STOCHASTIC PHOTOREFRACTIVE BACKSCATTERING FROM LINBO3 CRYSTALS

Our experiment shows that stimulated backscattering from photorefracti ve LiNbO3:Fe crystals occurs not only fur an orientation of the polar axis that is parallel to the input beam hut also For the opposite orie ntation, in which the spatial amplification of seed scattering through pi/2-shifted gratings is impossible. In the latter case scattering ex hibits pronounced noise properties. We show analytically and numerical ly that the observed regularities are explained by a model including a source of low-frequency temporal noise for the space-charge field and a strong photovoltaic effect. (C) 1996 Optical Society of America