Journal article
Refractive Index-Based Control of Hyperbolic Phonon-Polariton Propagation
Nano letters, Vol.19(11), pp.7725-7734
11/13/2019
DOI: 10.1021/acs.nanolett.9b02651
PMID: 31650843
Abstract
Hyperbolic phonon polaritons (HPhPs) are generated when infrared photons couple to polar optic phonons in anisotropic media, confining long-wavelength light to nanoscale volumes. However, to realize the full potential of HPhPs for infrared optics, it is crucial to understand propagation and loss mechanisms on substrates suitable for applications from waveguiding to infrared sensing. We employ scattering-type scanning near-field optical microscopy (s-SNOM) and nano-Fourier transform infrared (FTIR) spectroscopy, in concert with analytical and numerical calculations, to elucidate HPhP characteristics as a function of the complex substrate dielectric function. We consider propagation on suspended, dielectric and metallic substrates to demonstrate that the thickness-normalized wavevector can be reduced by a factor of 25 simply by changing the substrate from dielectric to metallic behavior. Moreover, by incorporating the imaginary contribution to the dielectric function in lossy materials, the wavevector can be dynamically controlled by small local variations in loss or carrier density. Counterintuitively, higher-order HPhP modes are shown to exhibit the same change in the polariton wavevector as the fundamental mode, despite the drastic differences in the evanescent ranges of these polaritons. However, because polariton refraction is dictated by the fractional change in the wavevector, this still results in significant differences in polariton refraction and reduced sensitivity to substrate-induced losses for the higher-order HPhPs. Such effects may therefore be used to spatially separate hyperbolic modes of different orders and for index-based sensing schemes. Our results advance our understanding of fundamental hyperbolic polariton excitations and their potential for on-chip photonics and planar metasurface optics.
Details
- Title: Subtitle
- Refractive Index-Based Control of Hyperbolic Phonon-Polariton Propagation
- Creators
- Alireza Fali - Department of Physics and Astronomy, University of Georgia, Athens Georgia 30602, United StatesSamuel T. White - Vanderbilt UniversityThomas G. Folland - Vanderbilt UniversityMingze He - Vanderbilt UniversityNeda A. Aghamiri - Department of Physics and Astronomy, University of Georgia, Athens Georgia 30602, United StatesSong Liu - Kansas State UniversityJames H. Edgar - Kansas State UniversityJoshua D. Caldwell - Vanderbilt UniversityRichard F. Haglund - Vanderbilt UniversityYohannes Abate - Department of Physics and Astronomy, University of Georgia, Athens Georgia 30602, United States
- Resource Type
- Journal article
- Publication Details
- Nano letters, Vol.19(11), pp.7725-7734
- DOI
- 10.1021/acs.nanolett.9b02651
- PMID
- 31650843
- NLM abbreviation
- Nano Lett
- ISSN
- 1530-6984
- eISSN
- 1530-6992
- Publisher
- Amer Chemical Soc
- Number of pages
- 10
- Grant note
- N00014-18-12107 / Office of Naval Research CMMI 1538127 / National Science Foundation; National Science Foundation (NSF) FA9559-16-1-0172 / Air Force Office of Scientific Research (AFOSR); United States Department of Defense
- Language
- English
- Date published
- 11/13/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428836302771
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