Controlling plasmon-induced transparency of graphene metamolecules with external magnetic field.

We numerically demonstrate dynamically tuneable plasmon-induced transparency in a π-shaped metamolecules made of graphene nanostrips by applying external static magnetic field. It is shown that for graphene nanostrips with appropriate Fermi energy, the resonant wavelength, line-shape, and the polarization of transmitted light in the mid-infrared can be effectively controlled by magnetic field. In particular, giant polarization rotation exceeding 20° has been observed in asymmetric graphene metamolecules, which is further enhanced to almost 40° due the Faraday effect in the applied magnetic field, at around 9 μm wavelength, much higher frequency than the Faraday rotation observed in a semi-infinite graphene microribbons. The results offer a flexible approach for the development of compact, tunable graphene-based photonic devices.