Gold Nanowires-Based Hyperbolic Metamaterial Multiband Absorber Operating in the Visible and Near-Infrared Regimes

Spectral feature of gold nanowires-based hyperbolic metamaterial (NWHMM) absorber was investigated. The absorber has NWHMM surface as the top layer, which is composed of periodically arranged arrays of subwavelength-sized gold (Au) nanowires (of circular cross-section) immersed in silicon dioxide (SiO2)dielectric medium. Such NWHMM surface is over a planar dielectric SiO2 substrate, backed by a perfect (bottom) reflector comprised of nano-sized bulk layer of silver (Ag). Considering the incidence of electromagnetic waves (in the range of 400-1400nm wavelength) on the top NWHMM surface, the absorption spectrum of the proposed structure was analyzed for different thickness values (of surface), incidence angles, and also Au nanowire radius. The presence of multiple absorption peaks was noticed, which comes into existence due to different resonance conditions. The absorption features can be tuned by altering the operational conditions.