Date of Graduation

2014

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Terence D Musho

Committee Co-Chair

Osama Mukdadi

Committee Member

Nick Wu

Abstract

In the recent years, the emergence of electromagnetic metamaterials (MMs) have ushered in an exciting new field with many promising applications in direct energy conversion. One of the more promising applications of MMs is the ability to fully harness the solar energy through the design of a perfect electromagnetic absorber. Electromagnetic MMs posses the ability to manipulate a material's response resulting in augmented properties such as negative index of refraction, artificial permittivity, and permeability. One of the proven methods for the construction of electromagnetic metamaterials is to use a metal-dielectric composite whereby the electromagnetic response is governed by oscillating surface plasmons and the geometry of the dielectric environment. However, the majority of these materials exhibit a peak absorptivity at a single frequency, therefore, a deep understanding of their response becomes necessary to target approaches to broadening the absorptivity.;In this research the reflectance, transmittance, absorbance, and heat generation in a square nano-antenna composed of a metal-dielectric-metal construction was investigated. The wavelength of interest was in the visible regime from 390-700nm (430-790 THz). The dual focus of this research was 1) the development of metamateial with high absorbance characteristics and 2) the development of a broadband response. The focus was on tailoring the particle geometry and dielectric environment. The nano-antenna was constructed from a silver nano-particle situated on top of a controlled thickness aluminium oxide dielectric material followed by a thick silver ground plane. For this study a transverse electric (TE) plane wave was propagated in the negative z direction and the resulting scattered parameters were monitored. In order to evaluate the electromagnetic response (absorbance) at the sub-wavelength scales, a finite-difference time-domain (FDTD) method was implemented. In addition, the interaction from the neighboring particles en route to a perfect broadband absorber was studied. Our simulation results indicate a complex response between neighboring particles that could be categorized into four independent effective interactions. Furthermore, by controlling the distance between particles, the absorptivity achieved an increase by seven fold.

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