▎ 摘　　要

Effects of electron-electron interactions on the optical response of graphene nanoribbons are theoretically investigated in an effective-mass approximation in a comprehensive manner. In optical absorption spectra of armchair and zigzag nanoribbons without and with doping, excitons, which are bound states of electrons and holes, and plasmons manifest themselves as various prominent peaks. For light polarized parallel to nanoribbons, exciton peaks at high energies split because of interactions with dark excitons, to which optical transition is prohibited. For light polarized perpendicular to nanoribbons, in nondoped semiconducting armchair nanoribbons, moderate exciton peaks appear while in doped armchair and zigzag nanoribbons, only when the Fermi energy crosses at least two energy bands, large plasmon peaks occur because of a nature of Dirac electrons. These peaks can be assigned to specific optical transitions in energy bands. The optical absorption peaks arising from the excitons and plasmons in a wide range of categories of nanoribbons approximately correspond to those of carbon nanotubes by appropriate scaling of energy and the wave vector.