Numerical modeling of periodic structures: Metallic grids and metamaterials

Recent interest in the propagation of electromagnetic waves in materials with subwavelength periodic structures has underscored the need for efficient and rigorous modeling of these devices. This work presents the use of rigorous coupled-wave analysis (RCWA) algorithm to model periodic structures. The main focus of the investigation is the use of this algorithm to study subwavelength metallic inductive and capacitive grids (also known as crossed gratings). The applicability and limitations of RCWA as applied to metallic crossed gratings are discussed, and numerical results are validated with experimental data.; In order to gain insight into physics of these subwavelength metallic grids, the RCWA algorithm is complemented with the physically intuitive surface plasma wave (SPW) model. It is shown that the salient features of the transmission spectra of these structures can be explained on the basis of SPW model. This is true for inductive as well as capacitive grids.; Finally, the RCWA algorithm and the SPW model are applied to investigate metamaterials/negative index materials. It is shown that grating fields can propagate unchanged in presence of negative index materials, and the excitation of SPW on metallic films can improve the near-field image of an object.