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. , ...Daha Fazla

OPTICA, cilt.3, ss.339-346, 2016 (SCI İndekslerine Giren Dergi) identifier

  • Cilt numarası: 3 Konu: 3
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1364/optica.3.000339
  • Dergi Adı: OPTICA
  • Sayfa Sayıları: ss.339-346

Özet

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