Z-SCAN EXPERIMENTS WITH CUBIC PHOTOREFRACTIVE CRYSTAL BI12TIO20

We present original data on experiments with cubic photorefractive cry stal Bi12TiO20 under an external de electric field in the configuratio n of Z-scan characterization technique. In particular, behavior of the Z-scan curves versus the external dc field, light polarization, and t he (focused beam) /(uniform sample illumination) intensity ratio is re ported. The data obtained are interpreted in the framework of an origi nal theoretical analysis based on the standard drift model of the phot orefractive effect and assumption of a Gaussian profile of the propaga ting laser beam.