A Tunable Double-Decker Ultra-Broadband THz Absorber Based on a Phase Change Material

In this paper, a tunable double-decker ultra-broadband THz absorber is proposed based on a phase change material, which is vanadium dioxide (VO2). The tailored tunable double-decker phase change material absorber (TDPA) can be regulated by the temperature. The absorption of such TDPA spans from 7.36 to 16.67 THz when the temperature is equal to 350 K for TE wave, which is over 90% and its relative bandwidth is 77.4% under the circumstances. But such a TDPA can be regarded as a perfect reflector when the temperature is 300 K. When the incident angle is oblique, the absorption also is investigated, which shows that the presented TDPA is incident-angle-independent, when the incident angle is less than 40°. The relationship between the absorption features and the structure parameters is also discussed. The distributions of current surface, the electric fields, and the power loss densities are given to expound the physical mechanism of such a TDPA. Besides, by setting different temperature, a reconfigurable device can be realized in the proposed TDPA.