Enhancement of the Purcell effect for colloidal CdSe/ZnS quantum dots coupled to silver nanowires by a metallic tip

In this study, the Purcell effect for CdSe/ZnS quantum dots emission coupled to a silver nanowire cavity was investigated. We manipulated the interaction between colloidal quantum dots (QDs) and an Ag NW in the presence of a metallic tip. When a metal tip approaches the Ag NW, the Ag surface plasmon mode could be lifted away from the metallic NW so that a low optical loss could still be obtained. This work demonstrates enhancement of the spatial coupling between the plasmonic mode and light sources and reduction in metal Ohmic losses, resulting in an enhanced Purcell effect and coupling efficiency accompanied with increased fluorescence intensity. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729890]