Surface-enhanced fluorescence of a dye-doped polymer layer with plasmonic band edge tuning

We investigated experimentally the influence of 1D rectangular Au gratings on fluorescence. The formation of a bandgap in the dispersion relation is confirmed by our experiment. At the edge of this bandgap, the fluorescence of the dye can be strongly enhanced due to the surface plasmon polaritons' large density of states. By structural design we tuned the plasmonic band edges to the wavelength of the fluorescence of the dye molecules. An optimized Au grating structure with a duty ratio of 3/4 is found to achieve up to 120 times stronger fluorescence than that of a planar metal surface.