Electromagnetic field analysis of dispersive media using frequency-dependent symplectic integrator

We have applied the symplectic integrator (SI) scheme based on the fast Fourier transform, namely, FFT-SI, to electromagnetic field analysis for inhomogeneous and dispersive media. The auxiliary differential equation (ADE) for chromatic dispersion was formulated along with the time-dependent Maxwell equations. We examined two distinct dispersion models for ADE: one based on Sellmeier equation and the other based on the Lorenz-Drude model. Our computational results for one-dimensional problems were compared with exact solutions to examine numerical accuracy with respect to the time and space step sizes, allowing us to assess applicability of higher-order algorithms and effects of numerical dispersion errors. Extension of the present computational method for two-dimensional problems used for application development was also examined.