Date of Award
Physics and Astronomy
Mark Siemens, Ph.D.
We theoretically and experimentally investigate the transfer of orbital angular momentum from light to an ensemble of semiconductor-based nanostructures composed of lead sulfide quantum dots. Using an ensemble of quantum dots offers a higher cross-section and more absorption of twisted light fields compared to experimentally challenging single-nanostructure measurements. However, each quantum dot (except for on-center) sees a displaced light beam parallel to its own axis of symmetry. The transition matrix elements for the light-matter interaction are calculated by expressing the displaced light beam in terms of the appropriate light field centered on the nanoparticles. The resulting transition rate induced by light's orbital angular momentum depends on the nanostructure size, the displacement between the beam center and nanostructure axis, and the ratio of the nanostructure size to the beam waist. In addition, while the strength of the transitions induced by twisted light is much weaker than those induced by plane waves for the center case, they are almost identical when conceding illuminating an ensemble of nanostructures. Although we attempted to measure this transfer of orbital angular momentum, due to experimental limitations the transfer remained undetectable.
Bahamran, Alaa A., "Coupling of Light's Orbital Angular Momentum to a Quantum Dot Ensemble" (2019). Electronic Theses and Dissertations. 1548.
Received from ProQuest
Alaa A. Bahamran
Materials Science, Condensed matter physics