Dual‐State VO2–Graphene Tunable Terahertz Absorber for Broadband Absorption and Transmission Regulation
Abstract
Tunable terahertz (THz) absorbers require broadband response, dynamic control, and simple device architectures. Here, we propose a dual‐state VO2–graphene composite metasurface comprising one patterned graphene layer, a SiO2 dielectric spacer, and a VO2 substrate. The thermally induced insulator‐to‐metal transition of VO2 and the electrically tunable graphene Fermi level provide two independent control dimensions for absorption and transmission. At 345 K, the device achieves broadband absorption (A > 90%) from 3.00 to 7.25 THz, corresponding to a 4.25 THz bandwidth and an average absorptivity of 0.98. At 313 K, it retains moderate absorption and a tunable transmission response, enabling reversible absorption–transmission switching. Impedance matching and overlapping localized surface plasmon resonance (LSPR) modes account for the high‐temperature broadband absorption. The change in VO2 conductivity regulates the loss distribution and resonance coupling, whereas increasing the graphene Fermi level strengthens the plasmonic response and broadens the operating band. This design provides a feasible solution for multifunctional THz devices and has potential application value in intelligent thermal control, dynamic filtering, THz modulation, and sensing.