Perfect absorption in graphene multilayers

We demonstrate that 100% light absorption can be achieved in a graphene- based hyperbolic metamaterial, consisting of periodically arranged graphene layers which are tilted with respect to the interface. The geometrical parameters of the multilayered structure and the chemical potential of graphene are chosen in such a way that the in- plane relative effective permittivity is close to 1. Under this condition, the graphene multilayer exhibits asymmetry which appears as a very large difference between waves propagating upward and downward with respect to multilayer boundaries. One of them has a very high attenuation constant and neither of the waves undergo reflection at slab interfaces, resulting in total absorption even for an optically ultra- thin slab.