Simultaneous realizations of absorber and transparent conducting metal in a single metamaterial.

By introducing vanadium dioxide film into a multilayer structure, the dual functionalities of perfect absorption and high transmission are presented using the insulator-to-metal phase transition of vanadium dioxide. When vanadium dioxide is in the conducting state, the designed system acts as a narrowband absorber. The proposed absorber is composed of the top metallic ring, silica spacer, and the vanadium dioxide film. The absorption peak is originated from localized magnetic resonance between metallic ring and vanadium dioxide film. When vanadium dioxide is in the insulating state, the designed system acts as a transparent conducting metal. The top metallic ring, the middle dielectric spacer, and the subwavelength metallic mesh are combined together to form an antireflection coating. The influences of incident angle and structure parameter on absorption and transmission are also discussed. This work has demonstrated a new route for developing vanadium dioxide-based switchable photonic devices in the fields of filter and modulator at terahertz frequencies.