Nonlinear correction of a light beam shape in photorefractive optical waveguides

The self-actions of light in photorefractive media result in the phenomena of nonlinear optical surface waves and spatial solitons, effects of beam self-focusing and self defocusing. They can be realized here at optical powers some orders less than in Kerr media. Optical waveguides suggest in such a way additional advantages with respect to 3D media. It is due to the possible enhancement of their photorefractive properties by surface doping, with using different dopants for separate areas of the same sample, and larger light intensity within waveguides. In this work the changes of light beam shapes via spatial self-actions in lithium niobate optical waveguides doped by Fe are experimentally investigated and discussed.