STABILITY OF THE ASYMMETRIC NONLINEAR MODE TRAPPED IN SYMMETRICAL PLANAR WAVE-GUIDES

We examine the reliability of the numerical approach on the study of the asymmetric nonlinear mode trapped in a thin linear film sandwiched in an infinite self focusing medium, and thus resolve a standing controversy on the stability of the mode trapped between the bifurcation point and the transition point on the dispersion curve reported in the literature. We also demonstrate that as a result of the instability there exists a class of quasi-periodic solutions arising from the instability development of the asymmetric mode on the unstable branch and weakly stable branch. In addition, the effect of loss on the propagation characteristics of the nonlinear mode is investigated. The evolution is shown to follow the dispersion curve adiabatically in the stable region provided the loss is small, whereas the initial excitation on the unstable branch leads to evolution wandering away from or oscillating around the dispersion curve.