Thermally tunable terahertz metamaterial absorber with switchable multi-band responses

Abstract Most metamaterial absorbers possess a fixed number of absorption peaks, which severely limits their application scenarios. In this study, we present a thermally tunable multifunctional terahertz metamaterial absorber, formed by a vandium dioxide and Au composited surface structure on top of a continuous Au film with a middle silicon layer, that allows for a controllable number of absorption peaks. By varying the operating temperature, the metamaterial absorber can actively switch between triple-band absorption and dual-band absorption, and their absorption mechanisms are discussed by using impedance matching theory and electric field distributions. Based on the VO 2 phase transition, the absorber can dynamically switch among single-band (narrow or broad), dual-band, and triple-band modes through polarization control. This capability enables the device to potentially achieve multiple optical switching functions, including single-frequency, dual-frequency, and triple-frequency optical switching. The multifunctional terahertz metamaterial absorber also demonstrates excellent sensing performance. It is anticipated that the proposed multifunctional absorber will offer great promise in optical switching, biosensing, and stealth.