In this thesis, we will discuss the possibility of wave manipulation by graded materials and/or systems. In contrast to the traditional inhomogeneous media, i.e. periodically modulated system and randomly disordered system, graded system demonstrates a unique way to control wave, resulting in a new type of localization-delocalization transition, which can confine the primary excitations (e.g., photons, phonons, and surface plasmons) and redistribute them spatially. This is not only of fundamental significance, but will also pave new avenue for various applications, for example, in surface elastic waves, nanooptics, and plasmonics. It also has implications with practical problems in industry such as oil probing and earthquake study. / Manipulating waves (e.g., elastic or electromagnetic) inside nanostructures has attracted ever increasing interest over the past decades due to the rapid advancement of nanofabrication techniques. Particularly, interactions of light with structures modulated at the wavelength or subwavelength scale offer an opportunity to achieve novel properties and designated functionalities in nanophotonics. Notable examples include photonic crystals, various metamaterials, and plasmonic devices. / Moreover, we consider to combine the novel properties of gradons and surface plasmons (SPs), in an attempt to explore new mechanisms to manipulate SP. Firstly, we study an incrementally-spaced nanoparticle chain waveguide, in which coupled plasmon waves show a localization-delocalization transition, in analogy to the elastic gradons. Secondly, we propose waveguides using periodic plasmonic chains immersed in a graded host which can sustain "light", "heavy", and "light-heavy" plasmonic gradons. Existence of tunable passband is demonstrated in these systems. / Thus, in view of the success, we discuss many potential applications in plasmonics, such as junctions, transistors, and even on-chip integrated plasmonic-dielectric devices. In this regard, we further study the most commonly used coplanar photonic elements, i.e., ring resonators and their integrated devices. To explore the interactions between various gradons and typical excitations would be very interesting and rewarding. Our findings have important ramifications for understanding excitations with transition spectra in many condensed matter systems, ranging from ultrasonic waves, seismic waves to light waves, microwaves, as well as quantum waves. / We started with one-dimensional graded networks of coupled harmonic oscillators. By examining the vibrational mode characteristics, we have identified a new kind of vibrational excitations, which are named "gradons". The features of elastic gradon are elab orated. Gradon localization is also different from well-known mechanisms of localization transition, such as defect(s) and Anderson-type localization. Gradons in higher dimensional graded elastic networks show more intriguing behaviors; we proved the existence of "soft", "hard", and "soft-hard" gradons in two dimensional cases. / Xiao Junjun = 新型调波功能材料 : 梯度子及其在纳米光学中的应用 / 肖君军. / "May 2006." / Adviser: Kin Wah Yu. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1694. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 108-118). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307. / Xiao Junjun = Xin xing diao bo gong neng cai liao : ti du zi ji qi zai na mi guang xue zhong de ying yong / Xiao Junjun.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_343892 |
| Date | January 2006 |
| Contributors | Xiao, Junjun., Chinese University of Hong Kong Graduate School. Division of Physics. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xvii, 124 p. : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
Page generated in 0.0014 seconds