Double-negative electromagnetic metamaterials due to chirality

The paper aims to explain how a double-negative refractive index can arise in chiral materials. It focuses on a mechanism that avoids needing two different kinds of subwavelength resonators. Instead, it considers media made from only one type of dielectric resonant element. The authors argue that the chirality of the surrounding background medium can drive double-negative behavior, leading to negative refraction and superlens-like performance. Using plasmonic dielectric particles, the paper states that both effective electric permittivity and effective magnetic permeability can become negative near certain resonant frequencies. It also provides a justification for modeling a plasmonic particle in a chiral medium as a combination of resonant electric and magnetic dipoles, and characterizes the resonant frequency set. Finally, it states that with an appropriate particle volume fraction and configuration conditions, a double-negative effective medium can be obtained when operating near one of the resonant frequencies.