Electrooptic and photorefractive properties of ferroelectric barium-calcium titanate crystals

Abstract

Barium-calcium titanate of congruently melting composition Ba0.77Ca0.23TiO3 is a novel photorefractive crystal. The refractive, electrooptic and photorefractive properties of an undoped as grown sample are investigated: The refractive indices are slightly smaller than those of BaTiO3, but the electrooptic coefficients r(113) = 36 /- 3 pm V-1 and r(333) = 140 /- 5 pm V-1 (light wavelength 514.5 nm) are larger. Light-induced absorption and a sublinear photoconductivity indicate the participation of a shallow level in the charge transport. There are no space charge limiting effects; bulk photovoltaic fields of the order of 15 kV m(-1) are present. The obtained two-beam coupling gain coefficients for ordinarily and extraordinarily polarized light are 160 m(-1) and 425 m(-1), respectively. In summary, barium-calcium titanate is a very promising crystal which will compete with barium titanate.