Finite difference time domain modeling of optical devices.

Abstract

A series of enhancements are made to the standard finite difference time domain (FDTD) approach which allow for new classes of problems to be modeled. These enhancements include material models for dispersive linear and nonlinear media, a new source formulation, which provides a means for driving an incident beam along a total field/scattered field boundary, and an efficient near to far field transform based on a Huygen's equivalent source reconstruction. The dispersive material improvements to the FDTD approach include the linear Lorentz, the nonlinear Raman, and the instantaneous Kerr models. Incorporation of the Lorentz dispersion model allowed us to model scattering from good conductors such as the noble metals (Au, Ag, Cu) in the optical regime. Following its theoretical development, the modified FDTD method is applied to three classes of problems: the modeling of nonlinear corrugated optical wave guide beam steering and output coupling devices, the rigorous treatment of metallic thin film diffraction gratings, and the modeling of tracking signals produced by realistic optical data storage disk geometries. Comparisons with mode matching analytical results and experimental data for realistic structures validate these FDTD improvements.