Dynamically Tunable Fano Metamaterials through the Coupling of Graphene Grating and Square Closed Ring Resonator

We present the numerical studies of a novel hybrid graphene-metal Fano metamaterial, which is composed of a graphene grating (graphene ribbon array) and a square closed ring resonator (SCRR) separated by a dielectric substrate. The destructive interference between the narrow and broad electrical dipolar surface plasmons induced respectively on the surface of the graphene ribbon and the SCRR leads to the classical analog of electromagnetically induced transparency (EIT). By decreasing the thickness of the substrate spacer (enhancing the coupling between the two components), a double EIT system could be achieved. More importantly, the transparency windows in the hybrid structures can be actively controlled by varying the applied gate voltage on the graphene ribbon. Large effective group index and small loss within the transparency windows suggest the promising slow-light applications.