Improving the excitation efficiency of Surface Plasmon Polaritons near small apertures in metallic films
department or school: Applied Science, Faculty of
department or school: Engineering, School of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Mehfuz, Reyad
issued: 2013-11-29T17:00:42Z
issued: 2013
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Light incident onto a small aperture in a metal film can convert into light waves bound to the surface of that film. At visible frequencies and beyond, these surface-bound waves are commonly known as surface plasmon polaritons (SPPs). In this work, we explore ways to enhance the excitation efficiency of SPPs in the vicinity of a slit aperture. We introduce a basic method to treat this problem in which the slit and adjacent metal surface are approximated as independent waveguides. By mapping out the electromagnetic modes sustained by the waveguide components approximating the slit structure, we predict enhanced SPP excitation efficiency when wave vector matching is achieved between the waveguide modes. The concept of wave vector matching is applied to investigate SPP coupling efficiencies for various slit geometries and material configurations. We consider slits with dimensions comparable to the incident wavelength, categorizing this work into explorations of sub-wavelength and super-wavelength slits. We show that SPP coupling from a sub-wavelength slit can be enhanced by placing a dielectric layer onto the exit side of the metal surface. By varying the layer thickness, it is possible to tune the efficiency of SPP coupling, which can be enhanced significantly (about six times) relative to that without the layer. Broadband enhancement of SPP coupling from a sub-wavelength slit over most of the visible spectrum is also demonstrated using the same method. We also show that high-efficiency SPP coupling can be achieved using a super-wavelength slit. We hypothesize that higher-order modes in a large slit can assist wave vector matching and boost SPP coupling. Enhanced SPP excitation in a slit aperture is first shown using numerical simulations, and later verified with experiments. Overall, the thesis demonstrates that simple wave vector matching conditions, similar to classical SPP coupling methods based on prisms or gratings, can also be applied to describe SPP coupling i…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/45566
note: Improving the Excitation Efficiency ofSurface Plasmon Polaritons NearSmall Apertures in Metallic FilmsbyReyad MehfuzB.Sc., Bangladesh University of Engineering and Technology, 2004M.Sc., International Islamic University Malaysia, 2008A 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 2013c? Reyad Mehfuz, 2013AbstractLight incident onto a small aperture in a metal film can convert intolight waves bound to the surface of that film. At visible frequencies and be-yond, these surface-bound waves are commonly known as surface plasmonpolaritons (SPPs). In this work, we explore ways to enhance the excitationefficiency of SPPs in the vicinity of a slit aperture. We introduce a basicmethod to treat this problem in which the slit and adjacent metal surfaceare approximated as independent waveguides. By mapping out the elec-tromagnetic modes sustained by the waveguide components approximatingthe slit structure, we predict enhanced SPP excitation efficiency when wavevector matching is achieved between the waveguide modes. The concept ofwave vector matching is applied to investigate SPP coupling efficiencies forvarious slit geometries and material configurations. We consider slits withdimensions comparable to the incident wavelength, categorizing this workinto explorations of sub-wavelength and super-wavelength slits. We showthat SPP coupling from a sub-wavelength slit can be enhanced by placing adielectric layer onto the exit side of the metal surface. By varying the layerthickness, it is possible to tune the efficiency of SPP coupling, which can beenhanced significantly (about six times) relative to that without the layer.Broadband enhancement of SPP coupling from a sub-wavelength slit overmost of the visible spectrum is demonstrated using the same method. Wealso show that high-efficiency SPP coupling can be achieved using a…
has type: Thesis/Dissertation
date issued: 2014-05
is shown at: 10.14288/1.0074316
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/2429/45566