Surface plasmon enhanced fluorescence: self-consistent classical treatment in the quasi-static limit

The problem of enhanced molecular emission in close proximity to dielectric and metallic interfaces is of great importance for many physical and biological applications. Here we present an exact treatment of the problem from the view point of classical electromagnetism. Self-consistent analytical theory of the surface fluorescence enhancement is developed for configurations consisting of an emitter in proximity to core-shell metal-dielectric nanoparticles. The dependence of the fluorescence enhancement on the excitation laser and fluorescence frequencies and distance of the emitter to the nanoparticle interface are studied. The developed theory predicts enhanced fluorescence at intermediate distances as well as emission quenching into non-radiative surface plasmon (SP) modes dominating the response for short distances. The conditions for optimal emission enhancement for two core-shell configurations are determined. The theory can be applied toward analyzes and optimization of various applications related to SP enhance fluorescence spectroscopy.