Active Nanophotonics For Quantum- And Classical-optics Applications

Abstract

This thesis presents theoretical and experimental development of the interaction enhancement between the photon and matter. We propose one single photon emitter by integrating a single CdSe /ZnS quantum dot into a plasmonic nano-cavity. We experimentally observe directional spontaneous emission with angular half-width of about 10 degrees from a single CdSe/ZnS quantum dot positioned in a slit nanoaperture surrounded by periodic corrugations. Aware of the intrinsic loss limitation of single-photon emitter based on plasmonic nano-cavity, we go on to exploit the relationship between the fluorescence decay times of CdSe/ZnS core-shell quantum dots and the refractive index of the surrounding medium. We report measurements of the fluorescence decay times of CdSe/ZnS core-shell quantum dots at the air-dielectric interface for several dielectrics with different refractive indices. The results are in agreement with a simple theory that accounts for the impact of the refractive index on the density of states and magnitude of the vacuum field, as well as for the local-field correction inside the quantum dot. The results suggest that, by embedding the quantum dots into a high-index dielectric material, one can reduce the spontaneous decay time to sub-nanosecond scale while preserving high quantum efficiency. In order to manipulate the nanoparticle, we propose and demonstrate plasmonic optical tweezers fabricated at the tip of a single mode optical fiber. We trap sub-micronsize particles in 3 dimensions by this simple tool.