CS223542B1 - Method of selection of medium for temperation of monocrystals of the yttrite-aluminate garnet - Google Patents

Abstract

Method of environment selection for tempering single crystals of yttrite-aluminum garnet, enabling analytically difficult to detect particular admixtures minimum wavelength absorption coefficient from 500 to 2600 nm where they emit light lasers using laser bars from a single crystal yttritium aluminum garnet, activated by rare earth ions get high quality active laser material which is achieved by having the given the single crystal, the dependence of the absorption is determined the coefficient at the wavelength of 300 to 500 nm after heating in the atmosphere, once containing 10 to 100 vol% oxygen, once 10 to 100% by volume of hydrogen and if curves dependence of absorption coefficients intersect each other in the 300 to 500 nm range it is chosen for the final tempering of the single crystal free oxygen-containing environment otherwise, a free environment hydrogen.

Description

(54) Method for selecting the environment for tempering yttrium-aluminum garnet single crystals

A method for selecting the environment for tempering yttrium-aluminum garnet monocrystals, which enables to obtain a minimum absorption coefficient at 500 to 2600 nm wavelength, where light emitting lasers using rare-earth activated yttrium-aluminum garnet monocrystals, emit light, high quality active laser material, which is achieved by detecting the dependence of the absorption coefficient on the wavelength 300-500 nm after heating in an atmosphere, once containing 10-100 vol% oxygen, once 10-100 vol% hydrogen, for a single crystal and if the absorption coefficient curves in the region of 300-500 nm intersect each other, a free oxygen-containing environment is chosen for the final single-temperature tempering, otherwise the free hydrogen-containing environment.

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The invention relates to a method for selecting an environment for tempering yttrium-aluminum garnet monocrystals to be used as an optical component for the visible and / or near infrared region.

Yttrium aluminum garnet monocrystals find a wide range of applications as laser active materials and as special scintillators. In both cases, the efficiency of the whole device, assembled using optical components of yttrium aluminum garnet single crystals, is decisively influenced by the actual absorption of the material at the working wavelength. This is particularly important in the case of yttrium-aluminum grenade lasers containing rare earth ions as activators, since photons, depending on the reflectance of the output mirror, pass through the active material several times. Therefore, a quality active material for / lasers should not have an absorption coefficient for emitted light higher than one thousandth of a cm. Such a low absorption is usually difficult to measure because the reflectivity of the measured sample also applies. Furthermore, this absorption is also affected by chance

- 2 223 542 the presence of very small, analytically difficult to determine general elements, and varies depending on the species and the concentration of the direct elements depending on the «

for processing single crystals tempering. Therefore, even knowing the dependence of this absorption on the type of environment during tempering and admixture content, the choice of the optimum environment is not easy and tempered single crystals, which are further mechanically worked into the final product do not always have the least possible absorption.

This deficiency can be overcome by the method of temperature control of the yttrium aluminum garnet single crystals according to the invention, which is characterized in that the single crystal is found to be dependent on absorption wavelength in the range 300-500 nm after heating in an atmosphere containing 10-100 % oxygen at temperatures of 1100 to 1800 ° C and in an atmosphere containing 10 to 100% hydrogen, and if the absorption coefficient curves intersect in the range of 300 to 500 nm, an environment containing free oxygen is chosen for the final tempering of the single crystal. otherwise, the medium containing free hydrogen.

In this way, a tempering environment is chosen which guarantees a minimum absorption coefficient at a wavelength of 500 to 2600 nm for a given content and type of admixtures at a wavelength of 500 to 2600 nm, emitting light using lasers using rare earth ions activated yttrium aluminum garnet single crystal. Thus, the optimum tempering environment can be selected easily and unambiguously by the method of the invention and thus provide the highest possible optical quality of the yttrium aluminum garnet single crystal products.

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Example 1

Yttrium aluminum garnet single crystal activated with 0.6% by weight of neodymium ions was grown by the Czochralski method from a melt prepared from raw materials with a purity of 99%.

Two plates with a thickness of 2 · mm were made from the embryo. One was tempered in pure oxygen, the other in hydrogen at 1600 ° C for 1 hour. After polishing the surfaces of the plates, the optical transmittance-wavelength curves in the region of 300-500 nm were found on the spectrography, and it was found that the curves did not intersect in that region. Therefore, the single crystal was tempered in hydrogen at 1600 ° C for 6 hours and after tempering was processed into laser bars with a diameter of 6 mm and a length of 60 mm. The output energy at pumping 50 J was 600 + 30 mJ, while for one rod prepared from the same single crystal and tempered under the same conditions but in oxygen, it produced only 400 J output energy at pumping at 50 J

Example 2

The yttrium aluminum garnet single crystal with an admixture of 0.6% by weight of neodymium ions of unspecified purity was cut into semiproducts (prisms) for the manufacture of laser bars of 5 mm diameter and 60 mm length. Two 2 mm plates were made from the residues. One plate was tempered at 1350 ° C for 8 hours in air, the other at 1800 ° C for 45 min in an atmosphere of 25 vol% hydrogen and 75 vol% nitrogen. After polishing the surfaces of the plates, a spectrophotometer was used to measure the optical transmittance versus a wavelength in the range of 300 to 500 nm, and

4,223,542 that the respective curves intersect at a wavelength of 395 nm. Therefore, the blanks were allowed to air at 1400 ° C for 15 hours.

They were then processed into laser bars which, in continuous laser operation, exhibited a power output of 40 IW when using an output mirror with a reflectivity of 95% and at 3 kW. One of the laser bars, which was prepared from a hydrogen tempered blank at 1700 ° C for 3 hours, yielded only 30 W at a pumping of 3 kW. cm in the second case 0.005 cm ^-1 .

Claims (1)

THE INVENTION Method for selecting the medium for tempering the yttrium-aluminum garnet single crystals, characterized in that the absorption coefficient is determined for a given wavelength in the region of 300-500 nm after heating in an atmosphere containing both 10 to 100 vol% oxygen and 10 to 100 vol%. % hydrogen at 1100 to 1800 ° C and if the absorption coefficient dependency curves intersect, a free oxygen-containing environment is chosen for the ultimate temperature of the monocrystals, otherwise the free hydrogen-containing environment ·