A novel graphene metamaterial design for tunable terahertz plasmon induced transparency by two bright mode coupling

A novel graphene-based metamaterial for terahertz plasmon induced transparency (PIT) is presented in this paper, which consists of a graphene ring and a graphene strip compound structure. Both the ring and strip are performed as bright modes which are induced by electric dipole resonances, respectively. The weak hybridization between two elements leads to a novel PIT window. The PIT window can be controlled by adjusting the geometric parameters of graphene-based metamaterial structure. More importantly, the resonant frequency of transparency window can be dynamically tuned over a broad frequency range by varying the Fermi energy of graphene through controlling the electrostatic gating instead of refabricating the structures. Correspondingly, through adjusting the Fermi energy of graphene, a large group delay could also be observed, reaching up to 0.5 ps at the transparent peak. These results may offer great promise for tunable terahertz switching, slow light device, and sensing technology.