Browsing by Author "Ellis, Chase T."

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    Role of epsilon-near-zero substrates in the optical response of plasmonic antennas
    (OPTICAL SOC AMER, 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA, 2016) Kim, Jongbum; Dutta, Aveek; Naik, Gururaj V.; Giles, Alexander J.; Bezares, Francisco J.; Ellis, Chase T.; Tischler, Joseph G.; Mahmoud, Ahmed M.; Caglayan, Humeyra; Glembocki, Orest J.; Kildishev, Alexander V.; Caldwell, Joshua D.; Boltasseva, Alexandra; Engheta, Nader; AGÜ, Mühendislik Fakültesi, Elektrik & Elektronik Mühendisliği Bölümü;
    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