Design of an ultra-thin hepta-band metamaterial absorber for sensing applications

Abstract

An ultra-thin metamaterial absorber (MMA) comprises of a split-ring-cross (SRC)-shaped resonator coupled with graphene and dielectric layer backed by metallic ground plane is presented theoretically and numerically for hepta-band applications. The proposed absorber demonstrates multiple absorption peaks at 2.33, 5.24, 7.74, 8.25, 10.05, 10.97, and 12.61 THz with average absorption of more than 96%. The physical mechanism of the hepta-band absorption is analyzing by electric field distribution and attributed to the combination of dipolar and LC resonance. Furthermore, the effect of geometric parameters is analyzed to validate the optimal selection of the structural parameters. In addition, the proposed MMA is analyzed for different incident and polarization angles suggesting that absorption response is insensitive to polarization angles. Compared with the previously reported MMAs, the proposed design is ultra-thin (0.036λ) and compact (0.21λ) at the lowest operational frequency. The absorptivity at 12.61 THz is 99.81% and the corresponding quality (Q) factor is 31.52 for a bandwidth of 0.40 THz. The proposed absorber can be potentially utilized in detection, sensing, and imaging. Moreover, the sensing performance of the proposed MMA has been investigated using overlayer thickness and overlayer permittivity.