Boosting Local Field Enhancement by on-Chip Nanofocusing and Impedance-Matched Plasmonic Antennas

Volodymyr Zenin, Andrei Andryieuski, Radu Malureanu, Ilya Radko, Valentyn S. Volkov, Dmitri K. Gramotnev, Andrei V. Lavrinenko, Sergey I. Bozhevolnyi

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Strongly confined surface plasmon-polariton modes can be used for efficiently delivering the electromagnetic energy to nano-sized volumes by reducing the cross sections of propagating modes far beyond the diffraction limit, i.e., by nanofocusing. This process results in significant local-field enhancement that can advantageously be exploited in modern optical nanotechnologies, including signal processing, biochemical sensing, imaging and spectroscopy. Here, we propose, analyze, and experimentally demonstrate on-chip nanofocusing followed by impedance-matched nanowire antenna excitation in the end-fire geometry at telecom wavelengths. Numerical and experimental evidences of the efficient excitation of dipole and quadrupole (dark) antenna modes are provided, revealing underlying physical mechanisms and analogies with the operation of plane-wave Fabry-Pérot interferometers. The unique combination of efficient nanofocusing and nanoantenna resonant excitation realized in our experiments offers a major boost to the field intensity enhancement up to ~12000, with the enhanced field being evenly distributed over the gap volume of 30×30×10 nm3, and promises thereby a variety of useful on-chip functionalities within sensing, nonlinear spectroscopy and signal processing.
Original languageEnglish
JournalNano Letters
Volume15
Issue number12
Pages (from-to)8148-8154
ISSN1530-6984
DOIs
Publication statusPublished - 9. Nov 2015

Keywords

  • Surface plasmons polaritons
  • phase-resolved near-field microscopy
  • optical antennas
  • field enhancement
  • tapered waveguide
  • nanofocusing

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