Dynamically Tunable Electromagnetically Induced Transparency-Like Effect in Terahertz Metamaterial Based on Graphene Cross Structures

A simple and multi-layer metamaterial made of graphene to realize excellent manipulation of EIT-like effect is proposed. The unit cell consists of four layers: Substrate 1, Cross 1, Substrate 2 and Cross 2, which can obtain tunable EIT-like effect by adjusting the Fermi level of graphene. The surface current distributions of four different views clearly explain the underlying physical mechanism. A three-level Λ-type system is employed to describe the coupling process between Cross 1 and 2. The calculated transmission spectra based on two-particle model have great agreement with the simulated transmission spectra. In addition, the effects of geometrical parameters on EIT-like effect are discussed and wideband EIT-like effect with high transmission can be obtained by adjusting the lengths of Cross 1 and 2. Also, the polarization-insensitive character of EIT-like metamaterial is confirmed by the transmission spectra under different polarization angles. The maximum of group delay (25.48 ps) is far greater than the group delay of previously reported EIT-like metamaterials. Our study provides a novel way for the development of slow-light devices and modulators.