A Miniaturized Penta-band Metamaterial THz Absorber for Sensing and Imaging Applications

This paper presents the concept and design of a THz perfect metamaterial absorber (PMA) with a small footprint. The proposed PMA is developed on a polyimide substrate with a dielectric constant of 3.5. The unit cell PMA has four coupled arms with asymmetric convolution. The coupling between the arms defines the operational characteristics of the PMA. The proposed PMA is miniaturized with an asymmetric coupled arm with a physical dimension of 41 × 41 μm. The electrical size of the PMA is0.133λo × 0.133λo, where λo is highest operating wavelength. The proposed PMA offers five distinct absorption peaks at 0.97, 1.98, 2.65, 3.76, and 4.51 THz with absorptivity more than 98%. The PMA has a symmetrical configuration, and hence offers polarization-independent operation with angular stability up to 60°. The calculated average sensitivity and peak sensitivity of the five-band PMA are 17 GHz/PU and 88.5 GHz/PU at 2.95 THz respectively. The variations in sensitivity for different sample thicknesses is smaller than6 GHz/μm in all the realized bands.