Solitary Wave Emission in a Planar Waveguide with the Adjoining Linear and Nonlinear Thin Film

The spatial soliton in Kerr-like nonlinear media has been the subject of extensive research because of its potential application to all-optical switching [1]. In particular, spatial solitary waves in nonlinear waveguides are of cunent interest because of a novel, very interesting optical bistable and switching effect [2,3]. The soliton coupler, suggested by Heartley et al., is one of the most exciting examples to utilize the threshold effect of spatial soliton emission for the sharp switching devices [4]. The majority of theoretical work to date, however, has been restricted to the planar waveguides consisting of the linear thin film bounded by one or two nonlinear semi-infinite media [2,3]. In this work, we consider a planar waveguide consisting of the adjoining linear and nonlinear guiding thin film covered by two linear semi-infinite media, as shown in Fig. 1. The waveguide configuration has distinctive features: (i) due to the confinement of the nonlinearity, the emitted nonlinear wave is generally a solitary wave rather than a soliton and (ii) it can control the emitted power of the solitary wave and the hysteresis of the optical bistability by varying the thickness of the nonlinear thin film.