Metamaterials absorber based on doped semiconductor for THz and FIR frequency ranges

Abstract

In this paper, we propose a metamaterials absorber for terahertz and far infrared frequency ranges. The elementary absorber structure consists of one dielectric layer stacked on one doped semiconductor layer without structure patterning. The ideal permittivity of the doped semiconductor layer for achieving perfect absorption is derived based on the impedance transformation method. Since the permittivity of the doped semiconductor can be tuned by doping, the impedance matching condition can be met at the desired frequency range. The simulation results show that the absorption reaches 97% at the impedance matching point. Furthermore, a broadband absorber can be formed by adding one pair of patterned dielectric-doped semiconductor layers on top of the elementary absorber structure. The average absorption of the broadband absorber reaches 95% from 8 THz to 14 THz. The proposed design, which is flexible and compatible with semiconductor technology, may find its applications in fields such as terahertz detection, imaging and bioanalytics.