Temporal evolution of beam fanning in LiNbO(3):Fe, In crystals.

We investigated the temporal evolution of light-induced scattering in LiNbO(3):Fe, In crystals with different doping concentrations. A special behavior of the beam fanning was found when the intensity of the incident light was relatively weak. In this case the beam fanning became stronger at the beginning of the illumination and then was greatly reduced, which was observed only at strong incident light intensities. This phenomenon was analyzed on the basis of the saturation space-charge field. The intensity threshold effect and the concentration threshold effect were successfully explained.