Grating erasure in the dark has different temporal characteristics for different crystals. We present experimental results of four-wave mixing in a BaTiO<sub>3</sub> crystal, which exhibits a large increase in the diffraction efficiency for the first few seconds after the writing beams are switched off. It is clear from these results that multiple photorefractive processes that have different time constants are involved. We study two different models, including two types of charge recombination center, one with a smaller and the other with larger time constant. The rising phenomenon is explained by use of one of these models. Experimental results for three crystals that exhibit different temporal behaviors are shown, and properties of these three crystals are discussed based on calculations for this model.
© 2000 Optical Society of America
(160.5320) Materials : Photorefractive materials
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(190.5040) Nonlinear optics : Phase conjugation
(190.5330) Nonlinear optics : Photorefractive optics
Imtiaz Ahmad Taj, Ping Xie, and Teruhito Mishima, "Anomalous temporal behavior of photorefractive wave mixing owing to the existence of both positive and negative charge carriers," J. Opt. Soc. Am. B 17, 1740-1748 (2000)