Pseudospectral Modal Method for Computing Optical Waveguide Modes

For optical waveguides with high index-contrast and sharp corners, it is challenging to develop efficient, accurate and general full-vectorial mode solvers. The classical mode-matching method is capable of computing modes to high accuracy for waveguides with right-angle corners, but it is not convenient to implement when the waveguide has lossy components. Numerical variants of the mode-matching method, such as the Fourier modal method (as a mode solver), are simpler to implement. In this paper, a recently developed pseudospectral modal method for diffraction gratings is reformulated as a full-vectorial waveguide mode solver. As demonstrated in a number of examples, the method can be used to calculate waveguide modes to high accuracy, and it is relatively simple to implement.