Light scattering by a medium with a spatially modulated optical   conductivity: the case of graphene
  We describe light scattering from a graphene sheet having a modulated optical conductivity. We show that such modulation enables the excitation of surface plasmon-polaritons by an electromagnetic wave impinging at normal incidence. The resulting surface plasmon-polaritons are responsible for a substantial increase of electromagnetic radiation absorption by the graphene sheet. The origin of the modulation can be due either to a periodic strain field or to adatoms (or absorbed molecules) with a modulated adsorption profile. 
N. M. R. Peres, A. Ferreira, Yu. V. Bludov, M. I. Vasilevskiy
cond-mat.mes-hall cond-mat.mtrl-sci physics.optics