Abstract
A method of examining the photorefractive grating in a self-pumping barium titanate crystal is described; in this method, photorefractive grating elements are sequentially erased using a fine pulsed beam of photocarrier-generating light, while the resulting decrements in the phase-conjugate output are recorded. The erase beam scans the crystal in raster fashion, producing a map of decrements in the phase-conjugate output; these are interpreted as indicating the position of volume photorefractive grating elements that contribute to the phase-conjugate output. The results show that important elements of grating structure do exist in the front region of the crystal where the pumping beam enters.