Spatial solitons in photorefractive media.

We show that photorefractive media can support a new type of spatial soliton, in which the diffraction is balanced by the self-scattering (two-wave mixing) of the beam spatial frequency components. This photorefractive soliton possessses some unique properties, such as independence of the absolute light intensity, and can experience absorption (or gain) with no change in its transverse structure.