Spatial Solitons in Optically-Induced Gratings

We study experimentally nonlinear localization effects in optically-induced gratings created by interfering plane waves in a photorefractive crystal. We demonstrate the generation of spatial bright solitons similar to those observed in arrays of coupled optical waveguides. We also create pairs of out-of-phase solitons which resemble ``twisted’’ localized states in nonlinear lattices.