Micro-architecture of nonlinear optical Ba2TiGe2O8 crystal dots and lines on the surface of laser-induced crystallized glasses by chemical etching

A combination technique of Nd:YAG laser (wavelength 1064 nm) irradiations and chemical etchings is applied to fabricate micro-architectures of nonlinear optical Ba2TiGe2O8 crystal dots and lines on the glass surface, and chemical etching behaviors are examined from confocal scanning laser microscope observations. Continuous wave Nd:YAG lasers with a power of 0.85 W and a scanning speed of 10 μm/s are irradiated onto the surface of CuO (1 mol)-doped 33.3BaO-16.7TiO2-50GeO2 glass and the crystallization of Ba2TiGe2O8 is induced. The chemical etching rates for crystallized dots and lines in a nitric acid solution (1N HNO3) are smaller than those for the precursor glass (non-irradiated part), and consequently, the micro-architecture of crystal dot arrays and patterned lines is fabricated. It is clarified that the post-annealing at near the glass transition temperature for the laser-irradiated samples is effective in eliminating selective rapid chemical etchings of the surrounding of crystal dots and lines. This study proposes that the patterning of optical functional crystals is possible on the glass surface by using the present technique.