Double-negative electromagnetic metamaterials due to chirality

TL;DR

This paper develops a mathematical framework showing how chiral media with dielectric resonators can exhibit double-negative refractive indices, enabling superlensing without the need for multiple resonator types.

Contribution

It introduces a novel theory demonstrating that chirality alone can induce double-negative metamaterials using a single resonator type, expanding design possibilities.

Findings

Negative permittivity and permeability near resonant frequencies

Double-negative behavior achieved with specific particle configurations

Resonant frequencies characterized mathematically

Abstract

The aim of this paper is to provide a mathematical theory for understanding the mechanism behind the double-negative refractive index phenomenon in chiral materials. The design of double-negative metamaterials generally requires the use of two different kinds of subwavelength resonators, which may limit the applicability of double-negative metamaterials. Herein, we rely on media that consist of only a single type of dielectric resonant element, and show how the chirality of the background medium induces double-negative refractive index metamaterial, which refracts waves negatively, hence acting as a superlens. Using plasmonic dielectric particles, it is proved that both the effective electric permittivity and the magnetic permeability can be negative near some resonant frequencies. A justification of the approximation of a plasmonic particle in a chiral medium by the sum of a resonant electric dipole and a resonant magnetic dipole, is provided. Moreover, the set of resonant frequencies is characterized. For an appropriate volume fraction of plasmonic particles with certain conditions on their configuration, a double-negative effective medium can be obtained when the frequency is near one of the resonant frequencies.