Process for preparing low-temperature phase barium metaborate monocrystalline film

Abstract

A process for preparing a low-temperature phase barium metaborate monocrystalline film comprises following particular steps: arranging Li2CO3 and Al2O3 mixed feed block with ari holes in a platinum crucible; arranging or hanging an alpha-BBO wafer with two face polished on a platinum thread, adding a crucible lid covered by Li2CO3 and Al2O3 mixed powder and thermocouple, sealing a top portion of the crucible by a platinum lid, and arranging the crucible in an electric resistance furnace; heating the electric resistance furnace to lift temperature to 700-1000 DEG C, holding the temperature for 2-100 hours, diffusing Li2 to the alpha-BBO wafer to perform a solid state reaction with the alpha-BBO wafer, so that a surface layer of the alpha-BBO wafer generates phase changes to generate a beta-BBO single crystal film. The invention can grow a micron level beta-BBO single crystal film which is accorded with request on a beta-BBO substrate, thereby only only materials can be saved, but also mass-production can be performed, the invention has important significance on development of laser technic and integrated optics.

Description

technical field [0001] The invention relates to a method for preparing a low-temperature phase barium metaborate (β-BBO) single crystal thin film. Specifically, a low-temperature phase is prepared on a high-temperature phase barium metaborate (α-BBO) single crystal substrate by using gas phase transport equilibrium technology. The method of barium metaborate single crystal thin film forms β-BBO / α-BBO single crystal composite thin film material, and this material has very wide application prospect. Background technique [0002] Barium metaborate BaB 2 o 4 (hereinafter referred to as BBO) has two phases, a high temperature phase (α phase) and a low temperature phase (β phase), and its phase transition temperature is 925°C. The α-BBO crystal has a center of symmetry and is a UV birefringent crystal with excellent performance. It can be grown by ordinary pulling method and crucible drop method (see Journal of Crystal Growth, volume 191, 1998, page 517, and patent ZL97106378 ....

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Problems solved by technology

[0005] (1) The growth rate is slow and the growth cycle is long, and the growth cycle of a single crystal is as long as 1 to 3 months;

[0006] (2) These technologies can be used to obtain larger bulk single crystals, but with the development of laser technology towards integration and miniaturization, especially in the field of femtosecond laser technology, in order to overcome the fundamental frequency light and The problem of group velocity mismatch between frequency doubling lights often requires thinner β-BBO crystals as frequency doubling devices (see Acta Optics Sinica, Vol. 15, 1995, p. 641), while β-BBO crystals are softer, The mechanical strength is low, and there are problems such as easy cracking and deformation during processing, especially in the process of processing thinner parts (see Optical Technology, 1998, No. 4, p. 39), if the prior technology will be used It is very difficult to process the grown β-BBO crystals into micron-scale or even thinner wafers, and it will also cause a great waste of materials. At the same time, the growth efficiency is low, which is far from meeting the needs of the rapidly developing laser technology.

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