Gray spatial solitons in biased photorefractive media

Summary form only given. Recently, soliton splitting has been successfully used to write permanent Y-waveguide structures (3-dB splitters) in the bulk of a photorefractive crystal. Such Y-junctions can then be employed to guide other intense beams at less photosensitive wavelengths (/spl sim/1.5 /spl mu/m) or can be permanently impressed (fixed) into the crystalline lattice. An investigation of the properties of these Y-junction waveguides requires an in-depth understanding of the underlying soliton Y-splitting process. During this process two gray photorefractive solitons are emitted in opposite transverse directions so as to conserve the overall linear momentum of the system. In what follows we provide a detailed analysis of the properties of gray photorefractive solitons involved in this Y-junction formation.