A high-performance broadband terahertz absorber based on single layer cross-shaped graphene

Abstract

In this paper, we propose an easy-to-fabricate, broadband terahertz (THz) absorber constructed by a single layer of cross-shaped graphene and a metallic mirror separated by a thin silicon layer. Over 90% absorption can be achieved at the frequencies from 1.5 THz to 3.0 THz, and even for oblique incidences of transverse electric (TE) and transverse magnetic (TM) polarized waves. The performance relies on structural parameters of the cross, thickness of the dielectric spacer, and internal parameters of graphene, such as Femi level and carrier mobility. Among the absorption band, two peak absorption comes from two graphene plasmonic modes, which can be understood as the hybridization of two dipoles either along the length or the width of two orthogonal rectangular arms. Our results will promote the development of graphene-based applications at THz and infrared regimes.