Surface phonon polaritons coupled to the far-field by a grating at high temperature
Hafeli, Andrew K.
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https://hdl.handle.net/2142/24178
Description
Title
Surface phonon polaritons coupled to the far-field by a grating at high temperature
Author(s)
Hafeli, Andrew K.
Issue Date
2011-05-25T15:02:55Z
Director of Research (if dissertation) or Advisor (if thesis)
Cahill, David G.
Department of Study
Materials Science & Engineerng
Discipline
Materials Science & Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
quartz
polaritons
surface phonons
diffraction gratings
Abstract
This thesis explores surface phonon polaritons (SPhP) in quartz coupled to the far field by gratings, and the temperature dependence of SPhP coupled to the far field. The subject of coupling SPhP to the far-field has been studied in the past, but not at high temperature. Devices proposed to control radiative heat transfer using SPhP would benefit from an understanding of SPhP temperature dependence. In this thesis we study the effects of geometric grating parameters to optimize the coupling of SPhP to the far-field. The width of the SPhP reflectivity dip depends on the depth of the grating. We study, for several grating depths, the tempertature dependence of SPhP radiation in the temperature range between 300 K and 800 K. For a grating depth of 280 nm, the width of the reflectivity dip in the temperature range 300 < T < 800 K is comparable to what is expected for the SPhP excitations of a flat surface. For a grating depth of 670 nm, the width of the reflectivity dip increases significantly due to coupling to far-field radiation. For both depths the width of the SPhP reflectivity dip increases with increasing temperature and corresponds to the increase of the bulk transverse optical phonon damping.
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