Fluorescence enhancement of quantum dots enclosed in Au nanopockets with subwavelength aperture

The authors observed strong fluorescence (FL) enhancement from CdSe quantum dots (QDs) partially encapsulated in a smooth Au film with subwavelength apertures. So far, the fluorescence of QDs placed on smooth metallic surfaces has been mostly quenched unless the surface was roughened in nanoscale. The pocketed QD FL emitted through the nanoaperture exhibited up to fivefold enhancement when compared with those from QDs on plain Au or glass surfaces. The enhancement depends strongly on the film thickness and becomes maximized at 50 nm. This study shows that the dependence may be closely related to the surface plasmon-polariton characteristics of the Au layer.