JP2004179319A - Solid-state laser oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state laser oscillator suitable for miniaturization, capable of efficiently outputting a laser beam of a prescribed intensity even with a small number of semiconductor laser devices. <P>SOLUTION: The solid-state laser oscillator 1 has a first and a second semiconductor laser devices 2 and 3 facing each other and a first and a second laser mediums 4 and 5 arranged in between the two. On the laser device sides of the laser mediums 4 and 5, a first and a second laser reflecting surfaces 4A and 5A are formed by reflecting a laser beam L and letting through exciting lights LD, with the laser reflecting surfaces 4A and 5A having convex shapes protruding in the facing direction with each other. The laser beam L oscillated by the exciting lights LD from the semiconductor laser devices 2 and 3 is alternately reflected by the first and the second laser reflecting surfaces 4A and 5A before landing on a front and a rear mirrors 6 and 7. The laser beam L is efficiently outputted because it is reflected several times in the reach of the exciting light LD from the first semiconductor laser device 2 on the first laser reflecting surface 4A, and therefore has to travel several times back and forth in the reach of the exciting light LD in the first laser medium 4. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid-state laser oscillation device, and more particularly, to a solid-state laser oscillation device that excites a laser medium by excitation light to oscillate laser light.
[0002]
[Prior art]
Conventionally, as a solid-state laser oscillation device, a semiconductor laser that irradiates excitation light, a laser medium that is excited by the excitation light and oscillates laser light, and is located between the semiconductor laser and the laser medium and transmits the excitation light There is known a device provided with a reflecting surface for reflecting a laser beam and a front mirror and a rear mirror constituting a resonator.
In such a solid-state laser oscillation device, when the semiconductor laser irradiates the excitation light, the excitation light excites the laser medium to oscillate the laser light, and the oscillated laser light is resonated between the front mirror and the rear mirror. Later, it is output from the front mirror.
As such a solid-state laser oscillation device, a solid-state laser oscillation device described in Patent Literature 1 below is known. In Patent Literature 1, a laser between the front mirror and the rear mirror is used to output a laser beam having a predetermined output. By alternately reflecting the light path and arranging the semiconductor laser so that the path of the reflected laser light coincides with the optical axis of the semiconductor laser, the semiconductor laser is excited each time the laser light is reflected. Light is superimposed on the path of the laser light to increase the output of the laser light.
[0003]
[Patent Document 1]
JP-A-4-30484
[Problems to be solved by the invention]
However, when it is necessary to excite a laser medium with a semiconductor laser a predetermined number of times in order to output a laser beam of a predetermined output by the solid-state laser oscillation device of Patent Document 1, the same number of semiconductor lasers as the predetermined number of times of laser light It must be provided in accordance with the path, and it is difficult to design a compact solid-state laser oscillator that outputs high-power laser light.
In view of such a problem, the present invention is to provide a solid-state laser oscillation device suitable for miniaturization, capable of efficiently outputting laser light of a predetermined output even with a small number of semiconductor lasers.
[0005]
[Means for Solving the Problems]
That is, the solid-state laser oscillation device according to the present invention includes a first semiconductor laser that irradiates excitation light, a first laser medium that is excited by the excitation light to oscillate laser light, and a first semiconductor laser of the first laser medium. A first reflection surface that is provided on the side and transmits the excitation light and reflects the laser light oscillated by the first laser medium; and a second reflection surface that is provided at a position facing the first reflection surface and reflects the laser light. A second reflection surface, a front mirror and a rear mirror that form a resonator with the first laser medium interposed therebetween, and a laser light path between the front mirror and the rear mirror is defined by the first reflection surface and the second reflection surface. In a solid-state laser oscillation device that is alternately reflected,
At least one of the first reflecting surface and the second reflecting surface has a curved shape protruding toward the other reflecting surface, and the laser light is applied to the first reflecting surface of the first reflecting surface. In the irradiation range of the excitation light of the semiconductor laser, it is characterized in that it is more densely reflected toward the center of the irradiation range.
[0006]
According to the solid-state laser oscillation device of the present invention, the laser light passes more densely within the irradiation range of the excitation light of the first semiconductor laser on the first reflection surface, and further in the center of the irradiation range where the intensity of the excitation light is higher. Accordingly, the output of the laser light can be increased each time the laser light passes through the excitation light irradiation region in the first laser medium, so that the laser light can be efficiently extracted.
Therefore, the number of semiconductor lasers required to obtain a predetermined output laser beam can be reduced as compared with the conventional solid-state laser oscillation device, and the solid-state laser oscillation device can be downsized.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a solid-state laser oscillation device 1 according to a first embodiment of the present invention. The solid-state laser oscillation device 1 emits excitation light LD in directions facing each other. The first and second semiconductor lasers 2 and 3 provided, and a plate-shaped laser provided between the first and second semiconductor lasers 2 and 3 and excited by the excitation light LD to oscillate the laser light L. First and second laser media 4, 5, and a front mirror 6 and a rear mirror 7 provided so as to sandwich the first and second laser media 4, 5 and constituting a resonator for resonating the laser light L. I have.
When the first and second laser mediums 4 and 5 are excited by the solid-state laser oscillation device 1, the path of the laser light L is moved from the front mirror 6 to the rear mirror 7 as shown in FIG. The first and second laser light reflecting surfaces 4A and 5A formed on the second and fourth laser media 4 and 5 are alternately reflected.
Between the first semiconductor laser 2 and the first laser medium 4, there is provided a transmission member 8 provided on the optical axis of the excitation light LD and transmitting the excitation light LD. A sealing member 9 is provided between the first laser medium 4 and the first laser medium 4, and cooling water is circulated through a space formed by the transmitting member 8, the first laser medium 4 and the sealing member 9 to cool the first laser medium 4. It is supposed to do.
Further, a transmission member 8 is provided between the second semiconductor laser 3 and the second laser medium 5, and a seal member 9 is provided between the second laser medium 5 and the transmission member 8. The two laser mediums 5 are also cooled by the cooling water flowing between them.
[0008]
Here, the excitation light LD irradiated by the first and second semiconductor lasers 2 and 3 has an elliptical cross section, a slow axis having a small divergence angle in the longitudinal direction, and a fast axis having a large divergence angle in the short direction. The intensity of the pump light LD in the longitudinal direction is high near the optical axes of the first and second semiconductor lasers 2 and 3 as shown in FIG. In this embodiment, it is assumed that the optical axis of each of the semiconductor lasers 2 and 3 coincides with the center axis of the semiconductor laser itself.
For this reason, the first and second laser media 4 and 5 have a rectangular thin plate shape extending in the longitudinal direction of the cross section of the excitation light LD, and the irradiation range of the excitation light LD is transmitted through the transmission member 8. After that, irradiation is performed over the entire area of the first and second laser media 4 and 5 surrounded by the seal member 9.
The surface of the first laser medium 4 on the first semiconductor laser 2 side is coated with a dielectric multilayer film that reflects the laser light L while transmitting the excitation light LD from the first semiconductor laser 2. The first laser light reflecting surface 4A is a surface. The first laser light reflecting surface 4A has a curved shape formed with a predetermined curvature protruding toward the second laser medium 5, and the top of this curved shape and the optical axis of the first semiconductor laser 2 are aligned. They are provided to match.
On the other hand, the surface of the first laser medium 4 opposite to the first laser light reflecting surface 4A is coated with a dielectric multilayer film that reflects the excitation light LD from the first semiconductor laser 2 but transmits the laser light L. The first excitation light reflecting surface 4B is formed so as to be orthogonal to the optical axis of the first semiconductor laser 2.
When the first semiconductor laser 2 emits the excitation light LD, the excitation light LD excites the first laser medium 4 and oscillates the laser light L. When the light is reflected by the excitation light reflecting surface 4B, it is almost absorbed in the first laser medium 4.
Further, when the first laser medium 4 is excited and the laser light L is oscillated, the laser light L is thereafter transmitted through the first excitation light reflecting surface 4B and irradiated to the outside. The light is refracted by the first laser medium 4.
Similarly to the first laser medium 4, the second laser medium 5 also has a second laser light reflecting surface 5A and a second excitation light reflecting surface 5B, and the second laser light reflecting surface 5A is also a first laser medium. It has a curved surface shape protruding toward.
In this manner, by forming the curved surface shape protruding toward the second laser light reflecting surface 5A on the first laser light reflecting surface 4A, the incident angle of the laser light L reflected on the first laser light reflecting surface 4A and The reflection angle can be reduced as it approaches the top of the curved surface of the first laser light reflecting surface 4A.
[0009]
According to the solid-state laser oscillation device 1 having the above configuration, when the first and second semiconductor lasers 2 and 3 are irradiated with the excitation light LD, the first and second laser media 4 and 5 are excited and the laser light L is emitted. By oscillating and further arranging the first and second laser light reflecting surfaces 4A and 5A, the front mirror 6 and the rear mirror 7 as shown in FIG. 1, the path of the laser light L is changed to the first laser light reflecting surface 4A and the second laser light reflecting surface. The light is alternately reflected on the laser light reflecting surface 5A.
At this time, the excitation light LD radiated from the first semiconductor laser 2 is radiated over the entire surface of the first laser medium 4, and the path of the laser light L within the radiated range is the optical axis of the first semiconductor laser 2. The reflection is densely repeated in the vicinity, that is, in the center of the irradiation range. In other words, the path of the laser light L passes densely near the optical axis of the first semiconductor laser 2 where the intensity of the pump light LD is high, so that the output of the laser light L increases each time.
Therefore, according to the solid-state laser oscillation device 1 according to the present embodiment, the laser light L is reflected by the first laser light reflecting surface 4A and the second laser light reflecting surface 5A by the total number of times. The output can be increased, and the laser beam L can be extracted more efficiently than the front mirror 6.
In addition, by making the first laser light reflecting surface 4A curved, the incident angle of the laser light L incident on the first laser light reflecting surface 4A increases as the distance from the top of the curved shape of the first laser light reflecting surface 4A increases. Since it becomes large, it becomes easy to reflect the laser beam L to the front mirror 6 and the rear mirror 7.
[0010]
Here, in the conventional solid-state laser oscillation device described in Patent Document 1, the optical axis of the semiconductor laser and the path of the laser light reflected by the reflection surface are overlapped, so that the intensity of the excitation light by the semiconductor laser is highest. Although the laser medium was excited, it required the same number of semiconductor lasers as the number of times of reflection of the laser light in order to obtain laser light of a predetermined intensity.
On the other hand, in the solid-state laser oscillation device 1 according to the present embodiment, although the path of the laser light L does not coincide with the optical axis of the semiconductor laser, the efficiency of exciting the laser light L slightly decreases, but the two semiconductor lasers Can excite the laser medium a plurality of times, respectively, so that the number of required semiconductor lasers can be reduced as compared with the solid-state laser oscillation device of Patent Document 1.
Therefore, according to the present embodiment, in order to output the laser light L having the same output, it is sufficient to provide a smaller number of semiconductor lasers as compared with the related art, so that a small solid-state laser oscillation device 1 can be obtained.
[0011]
If the transmitting member 8 in this embodiment is changed to a cylindrical lens that focuses the first axis of the excitation light LD, the intensity of the excitation light LD irradiated on the laser medium can be increased, and the laser light can be more efficiently emitted. Can be output.
Further, the solid-state laser oscillation device 1 of the present embodiment is provided with two semiconductor lasers and two laser media. However, it is possible to increase the numbers of these, and in this case, the first laser light reflection in FIG. The laser beam L reflected by the surface 4A may be reflected toward another laser medium provided adjacent to the second laser medium 5, or the angle of the rear mirror 7 may be changed to change the first laser medium 4 May be reflected toward another laser medium provided adjacent to the laser medium.
[0012]
FIG. 3 shows a second embodiment of the solid-state laser oscillation device 1 according to the present invention. The solid-state laser oscillation device 1 of the present embodiment comprises first and second semiconductor lasers 12 and 13 and first and second semiconductor lasers. A laser medium 14 for oscillating a laser beam L provided between the two semiconductor lasers 12 and 13 is provided, and a front mirror 15 and a rear mirror 16 constituting a resonator provided so as to sandwich the laser medium L.
The laser medium 14 has a first laser light reflecting surface 14A as a first reflecting surface coated with a dielectric multilayer film that transmits the excitation light LD from the first semiconductor laser 12 and reflects the laser light L. Is formed on the opposite side of the first laser light reflecting surface 14A, also coated with a dielectric multilayer film that transmits the excitation light LD from the second semiconductor laser 14 and reflects the laser light L. A second laser light reflecting surface 14B as a surface is formed.
Also in this embodiment, the cross section of the excitation light LD emitted from the first and second semiconductor lasers 12 and 13 has an oval shape. The laser medium 14 has a thin plate shape in the depth direction of FIG.
Further, the first and second laser light reflecting surfaces 14A and 14B have a curved shape formed with a predetermined curvature protruding in a direction facing each other, and the top of each curved surface and the first and second semiconductor lasers. The optical axes of 12 and 13 coincide with each other.
The irradiation range of the excitation light LD by the first and second semiconductor lasers 12 and 13 is the entire area of the first and second laser light reflecting surfaces 14A and 14B. The excitation light LD emitted from the semiconductor laser 12 is almost absorbed by the first laser light reflecting surface 14A after being transmitted, and before reaching the second laser light reflecting surface 14B.
Here, in the present embodiment, a cooling water passage (not shown) is provided so as to sandwich the laser medium 14 in the depth direction of the drawing in order to cool the laser medium 14, and the cooling medium is circulated through the cooling water passage. 14 is cooled.
Further, a cylindrical lens may be provided between the first and second semiconductor lasers 12 and 13 and the laser medium 14 so as to converge the first axis of the excitation light LD.
[0013]
According to the solid-state laser oscillation device 1 having the above configuration, similarly to the solid-state laser oscillation device 1 in the first embodiment, when the first and second semiconductor lasers 12 and 13 are irradiated with the excitation light LD, the laser medium 14 is irradiated. Is excited to oscillate the laser light L, and furthermore, the first and second laser light reflecting surfaces 14A and 14B, the front mirror 15, and the rear mirror 16 are arranged as shown in FIG. The light is alternately reflected on the laser light reflecting surface 4A and the second laser light reflecting surface 5A.
At this time, the excitation light LD irradiated from the first semiconductor laser 12 is irradiated over the entire surface of the laser medium 14, and the path of the laser light L within the irradiation range is near the optical axis of the first semiconductor laser 12, That is, reflection is densely repeated at the center of the irradiation range. In other words, the path of the laser light L passes densely near the optical axis of the first semiconductor laser 2 where the intensity of the pump light LD is high, so that the output of the laser light L increases each time.
Therefore, according to the solid-state laser oscillation device 1 of the present embodiment, the laser light L is reflected by the first laser light reflecting surface 14A and the laser light L by the total number of times of reflecting by the second laser light reflecting surface 14B. The output can be increased, and the laser beam L can be extracted more efficiently than the front mirror 15.
Further, in this embodiment, since only one laser medium is used, the solid-state laser oscillation device 1 can be further reduced in size as compared with the first embodiment.
In the first and second embodiments, one semiconductor laser is provided for each laser light L reflecting surface, but one of the semiconductor lasers may be omitted.
For example, in the case where the second semiconductor laser 3 is omitted in the first embodiment, the second laser medium 5 may be omitted and a simple reflecting mirror for reflecting the laser light L may be provided as the second laser light reflecting surface. , The laser beam L can be oscillated.
[0015]
【The invention's effect】
According to the solid-state laser oscillation device of the present invention, the laser light is reflected a plurality of times within the irradiation range of the excitation light of the first semiconductor laser on the first reflection surface. Is passed a plurality of times, and the laser light can be output efficiently.
In addition, a laser beam having a predetermined output can be efficiently obtained with a smaller number of semiconductor lasers than a conventional solid-state laser oscillation device, and the solid-state laser oscillation device can be downsized.
[Brief description of the drawings]
FIG. 1 is a plan view showing a first embodiment of the present invention.
FIG. 2 is a diagram showing an intensity distribution of an excitation light LD by a semiconductor laser.
FIG. 3 is a plan view showing a second embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 solid-state laser oscillator 2 first semiconductor laser 3 second semiconductor laser 4 first laser medium 4A first laser light reflecting surface 5 second laser medium 5A second laser light reflecting surface 6 front mirror 7 rear mirror

Claims (3)

A first semiconductor laser that emits excitation light, a first laser medium that is excited by the excitation light and emits laser light, and is provided on the first semiconductor laser side of the first laser medium and transmits the excitation light. A first reflecting surface for reflecting laser light oscillated by the first laser medium, a second reflecting surface provided at a position facing the first reflecting surface for reflecting laser light, and the first laser medium. A solid state laser oscillating device comprising a front mirror and a rear mirror forming a resonator with the resonator interposed therebetween, wherein a laser light path between the front mirror and the rear mirror is alternately reflected by a first reflection surface and a second reflection surface At
At least one of the first reflecting surface and the second reflecting surface has a curved shape protruding toward the other reflecting surface, and the laser light is applied to the first reflecting surface of the first reflecting surface. A solid-state laser oscillation device characterized in that, within the irradiation range of the excitation light of the semiconductor laser, the light is more densely reflected toward the center of the irradiation range. A second semiconductor laser is provided on a side opposite to the first reflection surface with the second reflection surface as a center, and a second laser medium 5 is provided on the first reflection surface side. 2. The solid-state laser oscillation device according to claim 1, wherein the light is transmitted through the second reflection surface and is applied to the second laser medium to oscillate the laser light. 3. The first reflection surface and the second reflection surface are arranged on a pair of opposing surfaces of the first laser medium, and a second semiconductor laser is provided on the opposite side of the first laser medium from the first semiconductor laser. 2. The solid-state laser oscillation device according to claim 1, wherein the excitation light from the second semiconductor laser is transmitted through the second reflection surface and is applied to the first laser medium to oscillate the laser light.

Images