Optimum Surface Plasmon Excitation and Propagation on Conductive Two-Dimensional Materials and Thin Films

The surface conductivity of two-dimensional (2-D) materials and thin conductive films is considered for surface plasmon (SP) excitation and propagation. It is shown that an ideal surface conductivity exists to maximize the SP field at a given position, based on a tradeoff relating to propagation loss and near-field excitation amplitude associated with the local density of photonic states. Dispersionless and Drude dispersion models are considered, as well as the effect of interband transitions. Simple formulas are presented to obtain a maximal SP field at a given distance from a canonical source. Examples are shown for graphene and thin metal films, and a discussion of the competition between propagation loss and SP excitation is provided.