Self-trapped bidirectional waveguides in a saturable photorefractive medium

A theory of self-trapped bidirectional waveguides was developed. In counterpropagating (CP) geometry, the inclusion of time-dependent effects was found to be crucial for the formation of dynamical waveguiding structures. The generation of a CP (1+1) vector soliton was demonstrated numerically, and a more general class of nonsoliton steady-state solutions proposed. The level of temporal coherence of interacting beams influenced the mutual coupling due to the formation of a refractive index grating. In addition to the generation of steady-state induced waveguides, the dynamic alternation of states followed by a transverse modulational instability, as well as the onset of longitudinal modulational instabilities were observed.