Waveguides induced by photorefractive screening solitons

Summary form only given. Photorefractive spatial solitons form when the optically induced space-charge field modifies the refractive index via electro-optic effect and forms a waveguide that confines the optical beam that has induced the waveguide. Since the photorefractive response is wavelength dependent, one can generate a soliton with a weak beam and guide in it a more intense beam of a less photosensitive wavelength. Here we present theoretical and experimental studies of the waveguides induced by photorefractive screening solitons. We show that the number of guided modes in a waveguide induced by a bright screening soliton increases monotonically with increasing intensity ratio (the ratio between the peak soliton intensity and the background or dark irradiance), whereas the waveguides induced by dark screening solitons are always single-mode waveguides.