| Description |
Metallic nanostructures have been studied for their ability to support surface plasmons, the collective oscillations of conduction band electrons, which provides numerous ways to control and manipulate light at the nanoscale. Highly confined resonance with field enhancement can be achieved and readily tuned by manipulation of the nanostructure shape, texture, and material composition. However, extending the plasmonics response into the ultraviolet (UV) has encountered significant challenges in both engineering (nanostructure design, optimization, and fabrication) and materials science (detailed composition analysis). Therefore, motivated by its tremendous potential in the biochemistry and photochemical applications, this dissertation focus on fostering the advancement of UV plasmonics in terms of metallic nanostructure design, fabrication, and material characterization. The first portion of this dissertation contains an introduction to the basics underlying the electromagnetic (EM) field enhancement and spatial confinement inside the plasmonic nanostructure. The challenges based upon material optical properties in the UV to strong plasmonics response is specified, following the numerous applications in critical fields. The second portion evaluates the plasmonic material properties aluminum (Al) and magnesium (Mg), and the use of these materials in common plasmonic nanostructures. The Extraordinary Optical Transmission (EOT) through Al and Mg nanohole array is compared and the impact of Focused Ion Beam (FIB) lithography method is qualitatively analyzed based on the sample elemental analysis. Al turns out to be the most applicable plasmonic metal in the UV even compared with Mg. Focusing on Al, the following three chapters propose four other plasmonic nanostructures to achieve UV nanofocusing - the V-groove geometry, nanocrescent antenna array coupled to a ground plane, and two variations on a 3D nanocavity antenna array. Engineering methology is discussed for plasmonic nanostructure design, optimization, and fabrication that results in significant enhancement of the resonance field by factors greater than 100. This research work has explored multiple plasmonic nanostructure geometries as well as the material optical responses in the UV to visible region. Methods of simulation design, nanofabrication technology, material characterization, the extinction and fluorescence measurement are provided or improved to fulfill the promising plasmonic applications in the UV. |
