JPH05175591A - Laminated yag slab laser element and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide manufacture of a YAG which has the same characteristics as a single crystal, as well as to eliminate defects of requiring long time and having low yield in manufacturing a single crystal YAG laser element. CONSTITUTION:A single crystal YAG composed of yttrium, aluminum, and garnet, and a polycrystal YAG ceramics are laminated. The single crystal and the polycrystal are jointed at a temperature of 1400 deg.C or above. When the polycrystal ceramics is coupled with the single crystal, the grain boundary between the single crystal and the polycrystal begins to move toward the side of polycrystal, as a coupling temperature rises up. Finally, the grain boundary disappears and the whole becomes substantially a single crystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of so-called YAG elements made of yttrium, aluminum and garnet used as solid-state laser materials.

[0002]

2. Description of the Related Art A YAG single crystal as a solid-state laser material is manufactured by the Czochralski method, the Bridgman-Stockburger method or the like by adding Nd ³⁺ as an ion involved in light emission.

Further, the improved method is disclosed in JP-A-63-35490, JP-A-63-35496, JP-B-1-43719 and the like.

However, when a YAG single crystal is manufactured by this conventional method, the growth temperature is about 200.
0 ° C is required, and the growth rate is 0.2 to 0.3 m
Very slow at m / hr. Therefore, it takes about one month to produce one single crystal, and since the produced YAG single crystal does not have a uniform Nd element distribution state, only a part of it can be used and the yield is low. There is a drawback.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to manufacture a single crystal YAG laser device in a time-consuming manner.
It is another object of the present invention to provide a method for manufacturing YAG which has characteristics equivalent to those of a single crystal body while solving the drawback of low manufacturing yield.

[0006]

The present invention has achieved its object by laminating and joining a conventionally produced YAG single crystal and polycrystal.

In the production, first, Y ₂ O ₃ and A
A predetermined amount of 1 ₂ O ₃ is mixed, or a composite powder which is a compositionally uniform wet synthetic powder is formed beforehand by an alkoxide method, a coprecipitation method, or the like and then sintered. Sintering is vacuum sintering, HP
Although various methods such as (hot pressing) and HIP (hot isostatic pressing) may be used, in order to make the particles of the sintered body compositionally and structurally uniform and as fine and dense as possible, It is desirable to adopt a method such as HIP firing. The sintered body and the single crystal are joined together. As a joining method, a single crystal having an arbitrary crystal orientation is preferably brought into contact with sintered (100), (110) and (111) faces having a small surface energy and sintered polycrystalline YAG ceramics, and external pressure is applied if necessary. The temperature is raised to 1400 ° C. or higher, and bonding is performed by mutual diffusion.

In this bonding, no impurity component is added to the bonding interface, a rare earth element such as Nd, Ho or Er, which is involved in light emission, is added, Si containing no d-electrons other than components related to light emission, Means such as adding an element such as Mg can be adopted.

Here, in the polycrystalline ceramics bonded to the single crystal, the density of the sintered body is 98% of the theoretical density, preferably 99.5% or more, regardless of the presence or absence of single crystallization after the bonding. Is desirable in the sense of eliminating residual pores that cause optical scattering.

Here, when the joining temperature is low, the polycrystalline ceramics to be joined with the single crystal are only joined at the contact portion and the single crystallization process is not performed. Therefore, the translucent polycrystalline YAG is used. It is necessary to use ceramics.

[0011]

[Operation] When joining the polycrystalline ceramics to the single crystal, when the joining temperature becomes high, the grain boundaries between the single crystal and the polycrystals start to move toward the polycrystalline ceramics side, and finally the grain boundaries disappear. The whole becomes almost a single crystal. At this time, single crystallization can be achieved by introducing sufficient temperature and time without adding impurities other than the base material. At the time of bonding, addition of Si or Mg element to the bonding surface is for promoting the moving speed of grain boundaries to achieve single crystallization at low temperature and in a short time, but Cr and Ti are excluded. Addition of an element containing an electron significantly reduces the function as a laser material. In addition, the above-mentioned Nd, Ho and Er
An element such as a rare earth element that participates in light emission includes a d electron, but is an element for laser oscillation,
Not only can it be added, but it is also important in terms of increasing the laser power. These elements are uniformly dispersed in the ceramic along with the movement of the grain boundaries of the polycrystalline ceramic. Further, the single crystal also diffuses from the boundary portion as the polycrystalline ceramic and becomes relatively uniformly distributed.

[0012]

EXAMPLES Example 1 FIG. 1 shows a first example of joining single crystal and polycrystalline YAG ceramics, and shows an example in which no intervening material is present at the interface between the two joining materials.

In the figure, the YAG single crystal 1 having a thickness of 5 mm obtained by the Czochralski method and the transparency having a thickness of 2.5 mm, which is thinner than this single crystal, are excellent and Nd ₂ O ₃ is 1.0.
Polycrystalline YA containing by weight and obtained by vacuum sintering method
The surface roughness of each bonding interface of the G ceramics 2 is 0.1 μm or less by chemical polishing or mechanical polishing,
If possible, finish to 0.03 micron or less, sandwich the single crystal 1 between the polycrystals 2 on the joint surface,
Apply a load of ~ 300 g / cm ^{2 and} perform 17 in a hydrogen atmosphere.
Heated at a temperature of 00 ° C.

As a result, a slab laser element was obtained in which the concentration of Nd, which is a luminescent ion, was low in the central portion of the wall thickness and large in the outer peripheral portion. Taking the difference in Nd concentration in the plate thickness direction results in a slab laser having good heat dissipation because heat generation in the central portion is relatively small.

Example 2 FIG. 2 shows an example in which SiO ₂ as a grain boundary migration accelerating agent of a polycrystalline material was charged into the bonding interface to make the whole into a single crystal.

In FIG. 2, Si alkoxide was placed on the bonding interface on each bonding surface of a 4 mm thick YAG ceramic having a thickness larger than that of a single crystal in which Nd was dissolved.
175 in a hydrogen atmosphere under the same pressure as in Example 1.
The boundary surface 3 was moved by heating at 0 ° C. for 20 hours and sufficiently annealed to obtain a single crystal body.

Since this slab laser is annealed at a relatively high temperature, it has a small Nd concentration distribution and has characteristics substantially equivalent to those of a slab laser produced by a normal single crystal growing technique. Since only a part of the single crystal body is used, it has mass productivity and is advantageous in cost.

[0018]

According to the present invention, the following effects can be obtained.

(1) A laser element having excellent characteristics can be obtained by simply joining a single crystal and a polycrystal, in either case of single crystal formation or non-single crystal formation.

(2) In either case of single crystallization or non-single crystallization, the manufacturing surface can be shortened as compared with the conventional device manufacturing.

(3) The site condition (the conventional condition that there is no earthquake, lightning, etc.) can be eliminated, and a large amount of bonding and single crystallization can be performed in an electric furnace or the like, so that mass production is possible.

(4) Since the polycrystal can be made to have a higher concentration of luminescent ions than that produced by a normal single crystal growing technique, it is possible to produce a laser having a high output.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, showing a structure of a laser element in which a single crystal and a polycrystal are bonded together.

FIG. 2 is a diagram showing a second embodiment of the present invention, showing a process in which a single crystal and a polycrystal are bonded and a single crystal is formed by moving an interface.

[Explanation of symbols]

 1 Single crystal 2 Polycrystalline ceramics 3 Interface

Claims (2)

[Claims] 1. A stacked YAG slab laser device in which a single crystal YAG made of yttrium, aluminum and garnet and a polycrystalline YAG ceramic are stacked. 2. A method of manufacturing a slab laser element, in which a single crystal made of yttrium, aluminum and garnet and the same polycrystal are bonded at a temperature of 1400 ° C. or higher.