Dual‐State VO 2 –Graphene Tunable Terahertz Absorber for Broadband Absorption and Transmission Regulation

Tunable terahertz (THz) absorbers require broadband response, dynamic control, and simple device architectures. Here, we propose a dual‐state VO 2 –graphene composite metasurface comprising one patterned graphene layer, a SiO 2 dielectric spacer, and a VO 2 substrate. The thermally induced insulator‐to‐metal transition of VO 2 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 VO 2 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.