Dynamically Tunable Broadband Terahertz Metamaterial Absorber Based on Vanadium Dioxide

In this paper. a vanadium dioxide (VO2) based tunable broadband terahertz (THz) absorber is designed on the silicon plane, which is composed of a VO2 resonator and a metal layer, separated by a thin silicon dioxide (SiO2) dielectric layer. Numerical simulation results show that VO2 with high conductivity (30000 Sim) is at its metal phase, and when its absorptivity is greater than 90%, the 2. 0 THz absorption bandwidth can he obtained. In addition, the perfect absorption is realized with absorptivity of 99. 3% and 99. 6% at 4. 5THz and 5. 8THz. respectively. In contrast, VO(2 )with low conductivity (100 S/m) is at its insulation phase, and the peak absorptivity in the corresponding broad absorption hand is only 8%. Therefore, by altering the conductivity of VO2 in the absorber, one can switch between absorption and reflection and realize the dynamic tuning of absorptivity in a broad frequency hand. In addition, the proposed absorber is polarization-insensitive under vertical incidence due to its structural symmetry. Moreover, the absorber maintains an excellent absorption performance over a wide incident angle range.