Terahertz metamaterial absorber based on a square ring for sensing applications

We present a terahertz metamaterial absorber based on a square ring for sensing applications. This structure consists of three layers, namely, a square ring resonator, an intermediate dielectric layer, and a metal substrate from top to bottom. The simulated data show that the absorber has a strong absorption peak at 0.661 THz with an absorption rate of over 99.96%. The physical mechanism of absorption is clarified by the electric field distribution, the surface current distribution, and surface power loss density. The effect of the structural parameters on the absorption performance is also analyzed and optimized. In addition, we investigate the sensing characteristic of the absorber. It turns out that the Q-factor of the proposed metamaterial absorber is 31.50, the figure of merit value is 7.72 RIU−1, and the refractive frequency sensitivity is as high as 161.99 GHz/RIU. The refractive frequency sensitivity exceeds those of the majority of terahertz absorbers with absorption peaks between 0.1 and 1 THz. These good results show that it has penitential application in the field of sensing and detection.