All-Dielectric Dual-Band Metamaterial Absorber Based on Ring Nanocavity in Visible Region for Sensing Applications

In this study, an all-dielectric metamaterial absorber consisting of a ring nanocavity array, a spacer layer, and a metallic substrate is designed and investigated. The simulation results show that the two perfect absorption peaks (99.91% and 99.96%) are achieved at 539 nm and 673 nm. The two resonance modes caused by the different electric and magnetic field distributions of the ring nanocavity structure lead to different absorption and sensing properties. In addition, the influence of the structural parameters, such as the width of the nanocavity, on the sensing characteristics was studied and is presented here. A high sensitivity and narrow band result in a huge figure of merit when the proposed absorber is operated as a refractive index sensor.