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

Choo, Hyuck and Kim, Myung-Ki and Staffaroni, Matteo and Seok, Tae Joon and Bokor, Jeffrey and Cabrini, Stefano and Schuck, P. James and Wu, Ming C. and Yablonovitch, Eli (2012) Nanofocusing in a metal–insulator–metal gap plasmon waveguide with a three-dimensional linear taper. Nature Photonics, 6 (12). pp. 838-844. ISSN 1749-4885.

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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%.

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Additional Information:© 2012 Nature Publishing Group, a division of Macmillan Publishers Limited. Received 17 April 2012; accepted 10 October 2012; published online 18 November 2012. The authors thank X. Meng for gold evaporation and J. Dionne for her continuous encouragement. This work was supported by the Defense Advanced Research Project Agency (DARPA) Science & Technology (S&T) Surface-Enhanced Raman Scattering (SERS) programme, the Department of Energy (DOE), and the Engineering and Applied Sciences (EAS) division of California Institute of Technology. Author contributions: H.C. fabricated the 3D NPC devices, performed the experiments, and carried out TPPL measurements. S.C. and P.J.S. assisted with device fabrication and measurement collection. M.K. conducted the simulations and, with H.C., analysed the experimental data. M.S. and T.J.S. assisted with the simulations. J.B., M.W. and E.Y. provided in-depth discussion of the project. H.C. and M.K. wrote the manuscript.
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Defense Advanced Research Projects Agency (DARPA) UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Caltech Engineering and Applied Sciences (EAS) DivisionUNSPECIFIED
Subject Keywords:Plasmonics; Nanophotonics
Record Number:CaltechAUTHORS:20130115-155958768
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36408
Deposited By: Jason Perez
Deposited On:16 Jan 2013 23:39
Last Modified:23 Mar 2015 20:57

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