Alternatives to the Perfectly Matched Layer for Waveguide Simulation Using the FDFD Method

Abstract

One of the most widely utilized absorbing boundaries for the finite difference frequency domain (FDFD) method is the perfectly matched layer (PML); however, this boundary is not ideal, as it significantly increases the computational complexity of a simulation. We compare three alternatives to the PML for modal solution using the FDFD method: the Higdon absorbing boundary condition, the complementary operators method, and the transparent absorbing boundary. These methods are integrated into an FDFD algorithm and applied to a well-known ridge waveguide test structure. The errors introduced by the absorbing boundaries are quantified in terms of propagation constant error and modal distortion, and compared to reported results using the PML.