Active manipulation of electromagnetically induced reflection in complementary terahertz graphene metamaterial

A graphene-based metamaterial,featuring a dynamically tunable terahertz electromagnetically induced reflection (EIR) window, is numerically investigated in this paper. The designed metamaterial consists of a graphene single layer perforated with wire-slot pair array and a split-ring resonator slot (SRR-slot) structures printed on a SiO2/Si substrate, where the wire-slot pair and SRR-slot structures can act as the superradiant and subradiant elements, respectively. The surface current distributions demonstrate that the destructive interference caused by strong near field coupling between two resonators can induce a sharp reflection peak. Through varying lateral displacement between two resonators within the unit cell, moreover, the reflection peak amplitude and the corresponding group delay can be actively controlled due to the electromagnetic energy transfer between two resonators. In addition, the reflection peak can also exhibit obvious blue-shift by changing Fermi energy of graphene. Therefore, the work opens up the possibility for the development of compact terahertz elements such as modulators, switches and slow light devices.