Fluorescence enhancements and spectral modifications near the cut-off frequency of plasmonic structure

Abstract

The effect of a population of fluorophores coupling to weakly bound surface plasmons in dielectric/metal/dielectric structures is investigated for the purpose of fluorescence enhancement near interfaces and live cell fluorescence surface imaging. We show theoretically and experimentally that for sufficient fluorophore concentrations near such SPP supporting structures significant enhancements in the radiative emission intensity can be observed, with a spectral modification that can be correlated to the average separation of the fluorophores from the substrate. We will discuss the theory behind the effect and some experimental results on imaging labeled proteins in the focal adhesion sites of cells.