Implementation of Gaussian beam sources in FDTD for scattering problems

In this paper, we present an implementation of a Gaussian beam source in the FDTD by using a modified version of the total-field/scattered-field (TF/SF) formulation. Such a source finds many practical applications in the context of the FDTD simulation, such as scattering by rough surfaces and photonic crystals. Numerical examples are presented to illustrate the scattering of a Gaussian beam from a homogenous dielectric slab, as well as from a metamaterial slab containing split-ring and dipole type of inclusions, embedded in a background medium.