Numerical analysis of periodic structures for microwave and infrared applications with the finite-difference time domain (FDTD) method

The primary emphasis of this dissertation is to develop efficient time domain numerical algorithms to investigate the scattering and transmission behaviors of artificial periodic structures. The discussion focuses on several difficulties in the numerical analysis of periodic structure and includes three main topics: (1) modeling of the periodic structure in the nano-scale, (2) modeling of periodic structure due to oblique plane wave incidence, and (3) modeling of periodic structure due to a non-periodic, finite-source excitation. With regard to these subjects, several novel techniques have been proposed and applied to the finite-difference time-domain (FDTD) method.; To analyze the nano-scale periodic structure for infrared (IR) applications, a Lorentz-Drude model is incorporated into the FDTD method to characterize metal film frequency-dependent electrical behavior at the IR wavelength using a Z-transform technique. The predicted results are compared with measured data, and good agreement is reported.; A novel FDTD algorithm with a simple periodic boundary condition (PBC) is developed to analyze the electromagnetic transmission/reflection for general periodic structures with arbitrary incident angles. The basic idea is to use a constant horizontal wave number in each FDTD simulation. The implementation procedure is introduced, and its validity is shown through several numerical examples.; Two novel time domain methods, which are based on spectral domain source transformation in conjunction with the finite-difference time-domain (FDTD) method, are developed. They are used to investigate the propagation and scattering behaviors of artificial periodic arrays due to arbitrarily shaped electromagnetic source illumination. Using these methods, only a single periodic cell must be modeled in finite difference time-domain computation. The error and convergence analyses are discussed in detail. Several periodic structures are analyzed using the proposed method to verify their computational efficiency in terms of computer memory and computing time.