摘要
Surface plasmons(SPs),or SP polaritons,are electromagnetic(EM)surface waves that propagate freely along metal-dielectric interfaces while being tightly localized in the perpendicular direction due to the interaction with collective oscillations of electron plasma in the metal[1].Therefore,SPs become two-dimensional(2D)manifestations of EM waves,with potentially very large wavenumbers near the SP resonance,thereby paving the way for many exciting phenomena,such as light focusing beyond the notorious optical diffraction limit and directing EM energy to the nanoscale[2].
