Optical Absorption by Interlayer Density Excitations in Bilayer Graphene

Abstract

The optical absorption spectrum for light with electric field perpendicular to a bilayer graphene is shown to be quite different from that for parallel polarization. This arises partly from the difference in the selection rule and from the important depolarization effect due to induced polarization. The depolarization effect is most prominent for the sharp transition between the lowest to the first excited conduction band, which are almost parallel to each other.