A dynamically adjustable broadband terahertz absorber based on a vanadium dioxide hybrid metamaterial

A dynamically adjustable terahertz (THz) broadband absorber based on a vanadium dioxide (VO2) hybrid metamaterial is theoretically designed. During the design, we first consider working frequency, bandwidth, excitation method and fabrication process. And then, a commercialized full wave electromagnetic (EM) calculation software CST microwave 2019 based on finite integration technology is used to simulate and optimize the performance of the device. Due to the device is excited by light, it consists of a top layer of VO2 oblique-split ring-resonator (OSRR) array, a polyimide (PI) spacer and a bottom metal film. The simulation results show that, when the VO2 changes from insulating state to metal state under light stimulus, the absorption increases from 3% to over 90%. Meanwhile, when the VO2 is in metallic phase, the bandwidth of absorption greater than 90% reaches to 1.0 THz and the relative bandwidth is about 83%. The potential applications of the device are active EM stealth, THz wave detection and thermal imaging. This work paves a new way for simply constructing a low-cost dynamically adjustable THz broadband absorber.