WAVE-GUIDES FORMED BY QUASI-STEADY-STATE PHOTOREFRACTIVE SPATIAL SOLITONS

We show that a quasi-steady-state photorefractive spatial soliton form s a waveguide structure in the bulk of a photorefractive material. Alt hough the optically induced waveguide is formed by a very low-power (m icrowatts) soliton beam, it can guide a powerful (watt) beam of a long er wavelength at which the medium is nonphotosensitive. Furthermore, t he waveguide survives, either in the dark or when guiding the longer-w avelength beam, for a long time after the soliton beam is turned off. We take advantage of the solitons' property of evolution from a relati vely broad input beam into a narrow channel and show that the soliton induces a tapered waveguide (an optical funnel) that improves the coup ling efficiency of light into the waveguiding structure. (C) 1995 Opti cal Society of America