A temperature-controlled tunable plasmonic dual-band absorber

A plasmonic dual-band absorber based on a three-layer metal-dielectric-metal structure with an gold elliptical nanodisk array arranged on the top layer is designed and fabricated. Nearly 100% absorption is achieved at dual frequencies in near infrared range due to the plasmonic resonances of incident light and gold elliptical nanodisks along major and minor axes. The designed structure is fabricated by electron beam lithography and the measured reflection spectra match well with simulations. Moreover, it shows that the two absorption peaks can be effectively tuned by coating a temperature-controlled nematic liquid crystal layer on top of the device. The tuning process is simple and repeatable with a maximal tuning range of 22 nm. Owing to its high absorption efficiency and tunable property, this plasmonic absorber must have a great potential in the research field such as solar cells and future photonic circuits.