Surface Plasmon Launching by Polariton Superradiance

The condition of phase matching prohibits the transfer of excitation from free-space photons to surface plasmon polaritons (SPPs). We propose and analyze a scheme that excites an ensemble of emitters in a collective state, which is phase matched with the SPP by the optical pulses used for its preparation. By a collective enhancement the ensemble, hence, emits an SPP in a well-defined direction. We demonstrate the scheme by analyzing the launching of near-infrared graphene SPP. Our theory incorporates the dispersive and dissipative properties of the plasmon modes to evaluate the non-Markovian emission by the ensembles and will also be applicable for other types of surface polaritons.