Nanofocusing in a metal-insulator-metal gap plasmon waveguide with a three-dimensional linear taper

Hyuck Choo, Myung Ki Kim, Matteo Staffaroni, Tae Joon Seok, Jeffrey Bokor, Stefano Cabrini, P. James Schuck, Ming C. Wu, Eli Yablonovitch

Research output: Contribution to journalArticlepeer-review

307 Citations (Scopus)


The development of techniques for efficiently confining photons on the deep sub-wavelength spatial scale will revolutionize scientific research and engineering practices. The efficient coupling of light into extremely small nanofocusing devices has been a major challenge in on-chip nanophotonics because of the need to overcome various loss mechanisms and the on-chip nanofabrication challenges. Here, we demonstrate experimentally the achievement of highly efficient nanofocusing in an Au-SiO 2 -Au gap plasmon waveguide using a carefully engineered three-dimensional taper. The dimensions of the SiO 2 layer, perpendicular to the direction of wave propagation, taper linearly below 100 nm. Our simulations suggest that the three-dimensional linear-tapering approach could focus 830 nm light into a 2 × 5 nm 2 area with ≤3 dB loss and an intensity enhancement of 3.0 × 10 4. In a two-photon luminescence measurement, our device achieved an intensity enhancement of 400 within a 14 × 80 nm 2 area, and a transmittance of 74%.

Original languageEnglish
Pages (from-to)838-844
Number of pages7
JournalNature Photonics
Issue number12
Publication statusPublished - 2012 Dec
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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