Doctor of Philosophy
Dr. Mahi R. Singh
This thesis examines optoelectronics of photonic crystals and photonic nanofibers, especially with quantum dots and metallic nanoparticles doped into them. The simulations produced focus on the quantum dots, which are presented in an ensemble of 3-level systems.
In order to consider a photonic nanofiber in isolation, a model was developed for the density of photonic states. We studied two profiles, a square cross-section and a circular cross-section. In addition, we consider two architectures, one where a photonic crystal surrounds a dielectric fiber, and one where the fiber is another photonic crystal. We found several photonic nanofibers with a single bound photonic state and calculated the density of states.
We studied dipole-dipole interactions through photon absorption in three-level quantum dots doped in a photonic nanofiber. The density matrix method was used to calculate the absorption coefficient and the mean field approximation was used to incorporate dipole-dipole interactions. It was found that a transparent state can become an absorbing state if the dipole-dipole interactions are switched on. It is also predicted that one absorbing peak can be split into two absorbing peaks through judicious selection of the resonance energies of the quantum dots and the location of the bound photon state in the nanofiber.
We calculated the energy transfer and photoluminescence in donor and acceptor quantum dots which were embedded in a nonlinear photonic crystal. These quantum dots interacted via the dipole-dipole interaction. It was found that the photoluminescence of the acceptor quantum dot could be controlled by a pump laser.
We have also studied the interactions between a metallic nanosphere and a quantum dot embedded on a dielectric substrate. Dipole-dipole interactions between them caused energy absorption, evaluated with the density matrix method. The absorption spectrum was found to switch from one peak to two peaks when the intensity of the control laser increased. Adding a metallic nanosphere can also cause splitting. Additionally, fluorescence efficiency in the quantum dot was found to be quenched by the presence of the metallic nanosphere.
Finally, we studied quantum coherence and interference phenomena in a quantum dot and metallic nanorod hybrid system. It was predicted that the power absorption spectrum of the metallic nanorod can be switched from two transparent states to one transparent state by the control laser.
These findings can be used to create ultrafast all-optical switching and sensing nanodevices. Also, the systems discussed here have applications in photovoltaics, quantum computation, and cryptography, among others.
Schindel, Daniel G., "The Study of Optoelectronics in Semiconductor and Metallic Nanoparticle Hybrid Systems" (2013). Electronic Thesis and Dissertation Repository. 1136.