Abstract

We recently reported experiments demonstrating the existence of shallow traps in photorefractive barium titanate,¹ These traps can be populated by light and depopulated by thermal excitation in the dark. Once populated, the shallow traps cause partial decay of a photorefractive grating In the dark with a decay time of ~2–3 s as shown In Fig. 1. This coasting causes the grating erasure efficiency of a train of short (~20-ns) light pulses to vary with the repetition rate of the pulses.¹ Also, populating the shallow traps alters the absorption of the barium titanate crystal,² so long as the optical excitation cross sections are different for the deep and shallow traps.

© 1988 Optical Society of America