Dual-Tuned Terahertz Absorption Device Based on Vanadium Dioxide Phase Transition Properties

In recent years, absorbers related to metamaterials have been heavily investigated. In particular, VO₂ materials have received focused attention, and a large number of researchers have aimed at multilayer structures. This paper presents a new concept of a three-layer simple structure with VO₂ as the base, silicon dioxide as the dielectric layer, and graphene as the top layer. When VO₂ is in the insulated state, the absorber is in the closed state, Δf = 1.18 THz (absorption greater than 0.9); when VO₂ is in the metallic state, the absorber is open, Δf = 4.4 THz (absorption greater than 0.9), with ultra-broadband absorption. As a result of the absorption mode conversion, a phenomenon occurs with this absorber, with total transmission and total reflection occurring at 2.4 THz (A = 99.45% or 0.29%) and 6.5 THz (A = 90% or 0.24%) for different modes. Due to this absorption property, the absorber is able to achieve full-transmission and full-absorption transitions at specific frequencies. The device has great potential for applications in terahertz absorption, terahertz switching, and terahertz modulation.