Design of a compact polarization-insensitive multi-band metamaterial absorber for terahertz applications

This manuscript proposes a polarization-insensitive multi-band metamaterial (MTM) absorber for terahertz (THz) applications. The overall size of the proposed unit cell is 130 x 130 mu m(2), consisting of two metallic radiators at the topmost layer, a polyimide substrate in the middle, and a conducting ground plane at its back. The three concentric circular-shaped rings acting as resonators are modified to obtain the desired multi-band absorption. The simulated results show that the proposed absorber can offer 91.73%, 99.46%, 97.25%, 97.46%, and 95.42% absorption at the five different resonant frequencies of 0.668 THz, 0.926 THz 1.10 THz, 1.19 THz, and 1.33 THz, respectively. The electric and magnetic field distribution of the proposed absorber are also investigated to study its absorption mechanism in detail. Moreover, the proposed absorber is polarization insensitive due to its fourfold symmetry. The theoretical results confirm that the proposed absorber can offer a wide range of THz applications in sensing, filtering, and imaging.