JPS6288386A - Semiconductor-laser exciting solid-state laser - Google Patents

Abstract

PURPOSE:To implement a solid state laser characterized by large output, low threshold value, compact configuration and high conversion efficiency, by coating the side surface other than a gap, through which exciting light from semiconductor lasers at the side surface of a solid-state material is inputted, with a reflection preventing film, and providing reflecting mirrors at both end surfaces of the solid-state material, which emit laser oscillated light. CONSTITUTION:A plurality of semiconductor lasers 2 are attached to one side surface of a long, pillar shaped Nd:YAG crystal 1. Only a gap 3, through which the exciting light from the semiconductor laser 2 is inputted, is made to remain, and the other part is coated with a reflecting film 4. Reflecting mirrors 5 are formed at both end surfaces of the Nd:YAG crystal 1 so that laser oscillation can occur. At this time, in order to utilize the exciting light from the laser effectively and to avoid loss in light at both end surfaces, it is advantageous to confine the exciting light within a plane vertical to oscillating light. It is also desirable that the light 7, which is once inputted in the active material such as the Nd:YAG crystal 1, is not lost at the gap 3, and the light 7 crosses an oscillating light path 8 effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Minute Hand) The present invention relates to a semiconductor laser-excited solid-state laser containing a novel configuration.

(Prior art) In recent years, as the importance of solid-state lasers for optical processing applications has increased, and as short-wavelength semiconductor lasers such as those in the 0.81 μm band have become more powerful and less expensive, for example, neodymium-containing yttrium・Aluminum Carnet) (Nd:
There is a growing trend toward miniaturization and higher conversion efficiency by exciting YAG) with a semiconductor laser.

An example of the configuration of such a semiconductor laser-excited solid-state laser is schematically shown in FIG.

That is, the oscillation light 12 of the 0.81μn1 oscillation semiconductor laser 11 is transmitted through the lens 13 to the Nd:YAG crystal 14.
As a result, the light from 1% 14 is passed through the optical resonator 15 to obtain oscillated light 16 in the wavelength range of 1.06 μIII.

(Problems to be Solved by the Invention) However, in a solid-state laser with such an arrangement, a considerable portion of the excitation light is lost during condensation, and furthermore, ill light once absorbed by the neodymium ions is also incoherently left light. Significant loss due to radiation. For these reasons, there have been limits to the threshold and conversion efficiency of such solid-state lasers.

As is well known, the threshold value of laser oscillation is determined by optical gain and loss, and the differential quantum efficiency is determined by the utilization efficiency of supplied energy. In the conventional end-pump arrangement, the active material is excited in the length direction in order to effectively utilize the excitation light from the semiconductor laser, but this places a limit on the energy that can be input. Yes, a considerable portion of the input light is lost due to reflection etc. Also, because the sides are typically unprocessed, a significant portion of the input is lost to incoherent light emission. On the other hand, side pumping has the advantage of being able to use a large number of semiconductor lasers, but is disadvantageous because the distance to the direction of incidence is short. In the past, no attempt has been made to overcome this disadvantage by providing a reflective surface. For example, the magazine “Applied Φ Physics Letter (App
lied P-bysica Letters) J
, Vol. 28, No. 5 (September 1973), p. 235 Paper by L. B. Czesler, I), A. Draguerre 1. Magazine "Soviet Journal of Quantum Electronics"
al of Quantum Electronics
)J.

Vol. 11, No. 11 (November 1981), page 1471, V, 1. Paper 2 by Virak et al.

In many cases, commonly used light sources use incoherent light, and because the importance of the light confinement effect has not been recognized, sufficient effects have not been achieved.

In view of such circumstances, an object of the present invention is to provide a semiconductor laser pumped solid-state laser having a low threshold and high wavelength conversion efficiency.

(Means for Solving the Problems) The configuration of the present invention uses a columnar transparent solid material containing trivalent rare earth ions or lattice defects with laser action as an active substance and L7, and a plurality of semiconductor lasers as an excitation source. In a semiconductor laser-excited solid-state laser, a gap J″J1 on a side surface of the solid material allows all of the excitation light of the semiconductor laser to enter.
side portions of the solid material are covered with an antireflection film, reflective mirrors are provided on both end faces of the solid material that output the laser oscillation light, and the solid material has a cross section that effectively confines the excitation light in all two dimensions. Features.

(Function) According to the configuration of the present invention, when a laser beam is used for excitation, it is possible to achieve an almost complete confinement effect for the excitation light because the optical path of the incident light is small, and at the same time, it is possible to achieve an almost complete confinement effect for the excitation light. By not exerting a confinement effect on coherent light, the emitted light is effectively reabsorbed by rare earth ions (b) by lattice defects, thereby lengthening the excited state lifetime and producing the effect of lowering the oscillation threshold.

Magazine [Applied Physics Letters (Ap-pl
jed Physics T+etters) J
, Vol. 23, No. 4 (August 1973), p. 173, article 3 by Mita.

(Example) In order to further clarify the main features and advantages of the present invention, a detailed explanation will be given below with reference to the drawings.

FIG. 1 is a diagonal 5-level diagram schematically showing an embodiment of the present invention, and FIG. 2 is a sectional view thereof. Long columnar Nd:Y
Among the side surfaces of the AG crystal 1, there is an open space I! for the excitation light (not shown) of the plurality of semiconductor lasers 2 attached to the side surfaces to be incident thereon.
Only 1i3 is left and the remaining part is covered with a reflective coating 4. Both end faces of this Nd:YA(l crystal 1 form reflecting mirrors 5 to enable laser oscillation as is well known. In this case, in order to effectively utilize the laser excitation light, In order to avoid light loss, it is advantageous to confine the excitation light in a plane perpendicular to the oscillation light.Furthermore, as shown in FIG.
It is desired that the light 7 incident on the active material such as the crystal 1 is not lost through the gap 3 or the like, and moreover, it can effectively intersect with the oscillation optical path 8. The example 1-9 shown in this drawing is an example of the optical path 8 when the semiconductor laser 2 is attached by processing one corner of the cross-section of the active material having a substantially square shape to be slightly oblique.
shows.

In addition to the N(1: YAG crystal 1) mentioned in this example, active materials such as Nd-containing glass, other rare earth-containing transparent materials, or alkali halide crystals containing color centers 6 to 6 can also be used. , if a semiconductor laser corresponding to the excitation wavelength is available, it can be applied.

Solid state lasers of the present invention can utilize thinner active materials than conventional solid state lasers, allowing for higher excitation densities and lower thresholds. Furthermore, it becomes possible to use all materials having rare earth gold concentrations lower than those conventionally employed, thereby reducing the proportion of non-radiation due to the concentration quenching effect.

In addition to the case shown in this example [7], it is also possible to achieve a similar effect by placing the active material in a cavity with high reflectance, but in this case the excitation density will drop dramatically. The effect is diminished. It goes without saying that such an effect can be realized not only in an optical oscillator as in this embodiment, but also in an optical amplifier.

In order to realize an effective light confinement effect, it is necessary to have a high reflectance on one surface and a low void ratio.

The effect of light confinement depends on the spatial loss factor
It is given by the following equation.

f-ΣAi *'f'i / (4*V)...
...(1) Here, % A I + i' I is the area and transmittance of each part of the surface, and ■ is the volume (
(See paper 3).

In the case of normal light-emitting diode excitation, it is not easy to make h'k1cm' or less, but in the case of laser excitation, by reducing the void ratio, f(0,1(m') and the volume can be reduced. In order to fully exhibit this effect jIL, it is desirable to set f(0,3cIn').

(Effect of the invention) Illumination by the semiconductor laser-excited solid-state laser of the present invention.

High output, low threshold value, and compact size that were previously unobtainable.

A solid-state laser with high conversion efficiency can be realized.

The first reason for this improvement is the effective use of excitation energy, the second is the extension of the excited state lifetime, the third is the increase in excitation density due to miniaturization, and the fourth is the non-radiation due to the use of low concentration materials. This is due to a decrease in transitions.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a semiconductor laser pumped solid-state laser according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the active material in FIG. 1, and FIG. 3 is a schematic block diagram of a conventional semiconductor laser. It is. 1.14...Nd: YA () crystal, 2.1
1...Semiconductor laser, 3...Void, 4
...Anti-reflection film, 5...Reflector, 7.
...Incoming light, 8... Optical path of oscillation light, 12.
...Oscillation light, 13...Lens, 15. Old optical resonator, 16..Oscillation light. 19 = half ring 4 not one “′

Claims (1)

[Claims] In a semiconductor laser-excited solid-state laser in which a columnar transparent solid material containing rare earth trivalent ions or lattice defects having a laser action is used as an active substance and a plurality of semiconductor lasers are used as an excitation source, excitation of the semiconductor laser on a side surface of the solid material is performed. Side portions other than the void that allows light to enter are covered with an antireflection film, and reflecting mirrors are provided on both end faces of the solid material that output the laser oscillation light, so that the solid material effectively uses the excitation light in two dimensions. A semiconductor laser-excited solid-state laser characterized by having a confining cross section.