Grating Decay in Reduced Barium Titanate Crystals

Abstract

Under inhomogeneous illumination, a refractive index grating will form in a barium titanate crystal through the photorefractive effect. Due to its large electro-optic coefficients and self-pumped phase conjugation, a photorefractive barium titanate crystal is of a special interest for many applications such as optical signal processing, optical phase conjugation and optical information storage. In general, the grating stored in a barium titanate crystal will fade in the dark soon. That is a barrier for the applications of optical information storage. Here we made a series of reduced BaTiO3 crystals and investigated the optical absorption, the dark decay and the light-induced decay. We found that the decay time of the grating can be lengthened by the reduction treatment. The grating can be kept in the crystal reduced around compensation point for more than a month. At high intensity, the speed of writing/erasing a grating can be determined by the optical absorption.