Determination of the physical parameters controlling the photorefractive effect in KTa_1−xNbxO_3:Cu,V

We report photorefractive, absorption, and photoconductivity measurements made on a KTa1−xNbxO3:Cu,V sample after a series of reduction and oxidation treatments. All relevant physical parameters that enter into the Kukhtarev model of the photorefractive effect are determined. Photorefractive measurements are compared with those expected from theory. The oxidation–reduction process is modeled, which permits us to determine the heat treatment that is necessary to produce a given index change and response time. We discuss approaches to optimization of the photorefractive sensitivity.