Ultra-wideband terahertz metamaterial absorber with polarization insensitivity and broad incidence angle absorption

Abstract Terahertz metamaterials absorbing materials (TMAs) are a subject of interest due to their capacity to absorb specific electromagnetic waves. This study proposes an ultra-wideband perfectly absorbing metamaterial absorber (MMA) with polarisation insensitivity and wide incident absorption angle for the terahertz (THz) band. The TMA employs vanadium dioxide(VO 2 ) as the resonant layer, obstructing electromagnetic waves from traversing the metamaterial via a gold substrate to create a straightforward Fabry–Perot asymmetric resonant cavity and broadening the bandwidth through the incorporation of a square frequency selective surface (S-FSS) array. The experimental simulations demonstrate that the TMA exhibits an ultra-wide absorption bandwidth of 9.54 THz, with up to 90% absorption within the 2.9–12.44 THz range. Furthermore, the tunability of VO 2 conductivity has been leveraged to achieve a controllable absorption range of 5%–99%. The incident angle sensitivity of TMA to TE and TM polarisation was subjected to further investigation. It was observed that the TMA can sustain a relative bandwidth exceeding 66% and an absorption rate surpassing 90% in the 60° region. Additionally, it can achieve a relative bandwidth of up to 129.4% at an incidence angle of 40°. It can therefore be concluded that the perfect absorber with ultra-wide absorption bandwidth, as designed in this study, has potential applications in optical tunable absorber devices and other fields.