  A subcell technique for calculation of optical properties of graphene with
the finite-difference time-domain (FDTD) method is presented. The technique
takes into account the surface conductivity of graphene which allows the
correct calculation of its dispersive response for arbitrarily polarized
incident waves interacting with the graphene.The developed technique is
verified for a planar graphene sheet configuration against the exact analytical
solution. Based on the same test case scenario, we also show that the subcell
technique demonstrates a superior accuracy and numerical efficiency with
respect to the widely used thin-film FDTD approach for modeling graphene. We
further apply our technique to the simulations of a graphene metamaterial
containing periodically spaced graphene strips (graphene strip-grating) and
demonstrate good agreement with the available theoretical results.

Mesoscale and Nanoscale Physics;Optics