Magnetoplasmonic enhancement of Faraday rotation in patterned graphene metasurfaces

Faraday rotation is a fundamental property present in all nonreciprocal optical elements. In the THz range, graphene displays strong Faraday rotation; unfortunately, it is limited to frequencies below the cyclotron resonance. Here, we show experimentally that in specifically designed metasurfaces, magnetoplasmons can be used to circumvent this limitation. We find excellent agreement between theory and experiment and provide physical insights and predictions on these phenomena. Finally, we demonstrate strong tunability in these metasurfaces using electric and magnetic field biasing.