Photoinduced absorption in photorefractive barium titanate

The photorefractive properties of barium titanate are influenced by the presence of secondary photorefractive centers. The consequence is an intensity-dependent photorefractive effort due to changes in the effective empty trap concentration. Information about these centers can be obtained by studying the photo-induced absorption. We have measured the spectral and temporal characteristics of the intensity-dependent absorption induced in barium titanate by illumination with argon laser light. The absorption spectrum consists of a fast (millisecond) and a slow (seconds) component, with absorption peaks in the visible and near infrared. We discuss possible sources for this absorption and the effects on the photorefractive properties.