Lei Zhu

Graduation Semester and Year




Document Type


Degree Name

Doctor of Philosophy in Electrical Engineering


Electrical Engineering

First Advisor

Michael Vasilyev


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.


Electrical and Computer Engineering | Engineering


Degree granted by The University of Texas at Arlington