Graphene for highly tunable non-reciprocal electromagnetic devices

The possibility of realizing highly tunable non-reciprocal devices with graphene is explored. Magnetically-biased graphene exhibits strong Faraday rotation at microwave frequencies and supports highly-confined edge magneto-plasmons at THz and infrared frequencies. The Faraday rotation direction and the edge along which magneto-plasmons propagate depend on both the type of charge carriers and the applied magnetic field. The type of charge carriers can be controlled via an electrostatic potential applied between graphene and an electrode beneath it. Two possible applications are proposed: a spatial isolator and a non-reciprocal plasmonic coupler. In both cases the isolation and the coupling directions can be electrostatically controlled while keeping the magnetic field unchanged.