Abstract

An intensity-dependent absorption in photorefractive barium titanate has recently been reported. This effect results in nonsymmetric behavior of the two-beam coupling gain coefficient. Various characteristics of the intensity-dependent absorption coefficient have been measured. These include temperature dependence and temporal behavior. To date there has been no theoretical treatment of these phenomena. This paper discusses the intensity-dependent absorption via a model in which the absorption is accounted for by the existence of shallow traps. These traps, which are unoccupied at room temperature, become filled by free charge carriers generated by the interaction of the laser light with deep trap impurities that are also present. The rate equations for these interactions are presented and solved. The results are compared with and shown to be in good agreement with experimental results.

© 1987 Optical Society of America