Doctor of Philosophy Abstract Metallic nanostructures are one of the most versatile tools available for manipulating light at the nanoscale. These nanostructures support surface plasmons, which are collective excitations of the conduction electrons that can exist as propagating waves at a metallic interface or as localized excitations of a nanoparticle or nanostructure. Plasmonic structures can efficiently couple energy from freely propagating electromagnetic waves to localized electromagnetic fields and vice-versa, essentially acting as an optical antenna.
Plasmonic nanostructures and optical metamaterials enable drastic control and manipulation of light at such small scales. However it is quite challenging to further reduce the size of resonant elements using conventional plasmonic nanostructures. In this paper, we propose novel optical resonators that rely on the conducting plasmon mode of touching nanoparticle chains that enable significant size reduction when compared with widely used nanostripe antennas and U-shaped split-ring resonators.
We employ full-field electromagnetic simulations to study the resonance mechanisms of nanoparticle chain arrays. In comparison with the nanobar plasmonic antennas, a nanoparticle chain based antenna with similar physical sizes operates at larger wavelengths, opening routes for deep subwavelength plasmonic resonators.
Similarly, nanoparticle-based split-ring resonators provide significant size reduction that could be used for smaller metamaterial and metasurface building blocks.
Designing nanoparticle-based resonant elements is a promising route for achieving optical metamaterials with smoother resonance dispersion and lower optical losses. AB - The control of light-material interactions at the nanoscale requires optical elements with sizes much smaller than the wavelength of light.
KW - gold nanoparticle.The following chapters of this thesis are broken up into six parts: plasmonic structure design, micro/nanoscale temperature measurements, methods/results, thermal modeling, discussion, and conclusions.
remote ions using a plasmonic antenna is presented. An optical bowtie antenna is designed and simulated using COMSOL Multiphysics R. The method is evaluated by comparison to a theoretical model for a simple case. Simulations show that the designed antenna can enhance an evanescent eld more than times at the surface of a crystal.
These nanoparticles can behave as antennas for optical electromagnetic radiation and can be used to investigate nanoscopic processes by measuring the optical spectral response of individual nanoantennas. In this thesis, original research is presented that expands our knowledge and understanding of how plasmonic nanoantennas respond to.
Title of doctoral thesis: Plasmonic Nanospectrocopy of Individual Nanoparticles Studies of Metal-Hydrogen Interactions and Catalysis Abstract Localized surface plasmon resonance (LSPR) is the phenomenon of collective oscillation of conduction electrons in metal nanoparticles smaller than the wavelength of light used for the excitation.
We have also recently imaged plasmonic hotspots located in the nanogaps of infrared optical antennas in the near-field.
The enhanced evanescent field resonance is shown to depend strongly on excitation wavelength, the excitation and detection laser polarization, and gap size.
UNIVERSITY OF CALIFORNIA. Los Angeles.
Darkfield Imaging with a Plasmonic Focusing Lens: Antenna Theory for. Near-field Scanning Optical Microscopes. A dissertation submitted in partial satisfaction of the.
requirements for the degree Doctor of Philosophy. in Electrical Engineering. by.