Abstract
Optical trapping of metallic nanoparticles investigates phenomena at the interface of plasmonics and optical micromanipulation. This thesis combines ideas from the optical properties of metals, originating in solid-state physics, with the force mechanisms resulting from optical trapping. I explore the influence of enhanced light-matter interaction due to the plasmon resonances of gold particles on their trapping properties. I present theories for trapping mechanisms of gold metallic particles and then verify these theories through experiments. Optical trapping of metallic nanoparticles is considered challenging, especially in air, as they are highly absorbing and reflecting at optical wavelengths. Yet the optical levitation of these particles provides an excellent tool to investigate their plasmonic properties away from any interface and offers opportunities to explore interaction processes between light and particles. The optical and thermal forces acting on the particle depend on their microscopic optical and thermal properties. These parameters vary drastically around the plasmon resonance, thus not only changing the magnitude but also the direction and entire nature of the acting forces. So far, optical trapping of metallic particles has focused on wavelengths far from the particle's resonance in the infrared, and on liquids rather than air. In this thesis, I concentrate on optical trapping of gold micro and nanoparticles, expanding the knowledge of metallic nanoparticle trapping available to date. In Mie regime, I present both the theory and experiment of a trapping scheme based on dynamic potential manipulation that is capable of trapping gold microparticles in air for more than one hour. In the dipole regime, I present a theory based on nonlinear optical trapping which opens new insights in the field of levitated optomechanics. For the first time, I show that two-photon absorption is the reason for the longitudinal stability of gold nanoparticles. This theory correctly addresses the effect of four-wave mixing and two-photon absorption on the behavior of the trapping system.
Degree
MS
College and Department
Ira A. Fulton College of Engineering; Electrical and Computer Engineering
Rights
https://lib.byu.edu/about/copyright/
BYU ScholarsArchive Citation
Mirzaei Ghormish, Siavash, "Advancements in Levitated Optomechanics: Exploring Plasmon-Enhanced Light-Matter Interactions in Optical Trapping" (2023). Theses and Dissertations. 10617.
https://scholarsarchive.byu.edu/etd/10617
Date Submitted
2023-12-07
Document Type
Thesis
Handle
http://hdl.lib.byu.edu/1877/etd13454
Keywords
levitated optomechanics, plasmonic, linear optical trapping, nonlinear optical trapping
Language
english