JPH04162581A - Solid-state laser oscillator - Google Patents

Abstract

PURPOSE:To obtain a solid-state laser oscillator having small decrease in a wavelength conversion efficiency by providing a first high reflecting mirror, a second output mirror, and a second high reflecting mirror for forming a second optical resonator, and converting a wavelength by switching a predetermined position of the second mirror. CONSTITUTION:A first high reflecting mirror 20 and a first output mirror 21 are provided coaxially with a solid state laser medium 15 at both sides of a solid state laser medium 15, and an optical resonator is formed. A guide rail 23 is provided perpendicularly to an optical passage 22 at the passage 22 between the medium 15 and the mirror 21, and a second output mirror 24 made of a harmonic mirror is bent perpendicularly to the passage to form a refractive optical passage 25 at 45 degrees on the rail. A second high reflecting mirror 26 is provided coaxially on the rail at the passage 25 to be telescoped to the passage 23 by driving to the mirror 26 side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to a solid-state laser oscillation device, and particularly to a device that generates two different wavelengths.

(Prior Art) In laser film forming processing, processing using three different wavelengths is performed in order to improve the electrical characteristics of the formed thin film. The configuration of an apparatus for obtaining three wavelengths has been to provide two laser oscillators each outputting a separate wavelength, or to replace the optical system for each wavelength.

However, in the former case, the device becomes large and impractical, and in the latter case, it is necessary to adjust the optical axis each time it is replaced, and scanning becomes complicated.

Instead of the above configuration, it is also conceivable to create two resonator optical paths using a switching means and output different wavelengths from each resonator optical path. For example, a conventional technique for creating two resonator optical paths using a switching means is a technique that obtains different pulse widths instead of three wavelengths;
The one disclosed in No. 7 is known. This technology is the second
As shown in the figure, an output mirror (2) is provided at one end of a laser substance (1), and an optical body (3) for changing the optical path is provided at the other end. The optical body (3) is designed to rotate around a fulcrum (4), and when the optical body (3) rotates to the position shown by the solid line, a polarizing element (6) and a Pockels cell effect are used to change the optical path (5). An electro-optical element (7) and a first high-reflection mirror (8) are sequentially provided. When the optical body (3) is rotated to the position shown by the broken line, a second optical path (9) is provided. A highly reflective mirror (10) is provided.

Note that (11) is a microswitch that senses the changed position of the optical body (3).

In the above configuration, the rotation of the optical body (3) creates two resonator optical paths, one passing through the changing optical path (5) and the other passing through the changing optical path (9), and laser beams with different pulse widths are sent to the output mirror. (2).

(Problem to be Solved by the Invention) In the configuration shown in FIG. 2 above, the polarizing element (6) and the electro-optical element (7) are removed from the optical path, a nonlinear crystal is provided in their place, and the output mirror (2) is Highly reflective mirror, and
, two different wavelengths can be obtained by replacing the second high-reflection mirrors (81, (10) with output mirrors with different characteristics. However, the presence of the optical body (3) reduces the harmonic conversion efficiency. In addition to reducing the laser material f, similar to the method of replacing each optical system above,
There was a problem in that conversion efficiency decreased due to l). In other words, since a nonlinear crystal is usually provided between the laser material and the output mirror, the second harmonic, which is partially converted from the fundamental wave by passing through the nonlinear crystal, is directly emitted to the outside from the output mirror. Ru. The fundamental wave reflected from the output mirror is not converted. A part of it is converted into second harmonics again by the nonlinear crystal, but in order to return to the output mirror, the light must pass through the laser material twice or be reflected by a high-reflection mirror. Optical loss increases. For example, in the case of a YAG laser, the fundamental wave is 20
Compared to the output of W, the second harmonic output was only 5W. The present invention was made to solve this problem, and an object of the present invention is to provide a solid-state laser oscillation device in which wavelength conversion efficiency is less reduced.

[Structure of the invention] (Means and effects for solving the problem) A solid-state laser medium, a first high-reflection mirror provided at one end of the solid-state laser medium, and a first high-reflection mirror provided at the other end of the solid-state laser medium. a first output mirror that forms a first optical resonator with the first high-reflection mirror; a second output mirror that deflects; a wavelength conversion element that is provided on the deflected optical path and converts the wavelength of the laser light in the first optical resonator; and a wavelength conversion element that converts the laser light transmitted through the wavelength conversion element. a second high-reflection mirror that reflects toward the element side and forms a second optical resonator with the first high-reflection mirror and the second output mirror; The wavelength is converted by switching the position.

(Examples) Hereinafter, the present invention will be described in detail with reference to the drawings showing examples. FIG. 1 shows an embodiment of the present invention, which has a solid-state laser medium (15) made of Nd''YAG crystal, and a first high-reflection mirror (20) on both sides of this solid-state laser medium (15).
) and a first output mirror (21) are provided coaxially with the solid-state laser medium (15) to form an optical resonator. A guide rail (23) is provided perpendicularly to the optical path (22) between the solid-state laser medium (15) and the first output mirror (21). A second output mirror (24) made of a harmonic mirror is provided on the guide rail at an angle of 45 degrees to bend the optical path at right angles to form a refracted optical path (25). Refracted optical path (2
5), a second high reflection mirror (26) is coaxially provided on the guide rail. The second output mirror (24) engages with the driver (27) and is driven along the guide rail (23) toward the second high-reflection mirror (26).
It enters and leaves the optical path (23). In addition, a nonlinear crystal (28) is coaxial with the refracting optical path (25) between the second output mirror (24) and the second high-reflection mirror (26). It is installed on the guide rail. KDP, KTP, LBO, etc. are used as this nonlinear crystal (27).In the above configuration, the first output mirror (21) is generated between this mirror and the first high reflection mirror (20). The fundamental wave of the laser beam (30) (
ω), that is, it is a reflecting mirror that transmits a wavelength of 1.06 μm with a predetermined transmittance. In addition, the first high-reflection mirror (
20) is formed to have high reflection with respect to the fundamental wave (ω). On the other hand, the second output mirror (24) has a characteristic of highly reflecting the fundamental wave (ω) and transmitting the second harmonic (2ω) of the fundamental wave. The second high reflection mirror (26) is formed to have high reflection for the fundamental wave (ω) and the second harmonic (2ω).

Next, the operation of the above configuration will be explained. Second output mirror (
24) is outside the optical path (22) indicated by the broken line in the figure,
The laser oscillates only in the optical resonator between the first high reflection mirror (20) and the first output mirror (21), and the first output mirror (21)
The fundamental wave (ω) is output from. In this way, the fundamental wave (ω)
When the driver (27) is operated and the second output mirror (24) is placed in the optical path (22) while outputting, the fundamental wave (ω) is A refracted optical path (25) is formed. With this formation, the fundamental wave (ω) is transformed into a nonlinear crystal (2
8) and is converted into a second harmonic (2ω) at a predetermined ratio. The converted second harmonic (2ω) is reflected by the second high reflection mirror (26) together with the unconverted fundamental wave (ω), and when passing through the nonlinear crystal (28) again, the second harmonic (2ω) is The second harmonic (2ω) is transmitted as is, but a part of the fundamental wave (ω) is converted back into the second harmonic (2ω). The second harmonic (2ω) converted in this way is sent to the second output mirror (24
) and is extracted as laser output. On the other hand, the unconverted component is similarly reflected by the second output mirror (24) and returned to the first high reflection mirror (20), and the above conversion and reflection are repeated. Note that since the nonlinear crystal (28) is provided within the fundamental wave laser resonator, the power density of the fundamental wave within the nonlinear crystal is clearly higher than when it is provided outside the resonator. As a result, a high output second harmonic is obtained.

[Effects of the Invention] As explained above, since the converted harmonics do not pass through any optical path other than the second high reflection mirror and the second output mirror, the loss due to the optical system is significantly reduced. As a result, for example, YAG
In the laser beam, a second harmonic of 10 W was obtained for a fundamental wave of 20 W, and a conversion efficiency more than three times higher than that of the conventional method was achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is a configuration diagram for explaining a conventional example. (15)...Solid laser medium (20)...First high reflection mirror (21)...First output mirror (24)...Second output mirror (26)...First 2 High reflective mirror (28)...Nonlinear crystal

Claims (1)

[Claims] A solid-state laser medium, a first high-reflection mirror provided at one end of the solid-state laser medium, and a first high-reflection mirror and a first optical resonator provided at the other end of the solid-state laser medium. a second output mirror that is provided in the optical path between the first output mirror and the solid-state laser medium to deflect the optical path; and a second output mirror that is provided in the deflected optical path. a wavelength conversion element that converts the wavelength of the laser light in the first optical resonator; and a wavelength conversion element that reflects the laser light transmitted through the wavelength conversion element to the wavelength conversion element side.
1. A solid-state laser oscillation device comprising: a high-reflection mirror; a second output mirror; and a second high-reflection mirror forming a second optical resonator.