JPH0265283A - Solid-state laser - Google Patents

Abstract

PURPOSE:To enable a laser medium to efficiently absorb LD light rays so as to improve an oscillation energy efficiency by a method wherein an optical guide, which enables the light rays of a semiconductor laser to be obliquely incident on the laser medium, is provided. CONSTITUTION:An exciting light ray 12 for an LD1 is made to be obliquely incident on a laser medium 2. In result, the optical path inside the laser medium 2 becomes long, so that the light rays 12 are effectively absorbed in the laser medium. Furthermore, a part of the exciting light rays 12 reflected by the surface of the laser medium 2 is reflected again by a reflecting surface 71 of an optical guide 7 to make its traveling direction changed and made to be incident on the laser medium 2 again. As mentioned above, the exciting light rays 12 are almost absorbed in the laser medium 2 while they are reflected two or more times in a triangular space constituted with the surface of the laser medium and the reflecting surface 71. Therefore, the LD light ray has a little variation in wavelength and also in an absorbing coefficient, but the laser medium can be effectively excited. The heat generated in the laser medium is transmitted to a cooler 8 through a thin filler 61 and a holder 6 and finally radiated outside from a heat radiating fin 81.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an excitation structure of a solid-state laser that is excited by light from a semiconductor element such as a semiconductor laser (LD).

[Conventional technology]

FIG. 7 shows, for example, U.S. Pat. No. 3,624,545 (U, S
, Patent 3,624,545), and in the figure, 1 is an LD, 2 is a laser medium such as a YAG round bar, 3,
4 is a total reflection film and a partial reflection film formed on the end face of the laser medium 2, and 5 is a reflecting mirror.

Next, the operation will be explained.

The excitation light emitted from the LDI enters the laser medium 2,
Absorbed. The light that has passed through without being absorbed is reflected by the reflecting mirror 5 and enters the laser medium 2 again. The energy of the absorbed light becomes oscillated by the optical resonator surrounded by the partial reflection film 4 and the total reflection film 3, and part of it becomes laser light and is emitted to the outside.

The absorption coefficient of the laser medium 2 for LDI light has a strong wavelength dependence, for example, 0.75 for 808.5 nm.
n+m-', 0.0 for 802 nm. lmm-'. In order to effectively absorb light into a compact laser medium, it was necessary to precisely control the spectrum of LDI.

[Problem to be solved by the invention]

Since conventional solid-state lasers are configured and implemented as described above, it is difficult to make the laser medium completely absorb the light from the laser diode, and therefore there is a problem that the energy efficiency of laser oscillation is low.

Further, conventional solid-state lasers have the problem that heat dissipation from the laser medium is insufficient, and the quality of the beam deteriorates as the output increases.

This invention was made to solve the above-mentioned problems, and aims to provide a solid-state laser that can efficiently absorb LD light and improve the energy efficiency of oscillation.

[Means to solve the problem]

The solid-state laser according to the present invention includes a light guide that allows light from a pumping semiconductor laser to enter the laser medium obliquely.

[Effect]

In this invention, since the configuration is provided with a light guide that allows the light of the semiconductor laser to enter the laser medium obliquely, the LD light is efficiently absorbed by the laser medium and the oscillation energy efficiency is improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a solid-state laser according to an embodiment of the present invention, in which 1 is an LD, 11 is a mount, 12 is an excitation light, 2 is a laser medium, 21 is an AR (anti-reflection) film,
30 is a PR (partial reflection) mirror, 4 is a TR (total reflection) film, 6 is a holder, 61 is a filler, 7 is a light guide, 71 is a reflective surface, 8 is a cooler, 81 is a radiation fin, 9 is a laser This is the output.

FIG. 2 is a diagram of the solid-state laser of FIG. 1 viewed from the end face direction, and as shown in this diagram, a plurality of LDIs are arranged in the circumferential direction.

FIG. 3 is a diagram showing the movement of the excitation light 12 in the solid-state laser of FIG. 1 in comparison with the movement of the excitation light in a conventional solid-state laser.

Next, the operation will be explained.

Excitation light 12 of the LDI enters the laser medium 2 obliquely.

As a result, the optical path within the laser medium becomes longer (approximately 1.4 times that of the conventional example in the figure) and is effectively absorbed. Furthermore, the excitation light 12 that has been partially (approximately 20%) reflected by the surface of the laser medium is reflected again by the reflective surface 71 of the light guide 7, changed direction, and enters the laser medium 2 again. In this way, the laser medium 2
The excitation light 12 is reflected multiple times in the triangular space formed by the surface of the laser and the reflecting surface 71, and most of the excitation light 12 is absorbed by the laser medium. Therefore, even if there are some variations in the wavelength of the LD light and variations in the absorption coefficient, the laser medium can be effectively excited. FIGS. 3(a) and 3(b) show the movement of the excitation light of the solid-state laser of this embodiment and the conventional solid-state laser, respectively. Since the excitation light of LDI is generally linearly polarized,
If the LDI is installed so that the excitation light becomes a P wave as shown in FIG.

The energy thus absorbed by the laser medium 2 is oscillated in a resonator made up of the TR film 4 and the PR mirror 30, and a portion is extracted as a laser output 9.

The heat of the laser medium 2 is transferred to the thin filler 61. The heat passes through the holder 6 by conduction, flows to the cooler 8, and finally reaches the heat dissipation fins 81.
released from. The heat of LDl is also mount 11. It is similarly efficiently cooled via the holder 6. Filler 61
By making the holder 6 transparent to the excitation light and making the inner surface of the holder 6 a reflector, the absorption efficiency of the excitation light is further improved.

In this way, this embodiment includes a guide surface that makes the LD light enter the laser medium obliquely and makes the reflected light from the surface of the laser medium enter the laser medium again, so that the polarization plane of the LD is relative to the laser medium. Since the LD is mounted at a corner to generate P waves, a solid-state laser with high oscillation energy efficiency can be obtained, and the laser medium and semiconductor laser can be efficiently cooled in terms of heat conduction. As a result, a solid-state laser with excellent beam quality can be obtained.

In the above embodiment, the light guide 7 is formed into a conical shape, but it may be formed in the shape of a hole with a reflective surface 71, or may be formed of an optical fiber. Also LDl's mount 11
The structure of can be modified in various ways.

Figure 4 (al, tel, (C1) are diagrams showing main parts of other embodiments of the present invention, respectively. Figure 4 (al is a straight hole shape, Figure 4 (bl is a bent or curved hole) Hole-shaped, FIG. 4 (0) shows the optical fiber 120 connected to the light guide introduction hole 122
This is an example of forming a light guide through the

Furthermore, the arrangement of the LDI is as shown in FIG.
It is possible to increase the output by setting a plurality of pieces in the axial direction.

Furthermore, in each of the above embodiments, the laser medium 2 is a round bar.
The present invention is also effective for so-called slab-type lasers in which a plate-shaped slab-type laser medium is used and the laser optical axis undergoes total internal reflection multiple times. FIG. 6 is a diagram showing an embodiment in which the present invention is applied to a slab laser, in which FIG. 6(a) is a cross-sectional view thereof, and FIG. 6 (bl is a vertical cross-sectional view thereof. 2
0 is a slab type laser medium, and 40 is a TR mirror. As shown in the figure, a plurality of LDs are arranged in a plurality of rows in the width direction of the slab type laser medium 20.

〔Effect of the invention〕

As described above, according to the present invention, in the solid-state laser,
Since the configuration includes a light guide that allows the LD light to enter the laser medium obliquely, the optical path of the excitation light in the laser medium becomes longer, which has the effect of improving oscillation energy efficiency.

[Brief explanation of the drawing]

1 and 2 are a cross-sectional view and a longitudinal sectional view showing a solid-state laser according to an embodiment of the present invention, and FIG. 3 shows the movement of excitation light in the solid-state laser of this embodiment compared to the conventional solid-state laser Diagrams shown in comparison with the movement of light, Figures 4, 5, and 6
Figures 7 and 7 are diagrams showing main parts of other embodiments of the present invention, respectively.
The figure shows the configuration of a conventional solid-state laser. 1 is LD, 11 is mount, 12 is excitation light, 2 is laser medium, 20 is slab type laser medium, 30 is PR (partial reflection) mirror, 4 is TR (total reflection) film, 40 is TR mirror, 6 is holder, 61 is a filling, 7 is a light guide, 71 is a reflective surface, 8 is a cooler, 81 is a radiation fin, and 9 is a laser output. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A solid-state laser in which a solid-state laser medium is excited by a semiconductor laser, characterized in that the solid-state laser is provided with a light guide that allows light from the semiconductor laser to enter the solid-state laser medium obliquely.