JPH1117254A - Solid-state laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs, to simplify assembly and adjustment, to attain the high output and high efficiency of a TEM mode, to obtain the satisfactory introduction efficiency of an excitation light to a solid laser medium, and to prevent the generation of the unavailability of the device. SOLUTION: A device is provided with a laser resonator 3 having a total reflecting mirror 7 and an output mirror 8, a truncated conical condenser 4 arranged in the laser resonator 3 for converging an excitation light O from an LD2, and cylindrical fine diameter solid laser medium 5 connected with a small edge face 4b among both edge faces 4a and 4b of the condenser 4 which is excited by the excitation light O. Also, dielectric multilayered films 9 and 10 are formed on each side face of the solid laser medium 5 and the condenser 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid-state laser device using a laser diode (hereinafter abbreviated as "LD") as an excitation light source.

[0002]

2. Description of the Related Art Generally, a solid-state laser device of this kind includes:
A single-chip type LD with an output of about 1 to 4 W (continuous oscillation high output), and a bar type L with an output of about 10 to 20 W in which a large number of single-chip LDs are arranged one-dimensionally with a width of about 10 mm.
There is known a device provided with a semiconductor laser such as a two-dimensional stacked LD in which D or LD bars are vertically stacked.

In such a solid-state laser apparatus, a side-pumping method in which the arrangement of pumping light sources is relatively free is considered to be advantageous for increasing the output.

In this type of solid-state laser device, in order to increase the output in the TEM00 mode (TEM mode), the number of LDs used as the pumping light source is increased to increase the pumping light input, and the solid-state laser medium is used. It is necessary to efficiently absorb the excitation light within the volume of the laser beam.

Further, when a large number of semiconductor lasers are used in a solid-state laser device, the pumping light input increases, but at the same time, the emission area increases, so that the pumping density in the TEM mode volume of the solid-state laser medium decreases. Since the oscillation efficiency in the TEM mode is reduced, it is necessary to devise a condensing optical system for the excitation light.

Conventionally, a solid-state laser device of this type has been disclosed in Japanese Patent Application Laid-Open No. 4-25085. In this method, a resonator having a mirror coating process is provided on both end faces of a solid-state laser medium, and LD oscillation light is incident from the end face of the solid-state laser medium and excited using a coupling optical system.

A conventional solid-state laser device disclosed in Japanese Patent Application Laid-Open No. 1-251678 is also employed. That is, by using a plurality of LDs, the pumping light of each of these LDs is introduced into an optical fiber, and the cores at the fiber output ends are fused together to synthesize the pumping light,
Excitation is performed from the end face of the solid-state laser medium via the coupling optical system.

[0008]

However, in the conventional solid-state laser device, since the coupling optical system is used, the number of parts is increased, the cost is increased, and the assembly adjustment is complicated. was there.

In the former case, since the excitation light is focused on a small area on the end face of the solid-state laser medium, the distortion due to the generation of heat and the thermal lens effect increase. There is also a problem that the beam quality of the (excitation light) is reduced, and in the worst case, the solid-state laser medium is broken.

Furthermore, since it is difficult to use a large number of LDs, there has been a problem that it is not possible to realize high output and high efficiency in the TEM mode.

On the other hand, in the latter case, LD light (excitation light)
However, since an optical fiber is used for transmitting the laser beam, there is a disadvantage that it is not possible to obtain a good efficiency of introducing the LD light into the optical fiber (solid laser medium).

In addition, since the introduction of the excitation light into the light collector is performed by fusing the cores of a plurality of optical fibers together, there is also an inconvenience that the end face of the fiber is damaged and the device becomes unusable. .

The present invention has been made in view of such circumstances, and has been made to reduce costs, simplify assembly and adjustment, and improve the TE.
A solid-state laser device that can achieve high output and high efficiency of the M mode, can obtain good introduction efficiency of pumping light into the solid-state laser medium, and can prevent the device from becoming unusable. For the purpose of providing.

[0014]

According to a first aspect of the present invention, there is provided a solid-state laser device comprising: a laser resonator having a total reflection mirror and an output mirror; and a laser resonator provided in the laser resonator. A concentrator made of a truncated cone for condensing the excitation light from the excitation light source, and a small diameter consisting of a cylindrical body joined to the small end face of both end faces of the condenser and excited by the excitation light , And each side surface of the solid-state laser medium and the condenser is formed by a peripheral surface having a high reflectance with respect to the excitation light from the excitation light source. Therefore, the excitation light from the excitation light source enters from the large end face of the light collector, is reflected from the side face, exits from the small end face, and is condensed on the end face of the solid-state laser medium to excite the solid-state laser medium.

According to a second aspect of the present invention, in the solid-state laser device according to the first aspect, the excitation light source includes a plurality of laser diodes. Therefore, the pump light output increases as the number of pump light sources increases.

The third aspect of the present invention is the first or second aspect.
In the above-described solid-state laser device, a heat-dissipating block is provided around the solid-state laser medium and the condenser. Therefore, the heat generated from the excitation light incident end face of the solid-state laser medium is transmitted not only to the solid-state laser medium but also to the heat-dissipating block via the condenser, and is dissipated from this heat-dissipating block.

According to a fourth aspect of the present invention, in the solid-state laser device according to any one of the first to third aspects, the diameter of the solid-state laser medium is set to be twice as large as the TEM mode diameter in the laser resonator. There is a configuration. Therefore, the solid-state laser medium functions as a mode selector, and TEM mode laser light selectively oscillates.

According to a fifth aspect of the present invention, in the solid-state laser device according to any one of the first to fourth aspects, a metal layer treatment is applied to each peripheral surface of the solid-state laser medium and the condenser. is there. Therefore, the excitation light propagates while being reflected by the solid-state laser medium and the metal layer of the condenser, and the solid-state laser medium is uniformly excited.

According to a sixth aspect of the present invention, in the solid-state laser device according to any one of the first to fourth aspects, a dielectric multilayer film treatment is applied to each peripheral surface of the solid-state laser medium and the condenser. There is a configuration. Therefore, the excitation light propagates while being reflected by the solid-state laser medium and the dielectric multilayer film of the condenser, and the solid-state laser medium is uniformly excited.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 is an optical path diagram showing the solid-state laser device according to the first embodiment of the present invention. In the figure, a solid-state laser device denoted by reference numeral 1 includes an LD 2, a laser resonator 3, a condenser 4, a solid-state laser medium 5,
And

The LD 2 is an LD that oscillates in the vicinity of a wavelength band of 809 nm in the solid-state laser medium 5 where absorption is good, and emits pump light O to the laser resonator 3 to excite the solid-state laser medium 5. Thereby, the solid-state laser medium 5
Within it, a population inversion of energy is formed.

The laser resonator 3 is a laser resonator having a TEM mode diameter of about 0.5 mm in the solid-state laser medium 5, and has a total reflection mirror 7 and an output mirror 8. Accordingly, the laser oscillation light L having a wavelength of 1.064 μm oscillates in the TEM mode.

The light collector 4 has a thermal expansion coefficient similar to that of the solid-state laser medium 5, a thermal conductivity equal to or higher than that of the solid-state laser medium 5, and a truncated cone-shaped light collector having a high transmittance to the excitation light O. And is provided in the laser resonator 3. A dielectric multilayer film 9 is formed on the peripheral surface (side surface) of the light collector 4 by vapor deposition. As a result, the excitation light O from the LD 2 is collected while being reflected by the dielectric multilayer film 9, and the solid-state laser medium 5 is collected.
Incident on.

The solid-state laser medium 5 is a cylindrical (rod) -shaped solid-state laser medium (Nd:
YAG) and is joined to the small end face 4b of both end faces 4a and 4b of the light collector 4 by optical contact or fusion. Peripheral surface (side surface) of solid-state laser medium 5
In the same way as the light collector 4, the dielectric multilayer film 10 is formed by vapor deposition.
Are formed. As a result, the excitation light O propagates while being reflected by the dielectric multilayer film 10 and is absorbed.

The diameter of the solid-state laser medium 5 is set to a dimension (1 mm) that is about twice the TEM mode diameter in the laser resonator 3. Thus, the solid-state laser medium 5 functions as a mode selector, and the TEM mode selectively oscillates. The length of the solid-state laser medium 5 is set to a dimension of 5 mm.

The heat radiating block 6 is composed of a heat radiating block made of a heat conductive member such as copper, and is disposed around the concentrator 4 and the solid-state laser medium 5. As a result, heat generated near the end face (excitation light incident end face) of the solid-state laser medium 5 is conducted and radiated from the condenser 4 and the solid-state laser medium 5.

In the solid-state laser device thus configured, the excitation light O from the LD 2 is applied to both end faces 4 of the condenser 4.
The incident light from the large end face 4a and the light emitted from the small end face 4b while being reflected on the side face are focused on the end face of the solid laser medium 5 to excite the solid laser medium 5. Therefore, in the present embodiment, the coupling optical system conventionally required for the light collector becomes unnecessary, and the number of components can be reduced.

Further, in this embodiment, the fact that the end face of the condenser 4 is joined to the end face of the excitation light of the solid-state laser medium 5 means that the heat generated at the end face of the excitation light is also radiated to the condenser 4. At the same time, since the excitation light O is uniformly focused on the end face of the solid-state laser medium 5, heat concentration at one location is reduced, and thermal distortion and thermal lens effect are suppressed.

Further, in this embodiment, oscillation modes other than the TEM mode are suppressed by the small-diameter solid-state laser medium 5, and the excitation light O is absorbed by the dielectric multilayer film 9 while being reflected in the solid-state laser medium 5. You.

In the present embodiment, the case where the LD 2 is singular has been described, but the present invention is not limited to this, and as shown in FIG. 2 (second embodiment), a plurality (for example, three) LD11 can be used. in this case,
The pump light output increases in proportion to the increase in the number of LDs 11, and T
The output can be increased in the EM mode. In the figure,
Reference numeral 12 denotes a heat radiation block.

Further, in the present embodiment, the dielectric multilayer films 9 and 10 are provided on the respective side surfaces of the solid-state laser medium 5 and the condenser 4.
Although the example which forms is shown, the present invention is not limited to this,
Even if a metal layer is formed by vapor deposition or plating, the same effect as in the embodiment can be obtained.

[0032]

As described above, according to the present invention, a laser resonator having a total reflection mirror and an output mirror,
A concentrator, which is provided in the laser cavity and is formed of a truncated cone for condensing the excitation light from the excitation light source, is joined to a small end face of both end faces of the concentrator, and is excited by the excitation light. A solid-state laser medium having a small diameter formed of a cylindrical body, and each side surface of the solid-state laser medium and the concentrator is formed by a peripheral surface having a high reflectance with respect to excitation light from an excitation light source.
Excitation light from an excitation light source is incident from the large end face of both end faces of the light collector, is emitted from the small end face while being reflected on the side face, and is condensed on the end face of the solid laser medium to excite the solid laser medium.

Therefore, the coupling optical system conventionally required for the light collector becomes unnecessary, so that the number of parts can be reduced, the cost can be reduced, and the assembly adjustment can be simplified.

In addition, the fact that the condenser is joined to the excitation light incident end face of the solid-state laser medium means that the heat generated at the excitation light incidence end face is radiated to the condenser and the excitation light is also transmitted to the end face of the solid-state laser medium. Since light is condensed uniformly, heat concentration at one location is reduced, thermal distortion and thermal lens effect can be suppressed, and beam quality can be improved.

In addition, the small-diameter solid-state laser medium makes T
Oscillation modes other than the EM mode are suppressed, and the excitation light is absorbed by the high-reflectivity surface while being reflected in the solid-state laser medium. Therefore, high output and high efficiency in the TEM mode can be achieved.

In addition, since the pumping light can be introduced into the solid-state laser medium by the conical concentrator, good pumping light introduction efficiency to the solid-state laser medium can be obtained.

Further, since the introduction of the excitation light into the light collector is not performed by fusing the optical fibers together as in the conventional case, it is possible to prevent the apparatus from becoming unusable due to damage to the components.

[Brief description of the drawings]

FIG. 1 is an optical path diagram showing a solid-state laser device according to a first embodiment of the present invention.

FIG. 2 is an optical path diagram showing a solid-state laser device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid-state laser apparatus 2 LD 3 Laser resonator 4 Condenser 5 Solid-state laser medium 6 Heat dissipation block 7 Total reflection mirror 8 Output mirror 9,10 Dielectric multilayer film L Laser oscillation light O Excitation light

Claims (6)

[Claims] 1. A laser resonator having a total reflection mirror and an output mirror, a concentrator disposed in the laser resonator and formed of a truncated cone for condensing excitation light from an excitation light source; A small-diameter solid-state laser medium which is joined to a small end face of both end faces of the optical device and is formed of a cylindrical body which is excited by the excitation light. A solid-state laser device formed on a peripheral surface having a high reflectance with respect to the excitation light from the light source. 2. The solid-state laser device according to claim 1, wherein said excitation light source comprises a plurality of laser diodes. 3. The solid-state laser device according to claim 1, wherein a heat dissipation block is provided around the solid-state laser medium and the light collector. 4. The solid-state laser device according to claim 1, wherein the diameter of the solid-state laser medium is set to twice the TEM mode diameter in the laser resonator. 5. The solid-state laser device according to claim 1, wherein a metal layer treatment is applied to each peripheral surface of said solid-state laser medium and said concentrator. 6. The solid-state laser device according to claim 1, wherein a dielectric multilayer film treatment is applied to each peripheral surface of said solid-state laser medium and said concentrator.