Strong and broadband terahertz absorber using SiO₂-based metamaterial structure

Abstract

We design and experimentally demonstrate a broadband metamaterial absorber in the terahertz (THz) band based on a periodic array of aluminum (Al) squares with two different sizes. A thin silicon dioxide (SiO2) film rather than a conventional polyimide (PI) layer is used as a dielectric spacer to separate Al squares from the platinum (Pt) ground plane in our design, which significantly improves the design precision and the feasibility of the device fabrication. The combination of different sizes of Al squares gives rise to an absorption bandwidth of over 210 GHz with an absorption of over 90%. Our results also show that our device is almost polarization-insensitive. It works very well for all azimuthal angles with an absorption of beyond 80%.