Tunable multiple band THz perfect absorber with InSb metamaterial for enhanced sensing application

Abstract

A tunable multiple band THz metamaterial perfect absorber (MPA) is proposed and investigated numerically, which is believed to be applicable for both temperature and refractive index sensing in THz region. Distinct from previous designs, the proposed MPA is only consisted of a structured indium antimonide (InSb) metamaterial layer, a dielectric layer and a metallic layer. Numerical results demonstrate that three resonant peaks with 100% absorptance at 1.17 THz, 1.60 THz and 2.17 THz can be achieved simultaneously. The impedance matching theory, the electric field, surface current and magnetic field distribution are used to explain the physical mechanism of the MPA. It is worth to mention that the number of perfect absorption peaks can be flexibly tuned from two to five band though breaking the symmetry of patterned InSb array. Furthermore, the absorption property of the designed MPA is found to be highly sensitive to the variations of the surrounding mediums and fluctuations of external environment temperature. Thus, the proposed MPA can not only operate as a temperature sensor with a sensitivity of 22.0 GHz/K, but also a refractive index sensor with a sensitivity of 287 GHz/RIU (refractive index unit). Due to its high sensing performance, our proposed tunable multiple band THz MPA can be widely applied into the material detection, thermal biosensing and other related optoelectronic fields.

Keywords

• Metamaterial
• Perfect absorber
• Indium antimonide
• Multiple band