Swinging photorefractive optical spatial solitons

Summary form only given. Recently, incoherent-soliton-related phenomena, such as partially incoherent spatial solitons, modulation instability, and pattern formation in spatially incoherent light beams, have aroused many research interests in nonlinear optics. One thing in common of the these phenomena is that the material must be noninstantaneous, i.e., the material gives rise to the nonlinear refractive index depending on the optical intensity averaged over a period of time longer than the material response time. Biased photorefractive material can support optical spatial solitons. Due to its charge redistribution nature, photorefractive nonlinearity is of course noninstantaneous. To understand how a varying optical spatial soliton beam behave in such a noninstantaneous nonlinear medium, here we report the experimental observation of the dynamical evolution of the soliton beam. The observation is done when the soliton beam is launched into a biased SrBaNb/sub 2/O/sub 6/ photorefractive crystal.