Monolayer graphene photonic metastructures: Giant Faraday rotation and nearly perfect transmission

We demonstrate a heterogeneous photonic metastructure involving monolayer graphene achieving a substantial Faraday rotation angle and nearly perfect transmittance simultaneously. This breaks the longstanding tradeoff between the Faraday rotation angle and the transmission coefficient in conventional magneto-optical devices. Faraday rotation is enhanced across the interface between two photonic crystals due to the presence of an interface mode, i.e. optical Tamm state, which presents a strong electromagnetic field confinement at the location of the graphene sheet. This interface mode also helps to maintain a nearly perfect optical transmission through the structure thanks to a resonant tunneling mechanism. This exciting result was achieved particularly in the quantum regime with low Fermi level.