Numerical Modeling of Pseudo-isotropic Negative Refractive Index Media

摘要

The concept of negative refraction promises to rewrite the electromagnetic textbooks due to its corresponding unprecedented properties including inverse Snell's law, inverse Doppler shift, and inverse Cherenkov radiation. Recently, the first demonstration of negative refractive index media (NRIM) was realized by D.R. Smith et al. who integrated two respective sets of sub-wavelength resonant structures (i.e., plasmonic wires and split-ring resonators) to exhibit negative electric permittivity and magnetic permeability simultaneously. More recently, other resonant structures made of a single set of unit cells also suggested negative refraction phenomena, enabling to ease the fabrication. Yet, all those resonant structures behave anisotropically and thereby, currently it is still challenging to realize negative refraction for different exciting incidences such as grazing-angle and normal incident configurations. In this paper, we design and simulate a monolithic set of double-layer resonant structures not only possessing negative refraction, but also simultaneously responding to both grazing-angle and normal incident excitations within microwave region. In accordance with the results of S-parameter simulation and the retrieved material properties, we clearly observe two allowed narrow bands to indicate the existence of pseudo-isotropic NRIM (PINRIM). Our results show that the designed monolithic set of double-layer structures can extensively broaden the valuable applications of negative refraction owing to its pseudo-isotropic response.