An Ultra-thin, Switchable Ultra-narrow Band Absorber for High-performance Terahertz Sensing

Abstract

In this paper, an ultrathin terahertz metamaterial absorber consisting of Au pattern, polyimide and Au film is proposed. Based on the finite element method, the simulation consequences indicate that when its thickness is 9.4 m, there is a narrow absorption peak for the TE wave at 7.73 THz with near-perfect absorption of 99.8% and a full width at half maximum of 0.0896 THz, resulting from impedance matching and plasma resonance. And the absorption switching from a dual-band to a multi-band or a single-band to a dual-band absorption can be achieved for TM and TE waves by changing the incident angle or polarization angle. Furthermore, the absorption can also be switched from 99% to 0% by changing the polarization angles, and has a high tolerance of polarization angle down to more than 20 degrees. In addition, its application in the sensor is also studied at 7.73 THz, where its refractive index sensitivity and thickness sensitivity can achieve 1.2 THz/RIU and 0.065 THz/m, respectively. This might be utilized for monospectral imaging, biological diagnosis, and environmental monitoring.