Role of epsilon-near-zero substrates in the optical response of plasmonic antennas


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Kim J., Dutta A., Naik G. V. , Giles A. J. , Bezares F. J. , Ellis C. T. , ...More

OPTICA, vol.3, no.3, pp.339-346, 2016 (Journal Indexed in SCI) identifier

  • Publication Type: Article / Article
  • Volume: 3 Issue: 3
  • Publication Date: 2016
  • Doi Number: 10.1364/optica.3.000339
  • Title of Journal : OPTICA
  • Page Numbers: pp.339-346

Abstract

Radiation patterns and the resonance wavelength of a plasmonic antenna are significantly influenced by its local environment, particularly its substrate. Here, we experimentally explore the role of dispersive substrates, such as aluminum-or gallium-doped zinc oxide in the near infrared and 4H-silicon carbide in the mid-infrared, upon Au plasmonic antennas, extending from dielectric to metal-like regimes, crossing through epsilon-near-zero (ENZ) conditions. We demonstrate that the vanishing index of refraction within this transition induces a "slowing down" of the rate of spectral shift for the antenna resonance frequency, resulting in an eventual "pinning" of the resonance near the ENZ frequency. This condition corresponds to a strong backward emission with near-constant phase. By comparing heavily doped semiconductors and undoped, polar dielectric substrates with ENZ conditions in the near- and mid-infrared, respectively, we also demonstrate the generality of the phenomenon using both surface plasmon and phonon polaritons, respectively. Furthermore, we also show that the redirected antenna radiation induces a Fano-like interference and an apparent stimulation of optic phonons within SiC. (C) 2016 Optical Society of America