Simulation and analysis of non-periodic and random metamaterial structures

Abstract

The concept of using negative refractive media for a perfect lens was theorized by Veselago in 1968 (Sov. Phys. Usp., 10, 509–514). Recent developments in metamaterials (Shelby et al., Science 292, 77, 2001) allowed researchers to physically demonstrate that artificial composite media can be engineered to exhibit exotic properties, including negative refractive index, by exploiting features in arrays of sub-wavelength unit cells. These unconventional electromagnetic properties are realized through the couplings of the microscopic unit cells, which govern the macroscopic properties of the structure. Our study focuses on electromagnetic propagation in media in which the effective relative permittivity and permeability exhibit negative values, resulting in negative index of refraction over a given frequency range. These composite structures are engineered to act as a medium supporting electromagnetic wave propagation in which the direction of phase velocity is opposite to the direction of energy flow (Depine and Lakhtakia, Microw. Opt. Technol. Lett., 41, 315–316, 2004). Generally, metamaterial structures are comprised of resonant inserts, such as split ring resonators (SRRs), that are periodically arranged (Singh et al., J. Opt., 12, 015101, 2010). However, these structures have been limited by their narrow operational bandwidth, high loss, and isotropic limitations (Caloz, Materials Today, 12(3), 12–20, 2009).