Web Release Date: November 14,
Plasmonic Modes of Annular Nanoresonators Imaged by Spectrally Resolved Cathodoluminescence
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Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, California 91125, Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands, Centre National de la Recherche Scientifique, 3 Rue Michel-Ange, 75794 Paris Cedex 16, France, Instituto de Optica, CSIC, Serrano 121, 28006 Madrid, Spain
Received July 23, 2007
Revised October 16, 2007
Abstract:
We report the observation of plasmonic modes of annular resonators in nanofabricated Ag and Au surfaces that are imaged by spectrally resolved cathodoluminescence. A highly focused 30 keV electron beam is used to excite localized surface plasmons that couple to collective resonant modes of the nanoresonators. We demonstrate unprecedented resolution of plasmonic mode excitation and by combining these observations with full-field simulations find that cathodoluminescence in plasmonic nanostructures is most efficiently excited at positions corresponding to antinodes in the modal electric field intensity.
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