▎ 摘 要
The low-frequency optical excitations of a monolayer graphene in a periodic magnetic field are calculated by the gradient approximation. The original and extra band-edge states make the optical-absorption spectra exhibit a lot of asymmetric prominent peaks, which, respectively, lead to the principal peaks and subpeaks. The two kinds of peaks obey two different selection rules because their wave functions present different features. The intensity, frequency, and number of the absorption peaks are related to the period, strength, direction of a modulated magnetic field, and the electric polarization direction. The anisotropic absorption spectra are induced by the different modulated directions and electric polarization directions. The above-mentioned results could be verified by the optical measurements.