Browsing by Subject "Semiconductors--Optical properties"

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Optical resonators and quantum dots: and excursion into quantum optics, quantum information and photonics
(2007-08) Bianucci, Pablo, 1975-; Shih, Chih-Kang
Modern communications technology has encouraged an intimate connection between Semiconductor Physics and Optics, and this connection shows best in the combination of electron-confining structures with light-confining structures. Semiconductor quantum dots are systems engineered to trap electrons in a mesoscopic scale (the are composed of [approximately] 10000 atoms), resulting in a behavior resembling that of atoms, but much richer. Optical microrseonators are engineered to confine light, increasing its intensity and enabling a much stronger interaction with matter. Their combination opens a myriad of new directions, both in fundamental Physics and in possible applications. This dissertation explores both semiconductor quantum dots and microresonators, through experimental work done with semiconductor quantum dots and microsphere resonators spanning the fields of Quantum Optics, Quantum Information and Photonics; from quantum algorithms to polarization converters. Quantum Optics leads the way, allowing us to understand how to manipulate and measure quantum dots with light and to elucidate the interactions between them and microresonators. In the Quantum Information area, we present a detailed study of the feasibility of excitons in quantum dots to perform quantum computations, including an experimental demonstration of the single-qubit Deutsch-Jozsa algorithm performed in a single semiconductor quantum dot. Our studies in Photonics involve applications of microsphere resonators, which we have learned to fabricate and characterize. We present an elaborate description of the experimental techniques needed to study microspheres, including studies and proof of concept experiments on both ultra-sensitive microsphere sensors and whispering gallery mode polarization converters.
Studies of optical properties of single CdS nanorods
(2003) Kulik, Dmitri; Shih, Chih-Kang
This work describes low-temperature studies of the optical properties of single CdS nanorods in relation to the nanorods’ morphology. Keeping track of the same nanorods in the photoluminescence (PL) study and during the scanning electron microscope (SEM) imaging we were able to distinguish intrinsic spectral features of the nanorods from those of nanocluster aggregates. We observed strong photoluminescence polarization in the direction perpendicular to the nanorods’ axis. The sharp peaks in the “blue” region of the photoluminescence spectra are red-shifted relative to those of the bulk CdS and of the CdS microparticles in the glass matrix. Finally, we observe a very interesting “spectral diffusion” of the main emission peaks with the following characteristics: (a) energy-energy correlation of the two main peaks; (b) Correlation and anticorrelation between energy and intensity for the two peaks. Possible mechanisms behind this phenomenon are discussed.