Effect of surface roughness on metal enhanced fluorescence in planar substrates and optical fibers

Abstract

We investigate the effect of the roughness of thin silver films on the performance of sensors that exploit metal enhanced fluorescence (MEF). Fluorescence enhancement of dye molecules of up to 47 times was observed on planar glass substrates coated with metal films of higher roughness of around 8 nm. We also study the fluorescence enhancement on the rough silver films implemented on a side of an optical fiber and analyze its dependence on the thickness of the metal. A maximum enhancement factor of 15 was demonstrated for thinner coatings where the film could be considered as a layer of particles. The chemical electroless plating technique used here to produce films with desired roughness is a low cost simple alternative to complex procedures that are currently used for fabrication of nanostructured metal coatings on optical fibers for MEF.