Light propagation in a directional coupler with saturable nonlinearity

The propagation of laser radiation in a nonlinear directional coupler with identical optical waveguides is studied theoretically. Account is taken of refractive index saturation. Bifurcations of the intensity distribution and transmission characteristic are revealed, and respective regions in the parameter plane are delineated. Two points of input intensity self-switching are found. A coupling length vs. normalized input intensity is investigated for different values of the nonlinearity parameter. Distinctive features of the coupler with saturated nonlinearity compared with Kerr-type couplers are highlighted.