ELECTROMAGNETIC MODELING OF NANOWIRES AND OPTICAL NANOANTENNAS
Open Access
- Author:
- Rybicki, Brian William
- Graduate Program:
- Electrical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- July 16, 2008
- Committee Members:
- Douglas Henry Werner, Thesis Advisor/Co-Advisor
- Keywords:
- computational electromagnetics
optical antennas
nanowires - Abstract:
- Both the fabrication and placement of nanostructures (i.e. structures whose dimensions are on the order of nanometers) has matured to the point where antenna- and waveguide-like elements may be manufactured and precisely placed into useful configurations. This is of particular interest because it extends conventional antenna concepts and applications into the terahertz and even optical regimes. To support these inquiries, it is necessary to correctly describe the electromagnetic properties with proper modeling. This thesis will address a few specific topics in the modeling of nanoscale electromagnetics and novel applications at terahertz and optical frequencies. First, an analytical treatment of the scattering from GaP nanowires and asymptotic forms of the average internal intensities are derived. The ratio of orthogonally polarized intensities with a vanishingly thin nanowire confirms the presence of the ‘antenna effect’ in this limit. The simulation of arrays of metallic nanowires shows that they may function well as frequency selective surfaces in the mid-infrared. By introducing a small gap in each nanowire, large near fields are produced at resonance that may find use in field enhanced spectroscopy. The excitation of nanowires allows them to function as optical nanoantennas and they are well described by conventional antenna parameters such as input impedance, radiation efficiency and directivity. Nanoantennas can be simulated more efficiently by taking advantage of the surface impedance condition, though with less accurate calculation of the input reactance.