▎ 摘　　要

The low-frequency optical response of graphene nanoribbons can be enhanced and tuned by a spatially modulated magnetic field. The absorption spectrum exhibits rich asymmetric peaks corresponding to the oscillatory behavior in energy bands. The optical selection rule, dominated by magnetic and quantum confinements, is clarified by examining state wave functions. The dependence of the optical excitations on field strength and period is studied as well. These results provide possibility for employing graphene nanoribbons in future optoelectronic applications. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467038]