Preconditioned Finite-Difference Frequency-Domain for Modelling Periodic Dielectric Structures - Comparisons with FDTD

Finite-difference techniques are very popular and versatile numerical tools in computational electromagnetics. In this paper, we propose a preconditioned finite-difference frequency-domain method (FDFD) to model periodic structures in 2D and 3D. The preconditioner follows from a modal decoupling approximation. Its use involves discrete Fourier transforms (via FFTs). We have set FDFD against an FDTD package for a typical test case, with identical spatial grids. We have observed that computation times for a full frequency sweep are comparable, while the accuracy is slightly better with FDFD.