We propose a thermally tunable and switchable terahertz (THz) absorber based on graphene- and vanadium dioxide (VO2)-included multilayers. VO2 is a phasechange material that undergoes a semiconductor-to-metal transition at a critical temperature of around 340 K, which can be exploited for designing absorbers. We investigate the optical properties of a few-layer structure that can achieve near-perfect absorption in the presence of the metallic VO2 layer at high temperatures. We also show that the absorption frequency can be actively adjusted by tuning the graphene layer characteristics. The absorption switches from near-zero to near-unity when the temperature changes from 300 K to 350 K, corresponding to the phase transition of VO2. Moreover, the absorption is sensitive to the incidence angle of the incoming light. Our proposed absorber has potential applications in intelligent and adaptive THz devices [1-4].
