Investigating spatial-frequency power flow and evanescent-wave amplification in metamaterial superlenses
department or school: Applied Science, Faculty of
department or school: Engineering, School of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Aghanejad, Iman
issued: 2019-11-25T15:15:46Z
issued: 2019
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: It has been shown that a homogeneous and isotropic material with simultaneously negative values of permittivity and permeability exhibits counter-intuitive responses such as refraction to the same side of normal (negative refraction) and evanescent wave amplification. Consequently, a flat slab of this material can focus an object to the image plane and overcome the diffraction limit associated with conventional dielectric lenses. Such double-negative materials do not exist in nature, however, artificial structures comprised of arrays of resonant inclusions have been designed to mimic their responses and realize a flat superlens with sub-diffractive resolution. This thesis rigorously investigates the behaviour of these artificial heterogeneous structures known as negative-index metamaterials. In the first part of this work, we present spatial frequency maps of power flow in order to provide deeper insights into the flow of propagating waves in negative-index metamaterials. We show through k-space diagrams that the distribution of power can vary considerably across these structures. These observations allow us to categorize different metamaterials and identify the mechanism behind negative refraction at a given interface. We also discuss how k-space maps of power flow can be used to explain the high or low transmittance of the power into different superlenses made from negative-index metamaterials. In the second part of this work, we study evanescent wave amplification in negative-index metamaterial lenses and propose design strategies to improve their imaging resolution and robustness. We show how resonant modes arising in metamaterial superlenses cause imaging artifacts and reduce imaging fidelity. We choose a well-studied periodic structure consisting of an array of magnetodielectric cylinders for the lens medium under test. We demonstrate that the presence of these artifacts can lead to erroneous interpretation of the standard two-source resolution test for lenses…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/72395
note: Investigating Spatial-Frequency PowerFlow and Evanescent-WaveAmplification in MetamaterialSuperlensesbyIman AghanejadA THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinThe College of Graduate Studies(Electrical Engineering)THE UNIVERSITY OF BRITISH COLUMBIA(Okanagan)November 2019© Iman Aghanejad, 2019The following individuals certify that they have read, and recommendto the College of Graduate Studies for acceptance, a thesis/dissertation en-titled:Investigating Spatial-Frequency Power Flow and Evanescent-Wave Amplification in Metamaterial Superlensessubmitted by Iman Aghanejad in partial fulfilment of the requirements ofthe degree of Doctor of PhilosophyDr. Lo¨ıc Markley, School of EngineeringSupervisorDr. Kenneth J. Chau, School of EngineeringSupervisorDr. Jonathan F. Holzman, School of EngineeringSupervisory Committee MemberDr. Murray Neuman, School of Arts and SciencesUniversity ExaminerDr. Ma´rio G. Silveirinha, Department of Electrical and Computer Engineering, University of LisbonExternal ExamineriiAbstractIt has been shown that a homogeneous and isotropic material with simul-taneously negative values of permittivity and permeability exhibits counter-intuitive responses such as refraction to the same side of normal (negativerefraction) and evanescent wave amplification. Consequently, a flat slabof this material can focus an object to the image plane and overcome thediffraction limit associated with conventional dielectric lenses. Such double-negative materials do not exist in nature, however, artificial structures com-prised of arrays of resonant inclusions have been designed to mimic theirresponses and realize a flat superlens with sub-diffractive resolution. Thisthesis rigorously investigates the behaviour of these artificial heterogeneousstructures known as negative-index metamaterials.In the first part of this work, we present spatial frequency maps of powerflow in order to provide deeper insights into the …
has type: Thesis/Dissertation
date issued: 2020-05
is shown at: 10.14288/1.0385859
language: eng
degree discipline: Electrical Engineering
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/72395