Visibility of graphene flakes on a dielectric substrate

The authors model the optical visibility of monolayer and bilayer graphene deposited on a $\mathrm{Si}{\mathrm{O}}_2∕\mathrm{Si}$ substrate or thermally annealed on the surface of SiC. Visibility is much stonger in reflection than in transmission, reaching the optimum conditions when the bare substrate transmits light resonantly. In the optical range of frequencies a bilayer is approximately twice as visible as a monolayer thereby making the two types of graphene distinguishable from each other.