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

A tunable broadband metamaterial absorber is proposed based on the vanadium dioxide and Fabry-Perot cavity in the terahertz region. To broaden the absorption bandwidth, the dielectric coating is employed on the top of vanadium dioxide squares to form the Fabry-Perot cavity for improving the impedance matching and further triggering an additional resonance frequency. The simulation results indicate that the bandwidth of absorption over 90% reaches 3.43 THz with a central frequency of 2.645 THz and the corresponding relative bandwidth is 129.7% under normal incidence. The absorption peak can be approximately tuned from 8% to 100% by changing the conductivity of vanadium dioxide. Moreover, it is polarization-insensitive, and exhibits absorption performance of working at wide-angle incidence. This design method can serve as a reference to research tunable and broadband terahertz devices.