Propagating Modes in Optical Waveguides Terminated by Perfectly Matched Layers

Abstract — For numerical simulations of optical waveguides, perfectly matched layers (PMLs) are widely used to truncate the unbounded transverse directions. However, a PML induces some undesired side-effects to the propagating modes in the waveguide. In general, the propagation constant becomes complex, so that the mode may grow or decay exponentially along the waveguide axis. Through a perturbation analysis, we obtain approximate formulas for the propagation constants of PML-terminated planar waveguides. Index Terms — Optical waveguides, propagating modes, perfectly matched layers, perturbation methods