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Improving the Mismatch between Light and Nanoscale Objects with Gold Bowtie Nanoantennas

2005; American Physical Society; Volume: 94; Issue: 1 Linguagem: Inglês

10.1103/physrevlett.94.017402

1092-0145

P. James Schuck, David P. Fromm, Arvind Sundaramurthy, G. S. Kino, W. E. Moerner,

Near-Field Optical Microscopy

Metallic bowtie nanoantennas should provide optical fields that are confined to spatial scales far below the diffraction limit. To improve the mismatch between optical wavelengths and nanoscale objects, we have lithographically fabricated Au bowties with lengths approximately 75 nm and gaps of tens of nm. Using two-photon-excited photoluminescence of Au, the local intensity enhancement factor relative to that for the incident diffraction-limited beam has been experimentally determined for the first time. Enhancements >10(3) occur for 20 nm gap bowties, in good agreement with theoretical simulations.