NaCaBe2B2O6 nonlinear optical crystal, its growth method and application thereof

Abstract

A NaCaBe2B2O6 nonlinear optical crystal is prepared by a molten salt growth method as follows: uniformly mixing NaCaBe2B2O6 and a fluxing agent in proportion, heating to 800 DEG C, cooling to 2-10 DEG C higher than saturation temperature after reaching constant temperature so as to obtain a high-temperature solution; putting seed crystal on a seed rod into the high-temperature solution, rotating the seed rod, cooling to the saturation temperature, slowly cooling, lifting the obtained crystal out of the liquid level and cooling to room temperature so as to obtain the NaCaBe2B2O6 nonlinear optical crystal. The NaCaBe2B2O6 nonlinear optical crystal has a nonlinear optical effect and wide light transmission band. Ultraviolet cutoff edge reaches 190 nm. The crystal doesn't resolve in water, has good chemical stability, is suitable for laser frequency conversion requirements of ultraviolet band, can be used to manufacture nonlinear optical devices and harmonic light output devices for realizing 2 octaves, 3 octaves, 4 octaves, 5 octaves or 6 octaves of Nd:YAG laser, and also can be used in harmonic light output devices of other laser wavelength to generate coherent light with its wavelength being equal to or less than 266nm for output.

Description

technical field [0001] The present invention relates to a kind of optoelectronic functional material and its growth method and application, especially to a kind of nonlinear optical material and its preparation method and application, specifically, to a calcium sodium fluoroboryryllate (NaCaBe 2 B 2 o 6 F) Nonlinear optical crystals and their growth methods and applications. The calcium sodium fluoroborate beryllium (NaCaBe 2 B 2 o 6 F) NCBBF for short. Background technique [0002] The nonlinear optical effect of crystal refers to such an effect: when a laser beam with a certain polarization direction and a certain incident direction passes through a nonlinear optical crystal (such as NCBBF), the frequency of the laser beam will change. figure 1 with figure 2 A typical schematic diagram of this effect. [0003] Crystals with nonlinear optical effects are called nonlinear optical crystals. Here nonlinear optical effects refer to effects such as frequency doubling, ...

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Problems solved by technology

However, the effective frequency-doubling output wavelengths of these three crystals are limited in the ultraviolet spectral region.

For BBO it is due to (1)(B 3 o 6 ) group has a large conjugated π orbital characteristic, which red-shifts the band gap of the group, which leads to the absorption edge of the BBO crystal at 189nm; (2) limited by the ultraviolet absorption edge, the crystal cannot produce Harmonic light; (3) planar (B 3 o 6 ) group leads to the birefringence Δn≈0.12 of the BBO crystal, and the large birefringence makes the acceptance angle of the BBO crystal at the quadruple frequency Δθ=0.45mrad*cm, which is too small for practical devices

For LBO, because the birefringence is too small, phase matching cannot be achieved in a shorter wavelength band, so effective frequency-doubling optical output cannot be produced.

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