Even and odd modes in coupled graphene nanoribbons

Dispersion, attenuation and characteristic impedance of the fundamental modes supported by a pair of identical graphene nanoribbons in free space are studied. An efficient full-wave approach is adopted, based on a method-of-moments discretization of the relevant electric-field integral equation in which the graphene is modeled through a simple local conductivity. A spatial-domain formulation is adopted as it allows for efficiently treating nanoribbons with wide transverse separations and having in mind future treatment of spatially nonuniform graphene conductivities.