Polarization tunable terahertz plasmon induced transparency in graphene ring-rod metamaterial

A periodic two-dimensional metamaterial with plasmon induced transparency effect in terahertz region, composed of polyimide layer covered by a monolayer graphene ring-rod structure, is presented and numerically investigated. The structure shows a remarkable polarization-sensitive transparent window in terahertz band due to the interference phenomenon caused by mode coupling. The results demonstrate that the transparent window of plasmon induced transparency can be flexibly controlled by adjusting the Fermi level of graphene and the polarization angle of incident terahertz wave, which are verified by numerical simulation and dipole-dipole interaction model. Moreover, the maximum group delay time corresponding to the polarization angle at 0 degree is 136.57 fs, exhibiting obvious slow light characteristics. The proposed metamaterial may give rise to practical application in terahertz switches and slow light devices.