Design of a Miniaturized Narrow-Band Absorber Based on Metallic Metamaterial at Terahertz Frequency

In this article, the design of a miniaturized narrow-band terahertz absorber is theoretically investigated. The designed absorber is made of an artificial dielectric layer (ADL) deposited on a substrate terminated by a metallic layer. The ADL includes two thin metal layers vertically separated by a thin dielectric film. Each metal layer is patterned to form a lattice of disconnected squares. The lattices on the two metal layers are shifted with respect to each other so that each square on the top lattice partially faces four squares on the bottom lattice. With a proper design of the structure parameters and utilizing the capacitive nature of ADL and the inductive property of the grounded dielectric spacer (substrate terminated by a metallic layer), the resonant frequency can be achieved at the terahertz regime. In this paper, a simple circuit model is presented for surveying the absorber behavior at normal incidence. The designed absorber shows perfect absorption around a center frequency of 0.4 THz with a quality factor of Q = 20. The proposed structure is polarization insensitive and shows absorption stability over a wide range of oblique incidence angles. Furthermore, the size of the proposed absorber is very smaller than other metallic absorbers at low terahertz frequency. The thickness of the structure is and the size of the unit cell is . Finally, a dual-band absorber can be realized using two layers of ADL.