JPH0478178A - Slab-type solid-state laser oscillation - Google Patents

Abstract

PURPOSE:To make an optical going path different from an optical returning path and to eliminate a part which does not contribute to laser oscillation from the inside of a laser element by arranging a laser element having an incidence/projection end surface which is vertical to two parallel optical mirrors and a total of four total reflection and partical reflection mirrors to make an incident angle and a projection angle to the laser element equivalent. CONSTITUTION:A laser light incidence/projection end surface is arranged in a slab-type solid state laser element 1 at a right angle to two optical mirrors, and a laser light incidence/projection angle theta to a normal thereof is made 19 deg. and total reflections are carried out four times each for going and returning paths. A total of four mirrors of three total reflection mirrors 2a, 2b, 2c and one partially reflecting mirror 3 are used. When a lamp 4 is arranged in a width direction of the laser element 1, an optical path can be designed without restriction to an electrode part of the lamp 4. Since light reflected by an excitation light reflecting mirror 10 enters the laser element 1, excitation of the laser element 1 becomes more uniform. A part 7 which does not contribute to oscillation produced in a going path 5-1 becomes an optical path of a returning path 5-2 of laser light and is eliminated in an amplification process of laser light.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a slab-type solid-state laser device, and particularly to a slab-type solid-state laser oscillator.

[Conventional Technology Figure 4 is a schematic vertical cross-sectional view showing the configuration of a typical conventional slab-type solid-state laser oscillator, and an example of this type of laser oscillator is the one disclosed in Japanese Patent Publication No. 63-67346. It will be done. FIG. 5 is a schematic cross-sectional view of a slab-type solid-state laser device showing the arrangement of lamps for exciting the slab-type solid-state laser oscillator of FIG. In Figures 4 and 5, 1 is a slab-type solid-state laser element, 2 is a total reflection mirror, 3 is a partial reflection mirror, 4 is an excitation lamp, 5 is a laser beam optical path, 6 is a laser output, and 7 is a slab type The parts of the mounted laser device that do not contribute to laser oscillation, 8 is a cooling water channel for cooling the slab-type solid-state laser device, 9 is an ultraviolet light cut filter and water channel forming plate, 10 is an excitation light reflector, and 11 is a heat insulator. It is a material. The slab-type solid-state laser device 1 includes two mutually parallel optical mirror surfaces 1a and 1b arranged so as to form an optical path through which the laser beam passes through one or more internal reflections, and a mirror 3.4. Opposite to -Boo light output surface IC21
It has d. The laser beam input/output end faces 1c and ld are set at lIJ! with respect to the optical path to prevent reflection loss. The optical path is slanted, and the optical path forms a Brewster angle θ with respect to the normal to the laser light input/output end faces 1c and 1d. In addition, cooling water B8
- Cool the element 1 by surrounding it with pure water,
When the excitation lamp 4 is turned on and excitation light is irradiated into the laser element 1, the Nd3- ions in the laser element 1 are prevented from deforming due to heat accompanying laser oscillation. Excited to a higher energy level. Fluorescence is emitted when the energy level falls from this high energy level to a low energy level, and this fluorescence further becomes stimulating light and causes stimulated emission of laser light. In the above oscillator, the light reflected by the total reflection mirror 2 passes through the optical path 5.
It is refracted by the end face IC of the laser element 1 and enters the laser element 1, and reaches the other end face 1d while causing total reflection on the two optical mirror surfaces 1a and 1b, and is refracted again to form a partially reflecting mirror. 3, and the light reflected by the mirror 3 is adjusted so that it passes through the same optical path 5 again. Therefore, while the light travels back and forth on this optical path 5, it is amplified and a laser output 6 is obtained. According to such a slab-type solid-state laser device, the beam is totally reflected by the two mutually parallel optical mirror surfaces 1a and 1b of the laser element and propagates throughout the laser element 1, so that the thermal lens effect is effectively eliminated. It has been considered suitable as a high-energy oscillator because it offsets the above, improves energy extraction efficiency, and heam quality. Problems to be Solved by the Invention l Conventional slab-type solid-state laser devices have attracted attention from an early stage due to the advantages mentioned above6 However, as shown in FIG. The laser light optical path 5 through which the laser beam passes does not occupy the entire inside of the laser element 1. That is, even if the excitation light from the lamp 4 is received, there may be a portion 7 that does not contribute to laser oscillation. Therefore, in the conventional slab-type solid-state laser device configured as described above, the portion 7 that does not contribute to laser oscillation is
There is a problem in that the larger the proportion of the total laser element, the lower the energy extraction efficiency. The present invention was made to solve the above problems, and therefore aims to improve energy extraction efficiency and laser output in laser oscillation. [Means for Solving the Problem] The above problem is caused by a portion 7 that does not contribute to laser oscillation because the outgoing and returning paths of the light are unchanged on the same optical path 5, as shown in FIG.
This problem occurs because this part only generates heat due to the excitation light and does not contribute to oscillation. In order to solve the above-mentioned problems, the present invention aims to ensure that the laser beam path is
On the way out, t! iL path is different, and moreover, two mirrors are arranged for one input/output end face so that the incident (output) angle of the forward path and the exit (incident) angle of the backward path of the laser beam optical path are equal. The optical path is designed to be symmetrical between the forward path and the return path, thereby eliminating portions that do not contribute to Laser oscillation. That is, the laser oscillator of the present invention includes a slab-type solid-state laser element having two mutually parallel optical mirror surfaces and laser light input/output end surfaces not perpendicular to the optical mirror surfaces;
It consists of a mirror that allows the laser beam to enter and exit the solid-state laser element, and the laser beam solidifies while performing one or more total internal reflections on the optical mirror surface. The area formed by the outgoing path and the incoming path substantially occupies the entire solid-state laser element. In the slab-type solid-state laser device of the present invention, the mirror of the laser oscillator is composed of one partial reflection mirror and three total reflection mirrors. Further, the mirror of the laser oscillator is arranged so that the laser beam incidence angle and the laser beam output angle are less than 90 degrees symmetrical at the laser light input/output end face of the slab-type solid-state laser element. y).

[Effect]

The present invention consists of two mutually parallel optical mirror surfaces (total reflection surfaces).
By using an oscillator configuration in which a laser element having an incident and output end face perpendicular to the laser element and four total reflection and partial reflection mirrors are arranged so that the incident angle and the output angle with respect to the laser element are equal, the optical path 5 is By making the forward and backward paths different, the portion that does not contribute to laser oscillation from inside the laser element was eliminated. As a result, the area consisting of the forward and backward paths of the laser beam substantially occupies the entire solid-state laser element, and it is possible to improve energy extraction efficiency and laser output.

【Example】

Hereinafter, the present invention will be described in detail based on the drawings. Reference numbers are common to FIGS. 4-5. FIG. 1 is a schematic vertical cross-sectional view showing a slab-type solid-state laser oscillator of the present invention, and FIG. 2 is a diagram showing the slab-type solid-state laser oscillator of the present invention in which the slab-type solid-state laser oscillator of FIG. 1 and a lamp for exciting it are arranged. 1 is a schematic cross-sectional view of a laser device; the numbers shown are common to all figures; FIG. In this example, the thickness is 6 mm, the width is 34 mm, and the total length is 132 mm.
mm rectangular parallelepiped, N d "1 degree 1, 1 atom?g YA
G crystal was used as a laser medium. In the slab-type solid-state laser device 1, two optical mirror surfaces 1
Laser light input/output end faces 1c, 1d perpendicular to a, 1b
, the laser beam incidence and output angle θ with respect to the normal line of the end faces 1c and 1d is 19 degrees (71 degrees when converted to the human output angle with respect to the total reflection surface), and the number of total reflections is 4 times each in the forward and return directions. . When the present invention is realized using a conventional lamp arrangement as shown in FIG. 3 using a total of four mirrors, three total reflection mirrors 2a, 2b, and 2c and one partial reflection mirror 3, As shown in FIG. 3, the laser light input/output optical path 5 is limited to overlap with the S[i portion of the lamp 4, so it is difficult to form an oscillation optical path. Although this limit largely depends on the design, as shown in FIG. 3, the laser beam input/output angle θ with respect to the normal to the laser beam input/output end face is about 15 degrees at maximum. Therefore, as shown in FIG. 2, the arrangement of the rung 4 with respect to the laser element 1 was changed to eliminate the above-mentioned disadvantage. That is, by arranging the lamp 4 in the width direction of the laser element 1, the optical path 5 can be designed without being limited by the electrode portion of the lamp 4. Furthermore, a laser element 1 and a lamp 4 as shown in FIG.
In the arrangement, the light from the lamp 4 does not directly enter the laser element 1, but the light reflected by the excitation light reflecting mirror 1° enters the laser element 1, so that the excitation of the laser element 1 becomes more uniform. In the mirror arrangement shown in FIG. 1, the portion 7 generated on the outgoing path 5-1 that does not contribute to oscillation becomes the optical path of the laser beam on the incoming path 5-2. Therefore, the portion 7 that does not contribute to laser oscillation is
This is eliminated during the laser beam amplification process. This shows that the entire volume of the laser element can effectively contribute to oscillation, and there is no reduction in energy extraction efficiency due to the presence of the portion 7 that does not contribute to laser oscillation. Therefore, the laser output 6 from the laser element 1 can be improved. In this example, there are three total reflection mirrors and one partial reflection mirror meter 4.
It is possible to use one or more configurations of the total reflection mirror or the partial reflection mirror within the scope of the present invention. Effect of the Invention 1 As described above, according to the present invention, the entire volume of the slab-type solid-state laser element can be effectively contributed to oscillation, and improvements in energy extraction efficiency and laser output can be achieved.

[Brief explanation of the drawing]

Figure 1 shows the slab-type solid-state oscillator of the present invention? It is a longitudinal section Q diagram shown. Figure 2 shows the arrangement of lamps for exciting the slab-type solid-state oscillator shown in Figure 1.
! It is a cross-sectional diagram. FIG. 3 is a schematic plan view illustrating a case where the present invention is applied to the slab-type solid-state oscillator of FIG. 1 with a conventional lamp weight capacity. FIG. 4 is a schematic vertical cross-sectional view showing the configuration of a typical conventional slab-type solid-state laser device. FIG. 5 is a schematic cross-sectional view of a slab-type solid-state laser device showing the arrangement of lamps for exciting the slab-type solid-state laser oscillator of FIG. (Left space on this page) In the figure, numbers indicate the following elements. 1: Nislab type solid-state laser element, 2: Total reflection mirror 3: Partial reflection mirror 4: Excitation lamp, 5: Laser beam optical path, 5-1=outward path of the optical path, 5-2; return path of the optical path, 6 : Laser output, 7: Area that does not contribute to laser oscillation caused by overlapping of the round-trip optical paths within the laser element, 8: Cooling water channel, 9: Ultraviolet light cut filter/channel forming plate, 10:
Excitation light reflecting mirror, 11: Heat insulating material.

Claims (4)

[Claims] (1) Consists of a slab-type solid-state laser element having two mutually parallel optical mirror surfaces and a laser beam input/output end face perpendicular to the optical mirror surfaces, and a mirror that allows the laser beam to enter and exit the solid-state laser element. The outgoing path and the incoming path through which the laser beam passes through the solid-state laser element while performing one or more total internal reflections on the optical mirror surface are formed in different locations, so that the area consisting of the outgoing path and the incoming path is substantially the solid-state laser element. A slab-type solid-state laser oscillator that occupies the entire area. (2) The slab-type solid-state laser oscillator according to claim 1, wherein the mirror of the laser oscillator is composed of one partial reflection mirror and three total reflection mirrors. (3) The mirror of the laser oscillator is arranged so as to have a symmetrical laser beam incident angle and laser beam output angle of less than 90 degrees at the laser beam input/output end face of the slab-type solid-state laser element. The slab-type solid-state laser oscillator according to claim 1, characterized in that: (4) A slab-type solid-state laser device, wherein a lamp for exciting the slab-type solid-state laser oscillator according to claim 1 is arranged in the width direction of a solid-state laser element.