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Singular Fluctuational Electrodynamic Effects in Hyperbolic Metamaterials and Moving Media

  • Author / Creator
    Guo, Yu
  • Metamaterials are artificial media designed to achieve exotic electromagnetic responses that are not available in conventional materials. Engineering the black body thermal emission using metamaterials promises to impact a variety of applications involving thermophotovoltaics, energy management and coherent thermal sources. Metamaterials with hyperbolic dispersion exhibit a broadband singularity in the bulk photonic density of states, which can be thermally excited and utilized in various thermal applications. In this report, we give a detailed account of equilibrium and non-equilibrium fluctuational electrodynamics of hyperbolic metamaterials. We show the unifying aspects of two different approaches; one utilizes the second kind of fluctuation dissipation theorem and the other makes use of the scattering method. We show the existence of broadband thermal emission and heat transfer beyond the black body limit in the near field. This arises due to the thermal excitation of unique bulk metamaterial modes, which do not occur in conventional media. We analyze the near-field of hyperbolic metamaterials at finite temperatures and show that the lack of spatial coherence can be attributed to the multi-modal nature of super-Planckian thermal emission. We also adopt the analysis to phonon-polaritonic super-lattice metamaterials and describe the regimes suitable for experimental verification of our predicted effects. The results also reveal that far-field thermal emission spectra are dominated by epsilon-near-zero and epsilon-near-pole responses as expected from Kirchoff's laws. Our work should aid both theorists and experimentalists to study complex media and engineer equilibrium and non-equilibrium fluctuations for applications in thermal photonics. In the second part, we describe our discovery of a singular resonance with infinite quality factor which occurs between moving plates. Conventional resonators fold the path of light by reflections leading to a phase balance and thus constructive addition of propagating waves. However, amplitude decrease of these waves due to incomplete reflection or material absorption leads to a finite quality factor of all resonances. Here we report on our result that evanescent waves can lead to both a phase and amplitude balance causing an ideal and Fabry-Perot resonance condition in spite of material absorption and non-ideal boundary discontinuities. The counterintuitive resonance occurs if and only if the Fabry-Perot plates are in relative motion to each other separated by a critical distance. We show that this singular resonance can be thermally excited between moving plates separated by a small gap causing a large number of photons to be exchanged between them. Furthermore, we also show that this resonance fundamentally dominates all non-equilibrium interactions (momentum and heat transfer) between the moving bodies. Our result is valid in the relativistic limit considering polarization mixing and also reveals the important role of the singular resonance on the fluctuational drag force between moving bodies in the T$ o$0 limit (quantum friction).

  • Subjects / Keywords
  • Graduation date
    2014-11
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/R30H35
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Master's
  • Department
    • Department of Electrical and Computer Engineering
  • Specialization
    • photonics and plasmas
  • Supervisor / co-supervisor and their department(s)
    • Jacob, Zubin (Department of Electrical and Computer Engineering)
  • Examining committee members and their departments
    • Jacob, Zubin (Department of Electrical and Computer Engineering)
    • Page, Don (Department of Physics)
    • Tsui, Ying (Department of Electrical and Computer Engineering)