  Monolayer graphene absorbs 2.3 percent of the incident visible light. This
'small' absorption has been used to emphasize the visual transparency of
graphene, but it in fact means that multilayer graphene absorbs a sizable
fraction of incident light, which causes non-negligible fluorescence. In this
paper, we formulate the light emission properties of multilayer graphene
composed of tens to hundreds of layers using a transfer matrix method and
confirm the method's validity experimentally. We could quantitatively explain
the measured contrasts of multilayer graphene on SiO$_2$/Si substrates and
found sizable corrections, which cannot be classified as incoherent light
emissions, to the reflectance of visible light. The new component originates
from coherent emission caused by absorption at each graphene layer. Multilayer
graphene thus functions as a partial coherent light source of various
wavelengths, and it may have surface-emitting laser applications.
