Metamaterials, Spatial Dispersion, and Negative Refraction (Preprint).

摘要

Spatial dispersion, anisotropy, and negative refraction with negative group velocity have been observed in metamaterials. Spatial dispersion occurs when permittivity epsilon(omega, kappa) and permeability mu(omega, kappa) are dependent on frequency, omega, and wave vector, kappa, related to a fixed periodic potential along a lattice. The potential along the lattice results from an exciton, resonance, or atomic polarization forming an electric dipole moment. The dipole moments produce a spatially dispersive longitudinal and transverse wave allowing an incident, longitudinal and transverse to exist in the metamaterial. The resonance of Split-Ring-Resonators (SRRs) in SRR-Wire- Post (WP) medium provides the dipole moment needed for spatial dispersion and mu is less than 0 for negative refraction. The WP is designed to have epsilon less than 0 at the resonant frequency of the SRR providing simultaneous epsilon is less than 0 and mu is less than 0 for negative refraction. We ran parametric simulations changing the geometric parameters of the SRR and WP and used the simulated results to demonstrate the coexistence of spatial dispersion and negative refraction in a SRR-WP medium. The results show the interaction of spatial dispersion and negative refraction in SRR-WP media. We show this by controlling the geometrical parameters of the SRR and WP conditions can be met to differentiate the behavior between spatial dispersion and negative refraction in the SRR-WP media.