A tunable broadband terahertz metamaterial absorber based on the vanadium dioxide

A tunable broadband terahertz (THz) metamaterial absorber which is based on the vanadium dioxide (VO2) is presented in this paper. The proposed absorber is composed of VO2 resonators, polyimide dielectric layer and Au reflective layer, whose absorption spectra can be tailored by the variation of the external temperature. The absorption of such an absorber is broadband, which exceeds 90% in the frequency range of 4.29 THz-5.52 THz when the kelvin temperature (t) is equal to 350 K and its relative bandwidth is reach to 25.1%. However, when t is 300 K, the designed absorber can be acted as a perfect reflector. In order to better understand the physical mechanism, the electric field, surface current distribution and power loss density of such an absorber are investigated. The effects of structure parameters and incident angle on absorption spectra are also discussed. The simulated results demonstrate that the absorption performance can be altered by controlling the values of structure parameters and incident angle. Such a tunable broadband absorber has potential applications in photocatalysts, thermal emission and solar cells.