▎ 摘　　要

We show theoretically that the optical conductivity of doped graphene can exhibit a spatially periodic modulation by a diffraction grating. Doped graphene placed above the grating exhibits a periodic electrostatic potential distribution, resulting in a periodic charge-density redistribution inside the graphene. The optical conductivity of doped graphene depends linearly on the Fermi energy, which is proportional to the square root of the charge density. Therefore, the optical conductivity exhibits a spatial-periodic modulation. The periodicity implies a band structure formation of the graphene plasmon polariton. Band engineering of the graphene plasmon polariton is also discussed. (C) 2015 Optical Society of America