Optical left-handed metamaterials made of arrays of upright split-ring pairs

The abstract discusses electromagnetic metamaterials that can show negative refraction (a negative refractive index) and focuses on the harder optical-frequency case of left-handed metamaterials, which require both negative permittivity and negative permeability. The authors propose a new design: an array of simple upright split-ring pairs intended to work in the near-infrared. They explain that coupling between the two rings can simultaneously trigger electric and magnetic resonances. Using electromagnetic simulations, they report a highest refractive index of -2, a highest figure of merit of 21, good air-matched impedance, and a 180 nm double-negative bandwidth. They also numerically demonstrate negative refraction for both a single-layer structure and a wedge-shaped lens.