Optical second order nonlinearity of transparent Ba2TiGe2O8 crystallized glasses

Optical second-order nonlinearity of ferroelastic Ba2TiGe2O8 crystal in transparent crystallized glasses was estimated by means of the Maker fringe technique. Transparent crystallized glasses were fabricated by crystallization of a glass with the composition of 30 BaO.15 TiO2.55 GeO2. The crystalline layer consisting of highly oriented Ba2TiGe2O8 crystals was formed at the surface of about 9 μm thickness, and a clear second-harmonic generation was observed. The optical second-order nonlinearity of d33 for Ba2TiGe2O8 crystal was found to be ∼10 pm/V, being comparable to d22 and d31 of LiNbO3, and demonstrating that Ba2TiGe2O8 crystal is an excellent candidate for nonlinear optical crystals.