Broadband actively tunable metamaterial absorber based on vanadium dioxide and Fabry-Perot cavity

Abstract

The dynamic tunable broadband perfect absorber based on vanadium dioxide (VO2) is proposed in this paper. And the VO2 conductivity can be changed by temperature, thus changing the absorption characteristics of the absorber. Under normal incident conditions, absorption is more than 90% of the absorber in the range of 5.8–17.2 THz (THz), with an average absorption rate of more than 96%. And impedance matching theory and magnetic resonance theory are used to illustrate the mechanism of operation. The effect of the incidence angle on the absorption performance was studied, and the results show that the absorbers still maintain excellent absorption when the incidence angle is less than 45∘. In addition, the absorption characteristics of the absorber working in water are also studied. We demonstrate that the absorber's absorption is more than 90% in the range of 5–18 THz with an absorption bandwidth of 13 THz at a water depth of 5.2 μm. And by adjusting the VO2 conductivity, the average absorption rate can be adjusted from 2.5% to 96.1% with a water depth of 5.2 μm. The proposed structure has potential significant applications in the design of heat emitters, optical switches, cloaking devices, and energy harvesting devices.