Vectorial simulation and power-parameter characterization of nonlinear planar optical waveguides

Abstract

The accurate modeling of nonlinear planar waveguides is surprisingly difficult. The modal field in the presence of strong nonlinear action has two-dimensional confinement, whereas the modal field associated with weak nonlinear effects can have either one- or two-dimensional confinement. For nonlinear planar optical waveguides possessing switching and/or bistability features, difficulties arise in predicting the correct threshold power. We present the full vectorial simulation of nonlinear planar waveguides, using two transverse spatial variables, together with the scalar model, using one transverse spatial variable, for comparison. How to characterize these planar structures, whether in terms of the total guided power or in terms of the power per unit length as a parameter, is discussed in detail. The computed results indicate that care must be exercised in making use of these nonlinear structures in practical systems. Several precautionary factors in the numerical simulation are exposed.