Enhancement of Resonant Energy Transfer Due to Evanescent-wave from the Metal

The high density of evanescent modes in the vicinity of a metal leads to enhancement of the near-field F\"{o}rster resonant energy transfer (FRET) rate. We present a classical approach to calculate the FRET rate based on the dyadic Green's function of an arbitrary dielectric environment, and consider non-local limit of material permittivity in case of metallic halfspace and thin film. In a dimer system, we find that the FRET rate is enhanced due to shared evanescent photon modes bridging a donor and an acceptor. Furthermore, a general expression for the FRET rate for multimer systems is derived. The presence of a dielectric environment and the path interference effect enhance the transfer rate, depending on the combination of distance and geometry.