  We analyze the spectroscopic features of bilayer graphene determined by the
formation of pairs of low-energy and split bands in this material. We show that
the inter-Landau-level absorption spectrum in bilayer graphene at high magnetic
field is much denser in the far-infrared range than that in monolayer material,
and that the polarization dependence of its lowest energy peak can be used to
test the form of the bilayer ground state in the quantum Hall-effect regime.
