Beam propagation method analysis of transverse-electric waves propagating in a nonlinear tapered planar waveguide

The propagation of TE-polarized guided waves in a nonlinear tapered waveguide is studied. The incident fields are chosen from the stable branches of the nonlinear dispersion curve in its uniform section. The propagations of the field in both directions are calculated by the beam-propagation method. Wave propagation in the tapered waveguide is discussed in terms of the nonlinear dispersion curves of the waveguide. Depending on the intensity, the field can radiate as a spatial soliton or it can have an abrupt transition between the guided mode and the surface polariton. The wave propagation of an incident field that is composed of a dominant TE0 wave and a small TE1 wave is investigated. Finally, using a property of this wave propagation, we present a new device for continuous signal routing.