Process for preparing low-temperature phase barium metaborate monocrystalline film

Abstract

A method for preparing a low-temperature phase barium metaborate single crystal thin film, comprising the following specific steps: placing a Li2CO3 and Al2O3 mixed material block with pores in a platinum crucible; placing or suspending a double-sided polished α-BBO wafer on On the platinum wire, add a crucible cover covered with Li2CO3 and Al2O3 mixed powder and a thermocouple, seal the top of the crucible with a platinum cover, and place it in a resistance furnace; the resistance furnace is heated to 700-1000°C and kept at a constant temperature for 2-100 hours , Li2O diffuses into the α-BBO wafer, and undergoes a solid-state reaction with the α-BBO wafer, so that the surface layer of the α-BBO wafer undergoes a phase change to form a β-BBO single crystal thin film. The method can grow micron-scale β-BBO single crystal thin films meeting requirements on α-BBO substrates, not only saves materials, but also can be produced in batches, which is of great significance to the development of laser technology and integrated optics.

Description

technical field [0001] The invention relates to a preparation method of a low-temperature phase barium metaborate (β-BBO) single crystal thin film, in particular, a low temperature phase is prepared on a high temperature phase barium metaborate (α-BBO) single crystal substrate by adopting a gas phase transport equilibrium technology The method of barium metaborate single crystal thin film forms a β-BBO / α-BBO single crystal composite thin film material, and the material has a 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. α-BBO crystal has a center of symmetry and is a UV birefringent crystal with excellent performance, which can be grown by ordinary pulling method and crucible descending method (see Journal of Crystal Growth, Vol. 191, 1998, p. 517, and patent ZL9...

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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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