Electrophotochromic gratings in photorefractive Bi(12)TiO(20) crystals

We present the first experimental demonstration of quasi-permanent holographic recordings in Bi(12)TiO(20) crystals through what is to our knowledge a new electrophotochromic effect. This arises from spatial redistribution of some centers that are different from photorefractive centers. Light diffracted from this photochromic grating records a secondary photorefractive hologram. Interaction between both gratings results in asymmetric polarization properties and reversible electric field enhancement of diffracted beams.