Abstract

Large high-quality crystals of barium titanate (BaTiO₃) and potassium niobate (KNbO₃) are routinely grown by the top-seeded solution growth method and are poled by straightforward techniques. However, optimization of their photoretractive properties is a more difficult problem, requiring a substantial effort in the theoretical understanding of the mechanisms of photorefractive behavior as well as the growth, processing, and characterization of crystals given a variety of treatments. In our experiments, we studied undoped, Mn-doped, and Fe-doped crystals of both materials. Their photorefractive properties—beam-coupling gain and response time—are clearly altered by doping and postgrowth oxidation-reduction treatments. Existing theoretical models are helpful in understanding the basis of this behavior but are not yet sufficient to explain completely the observed phenomena. We describe our progress toward solving these problems, including crystal growth procedures, postgrowth processing, characterization techniques, defect modeling, and other approaches to improve the photorefractive sensitivity, such as operation at high temperature.

© 1988 Optical Society of America