Enhanced spontaneous emission in proximity of a plasmonic nano-slit antenna

Abstract

We investigate enhancement in the spontaneous emission (SE) rate of CdSe/ZnS core-shell quantum dots (QDs) by a semi-infinite plasmonic nano-slit antenna. Long Al2O3 filled nano-slits having similar to 15 nm width, similar to 250 nm height, and >50 mu m length in a silver film exhibit strong Fabry-P & eacute;rot like resonances associated with gap plasmon modes. For the QDs located on top or in proximity of the nano-slit, we observe similar to 15 times enhanced SE relaxation rate compared to the free-space environment. The faster relaxation is attributed to Purcell enhancement resulting from the strong field confinement within the nano-slit and the associated increase in the optical density of states. The experimental results are supported by COMSOL simulations. Our findings demonstrate the ability of the plasmonic nano-slit antenna to strongly enhance the SE rate of emitters in proximity.