INVESTIGATION OF STOCHASTIC PHOTOREFRACTIVE BACKSCATTERING

It is shown that, in photorefractive crystals with a dominating local nonlinear response, small temporal fluctuations of the space-charge fi eld can induce strong noisy (stochastic) backscattering. For sufficien tly large interaction lengths a small nonlocal component of the photor efractive response can suppress the fluctuation of the scattered-light intensity and can result in nearly complete and regular nonlinear ref lection. Stochastic stimulated backscattering is detected and investig ated in LiNbO3:Fe crystals. The scattering manifests itself in the opt ical configuration, where noiseless spatial amplification of backward waves is impossible, The main characteristics of the observed backscat tering are in good qualitative agreement with the calculated ones. (C) 1996 Optical Society of America.