Metasurface inverse designed by deep learning for quasi-entire terahertz wave absorption

Thermal controlled multi-functional metasurface for freely switching of absorption, reflection, and transmission

Metasurfaces have garnered significant attention in recent years due to their substantial electromagnetic (EM) wave manipulation capabilities. However, most previously documented metasurfaces have been limited to controlling just a single EM wave mode, encompassing transmission, reflection, or absorption. Such limitations have impeded the broader applications of metasurfaces. To address this issue, this study introduces a multi-functional metasurface (MFM) in the utilization of Ge2Sb2Te5 (GST), vanadium dioxide (VO2), and graphene. This novel design enables real-time control over the transmission, absorption, and reflection of EM waves as necessitated through thermal control, allowing for seamless transitions from complete transmission to complete reflection. Furthermore, this configuration achieves extensive broadband perfect absorption, spanning up to 1.83 THz. The optical response mechanism of this MFM across distinct operational modes is meticulously analyzed through electric field distribution. Remarkably, this proposed MFM exhibits polarization insensitivity and maintains good optical performance even under conditions of wide-angle incidence. With the ability to switch to different operating modes according to the needs of different environments, the proposed MFM has the potential to be used in a wide range of scenarios, including radar stealth, wireless communications, and military search.