Plasmon-Enhanced Spin–Orbit Interaction of Light in Graphene

A novel theoretical framework is developed describing polariton-enhanced spin–orbit interaction (SOI) of light on the surface of 2D media. The reduced dimensionality of the system is exploited to introduce a quantum-like formalism particularly suitable to fully take advantage of rotational invariance. Conservation of total angular momentum upon scattering enables the physical unveiling of the interaction between radiation and the 2D material along with the detailed exchange processes among orbital and spin components. In addition, the formalism is specialized to doped extended graphene, finding such an SOI to be dramatically enhanced by the excitation of plasmons propagating radially along the graphene sheet. Several examples of the enormous possibilities offered by plasmon-enhanced SOI of light are provided including vortex generation, mixing, and engineering of tunable deep subwavelength arrays of optical traps in the near field.