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Published September 2008 | public
Journal Article Open

Near-Field Visualization of Strongly Confined Surface Plasmon Polaritons in Metal−Insulator−Metal Waveguides


A nanoscale gap between two metal surfaces can confine propagating surface plasmon polaritons (SPPs) to very small dimensions, but this geometry makes it inherently difficult to image SPP propagation at high resolution. We demonstrate the near-field probing of these SPPs, propagating within a 50 nm thick Si3N4 waveguide with Ag cladding layers for frequencies ranging from the blue to the near-infrared. Using near-field SPP interferometry, we determine the wave vector, showing that the wavelength is shortened to values as small as 156 nm for a free-space wavelength of 532 nm.

Additional Information

© 2008 American Chemical Society. Received June 20, 2008. Web Release Date: August 9, 2008. The authors would like to thank A.F. Koenderink and H. Zeijlemaker for technical assistance. This work was made possible by the fabrication and characterization facilities of the Amsterdam nanoCenter. It is part of the Joint Solar Programme (JSP) of the Stichting voor Fundamenteel Onderzoek der Materie (FOM), which is financially supported by the Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO). The JSP is cofinanced by gebied Chemische Wetenschappen of NWO and Stichting Shell Research. Work at Caltech is financially supported by the Air Force Office of Scientific Research, MURI Grant No. FA9550-04-1-0434. J.A.D. gratefully acknowledges fellowship support from the Department of Defense Army Research Office and the National Science Foundation.


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