Dynamic switching: vanadium dioxide and graphene-based terahertz perfect absorber for tunable broadband absorption and tri-band absorption

Abstract In this paper, a dual-function switchable perfect absorber in the terahertz band is simulated and proposed. The design leverages the phase transition properties of vanadium dioxide (VO 2 ) and the dynamically tunable properties of graphene. The absorber exhibits broadband absorption when VO 2 is operated in the insulating state alone, with a bandwidth of 7.09 THz and a high modulation depth of 99.45% resulting in absorption levels above 90%. Additionally, by operating the graphene square ring and the graphene round ring at the Fermi levels of 0.72 eV and 0.75 eV, respectively, the absorber demonstrates tri-band absorption, making it suitable for refractive index sensing applications. The absorber’s operating frequency can be easily tuned by adjusting the conductivity of VO 2 and the Fermi levels of graphene, enabling dynamic tunability. The feasibility of our work positions it as a promising candidate for designing switchable broadband and multi-band absorbers. Consequently, our research holds significant potential for applications in terahertz devices.