding 16 are formed of a YAG crystal, and the laser medium 12 is formed of a Yb: YAG crystal obtained by doping Yb into a YAG crystal, so that a special manufacturing process or the like is not required. Yes, and can be formed relatively easily.

Wavelength 1030n generated by stimulated emission
The light of m is amplified by a resonance effect via the dielectric multilayer film 18 and the output mirror 22, and is emitted as laser light in the direction of the normal to the main surface of the laser medium 12, that is, in the y-axis direction in FIG. At this time, by providing the dielectric multilayer film 18 as a reflecting mirror constituting the resonator, only the light having the wavelength of 1030 nm can be efficiently reflected, and the antireflection film 19 is formed on the upper surface of the upper cladding 16. This prevents the laser light from being reflected on the upper surface of the upper cladding 16.

While the laser oscillation is occurring, the laser medium 1
2 is cooled by the heat sink 20. Here, since the laser medium 12 has a flat plate shape, the entire laser medium 12 is extremely efficiently cooled as compared with a rod-shaped laser medium. Here, a slight temperature gradient may occur in the laser medium 12 depending on the thickness of the laser medium 12, the cooling ability of the heat sink 20, and the like. 1 is a one-dimensional temperature gradient in the y-axis direction, and has no effect on the laser light emitted in the y-axis direction due to the thermal lens effect, the thermal deformation of the laser medium 12, and the like.

Next, the effect of the solid-state laser device according to this embodiment will be described. In the solid-state laser device 10 according to the present embodiment, the excitation light emitted from the semiconductor laser 24 is focused in the y-axis direction by the second cylindrical lens 38, and is focused in the z-axis direction by the third cylindrical lens 40. . Therefore, the beam spot of the excitation light can be made substantially linear, elliptical or rectangular, and the excitation light can be uniformly and efficiently incident on the incident surface, which is one side surface of the laser medium 12. As a result, the excitation efficiency of the solid-state laser device 10 is improved.

The solid-state laser device 10 according to the present embodiment has a structure in which reflected light is incident from the side and the laser medium 12 is sandwiched between a lower clad 14 and an upper clad 16 having a lower refractive index than the laser medium 12. And the numerical aperture (NA) for the laser medium 12 is 0.2.
The condenser lens group 26 is designed to be 1 or less.
Therefore, the excitation light is emitted from the laser medium 12 and the lower cladding 14.
Or the laser medium 12 and the upper cladding 16
Almost 100% of the light is totally reflected at the interface with the light. In addition, since the reflection film 44 is provided on a side surface other than the incident surface of the laser medium 12, the excitation light reaching the surface facing the incident surface is reflected by the reflective film 44, and travels in the direction of the incident surface again. . As a result, the optical path length of the excitation light traveling in the laser medium 12 can be made extremely large, and the excitation efficiency is improved. Furthermore, since the optical path length of the excitation light traveling in the laser medium 12 can be made extremely large without providing special optical means such as a condenser mirror and a reflection mirror, the size of the apparatus can be reduced.

Further, in the solid-state laser device 10 according to the present embodiment, since the laser medium 12 and the lower clad 14 and the upper clad 16 do not use an adhesive substance or the like when they are brought into close contact with each other, the excitation light is scattered at the interface. Is prevented. As a result, light loss due to scattering is suppressed, and the excitation efficiency is improved.

The solid-state laser device 1 according to the present embodiment
0 denotes a dielectric multilayer film 18 as a reflecting mirror constituting a resonator.
Is used, only the stimulated emission light is efficiently reflected, and the laser emission efficiency can be improved.

The efficiency of the solid-state laser device 10 according to the present embodiment and the efficiency of the solid-state laser device 1 according to the prior art are compared as follows. The solid-state laser device 1 according to the prior art has an optical coupling efficiency of about 80% when guiding the pump light emitted from the semiconductor laser to the optical fiber, and collects the pump light output from the output end of the optical fiber. Since the incidence efficiency at the time of entering the laser medium 6 through the mirror 3 and the reflection mirror 4 is about 70%, and the absorption efficiency of the excitation light in the laser medium 6 is about 90%, these efficiencies are multiplied. As a result, the excitation efficiency becomes about 50%.

On the other hand, the solid-state laser device 10 according to the present embodiment has an incident efficiency of about 95 when the excitation light output from the semiconductor laser 24 is incident on the laser medium 12 via the condenser lens group 26. %, And the absorption efficiency of the pumping light in the laser medium 12 is about 99%. By multiplying these efficiencies, the pumping efficiency becomes about 94%, which is smaller than that of the solid-state laser device 1 according to the related art. As a result, the excitation efficiency becomes extremely high.

In the solid-state laser device 10 according to the above embodiment, the laser medium 12 is sandwiched between the lower clad 14 and the upper clad 16, but the upper clad 16 is provided as shown in FIG. No solid-state laser device 5
A configuration like 0 may be used. Even when the upper cladding 16 is not provided, since the refractive index of the laser medium 12 is larger than the refractive index (1.00) of air, the laser medium 12 and the air have an incident angle greater than the critical angle. Excitation light incident on the interface is totally reflected at the interface, and the laser medium 1
2 confined within.

Further, in the solid-state laser device 10 according to the above embodiment, the third cylindrical lens 40
Although the lens has a convex main surface, it may have a concave main surface and diffuse excitation light output from the semiconductor laser 24 in the width direction of the side surface of the laser medium 12. good. If the spread of the excitation light emitted from the semiconductor laser bar 30 in the z-axis direction is smaller than the width of the side surface of the laser medium 12, the beam spot is formed by using the cylindrical lens having the concave main surface. The excitation light can be uniformly and efficiently incident on the side surface of the laser medium 12 by diffusing in the width direction of the laser medium 12.

Further, in the solid-state laser device 10 according to the above-described embodiment, YA is used as the mother crystal of the laser medium 12.
A G crystal was used, but this was done using YLF, YVO ₄ , S-
It can also be realized by using various materials usually used as a laser medium of a solid-state laser device, such as FAP, sapphire, glass, alexandrite, forsterite, and garnet. In particular, when a single crystal sapphire or the like having a smaller refractive index and higher thermal conductivity than the YAG crystal is used as the cladding material, the pumping efficiency becomes extremely high, and a high-output solid-state laser device is realized.

The element to be doped is not limited to Yb, and other rare earth elements such as Nd, Er, Ho, and Tm, and transition elements such as Cr and Ti can be used.

[0053]

According to the solid-state laser device of the present invention, the pumping light is incident on the side surface of the flat laser medium, and a cladding member having a small refractive index is provided in contact with the laser medium, so that the pumping light enters the laser medium. It is possible to confine and lengthen the optical path length of the excitation light passing through the laser medium. As a result, a solid-state laser device with high excitation efficiency is realized. In addition, it is not necessary to provide a special optical unit such as a reflection mirror for increasing the optical path length of the excitation light, and the solid-state laser device can be made compact.

Further, in the solid-state laser device of the present invention, by providing a second clad member having the same refractive index as the clad member in contact with the other main surface of the laser medium, It is possible to make the angle substantially coincide with the critical angle on the other peripheral surface. As a result, the excitation light can be transmitted uniformly through the laser medium, and the excitation efficiency is improved.

Further, in the solid-state laser device according to the present invention, the excitation light output from the light source is condensed in the thickness direction on the side surface of the laser medium by the first light beam conversion means, and the laser light is emitted by the second light beam conversion means. By condensing or diffusing the light in the width direction of the side surface of the medium, a light beam having a substantially linear, elliptical or rectangular beam spot having a spread only in the width direction of the side surface of the laser medium is formed. The light can be uniformly and efficiently incident on the side surface, and the excitation efficiency is improved.

Further, in the solid-state laser device of the present invention, by using a dielectric multilayer film as the reflection film, it is possible to selectively increase the reflectance of light emitted in the laser medium, and to improve the laser generation efficiency. Is improved.

Further, in the solid-state laser device of the present invention, the cladding member is made of YAG crystal, and the laser medium is made of YAG crystal with Yb crystal.
, A solid-state laser device can be formed relatively easily.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a solid-state laser device.

FIG. 2 is a schematic plan view of a condenser lens group.

FIG. 3 is an explanatory diagram showing a light path in a laser medium.

FIG. 4 is a configuration diagram of a solid-state laser device.

FIG. 5 is a configuration diagram of a conventional solid-state laser device.

[Explanation of symbols]

10, 50: solid-state laser device, 12: laser medium, 14
... lower cladding, 16 ... upper cladding, 18 ... dielectric multilayer film, 19 ... antireflection film, 20 ... heat sink, 22 ...
Output mirror, 24 semiconductor laser, 26 condensing lens group, 28 In film, 30 semiconductor laser bar, 32 spacer, 33 heat sink, 34 microlens array, 36 first cylindrical lens, 38 second 2
, A third cylindrical lens, 42, an antireflection film, 44, a reflection film

Claims (5)

[Claims] 1. A flat plate-shaped laser medium and a material having a lower refractive index than the laser medium are formed in a flat plate shape, and one main surface thereof is provided in contact with one main surface of the laser medium. A cladding member, a reflection film provided in contact with the other main surface of the cladding member, a heat sink provided on the other main surface side of the cladding member via the reflection film, and the laser medium. A translucent mirror disposed so as to face the reflection film, a light source that outputs excitation light that excites the laser medium, and a side surface of the laser medium that collects the excitation light output from the light source. A solid-state laser device comprising: a light condensing means for causing light to enter the laser beam. 2. A second clad member, which is formed of a material having a refractive index substantially equal to that of the clad member in a plate shape and has one main surface provided in contact with the other main surface of the laser medium, 2. The device according to claim 1, wherein
3. The solid-state laser device according to item 1. 3. The light condensing means, a first light beam converting means for condensing light output from the light source in a thickness direction of a side surface of the laser medium, and a light output from the light source, 3. The solid-state laser device according to claim 1, further comprising: a second light beam converting unit that collects or diffuses light in a width direction of a side surface of the laser medium. 4. 4. The solid-state laser device according to claim 1, wherein said reflection film is a dielectric multilayer film. 5. The laser medium according to claim 1, wherein the cladding member is formed of a YAG crystal, and the laser medium is a YAG crystal doped with Yb.
The solid-state laser device according to any one of claims 1 to 4, wherein the solid-state laser device is formed of b: YAG crystal.