Design of a six-band terahertz metamaterial absorber for temperature sensing application

We present a simple design of a six-band terahertz metamaterial absorber (MMA). The unit-cell of the MMA consists of a metallic cross-cave-patch (CCP) structure and an InSb dielectric spacing layer stands on a ground plane. The permittivity of the InSb dielectric layer can be adjusted efficiently by the variation of external temperature. The numerical simulation results show that the MMA has six distinct absorption peaks from 0.4 THz to 2.2 THz, and the absorption peak frequencies can be tuned easily by changing the external temperature. The surface current distributions of the top layer and back layer of the unit-cell structure are studied to better understand the physical mechanism of the proposed MMA. The six-band strong absorption of the MMA is originated from the excitations of high-order magnetic resonance. In addition, the sensitivity S is investigated to explore temperature sensing performance of the device, and the value of S is 10.3 GHz/K, 8.1 GHz/K, 6.7 GHz/K, 6.4 GHz/K, 5.5 GHz/K and 5.4 GHz/K, respectively. The design of the MMA could find potential applications in temperature sensing or other optoelectronic related areas in terahertz region.