Wideband tunable terahertz metamaterial absorber based on vanadium dioxide (VO2) for terahertz sensing and communication

A broadband tunable terahertz metamaterial absorber based on vanadium dioxide (VO2) is proposed in this work. The absorber adopts a simple sandwich architecture consisting of a patterned top layer with two discrete resonators, a gold reflector as the bottom layer, and a dielectric spacer in between. By exploiting the insulator–metal phase transition of VO2 induced through chemical doping and thermal control, dynamic tunability of the absorption response is achieved. The absorber demonstrates a novel dual-state resonator architecture in which bandwidth reconfigurability is governed by spatial restructuring of conductive regions rather than conventional single-state material tuning. In the metallic state of VO2, the first configuration exhibits an effective absorption bandwidth of 6 THz with absorptance exceeding 90% from 3.98 THz to 9.99 THz. Conversely, when VO2 is in the insulating state, the structure shows nearly total reflection over the same frequency range. In the second configuration, the absorber operates as a narrowband device with a bandwidth of only 0.2 THz centred at 5.5 THz. The underlying physical mechanism is investigated through electric field distribution and power loss density analyses. Furthermore, the absorber performance is evaluated under varying polarisation angles and oblique incidence for both TE and TM modes. Parametric studies reveal that the absorption characteristics are highly sensitive to the geometric dimensions, confirming the structural dependence of the absorber efficiency. • Contributions of the research: • The Vanadium Dioxide based dynamically tunable terahertz metamaterial absorber is proposed using a simple dual-resonator architecture enabling control via phase transition. • The absorber enables reconfigurable broadband and narrowband operation, achieving over 90% absorbance from 3.98 THz to 9.99 THz in the metallic state and a high-Q narrowband response of 0.2 THZ centered at 5.5 THz. • The structure exhibits switchable absorption–reflection functionality, behaving as a nearly perfect reflector when VO 2 is in the insulating phase. • The underlying absorption mechanism is systematically analysed using electric-field distributions and power-loss density, revealing strong resonance localisation and VO 2 -induced dissipative loss. • The proposed absorber maintains stable performance under varying polarisation and oblique incidence for both TE and TM modes, with parametric studies confirming high geometric tunability and design robustness.