Gray spatial solitons in biased photorefractive media

We provide a detailed analysis of gray spatial optical solitons in biased p hotorefractive media. The properties associated with these solitons, such a s their transverse velocity, spatial width, and phase profile, are obtained as functions of their normalized intensity and degree of "grayness." By em ploying the stability criterion based on the renormalized field momentum, w e investigate the stability regions of gray spatial photorefractive soliton s. The process of the soliton Y splitting arising from an initially even fi eld depression is quasi-analytically described by use of a Hamiltonian form alism. (C) 2001 Optical Society of America.