Photocurrent mapping of near-field optical antenna resonances

Edward S. Barnard, Ragip A. Pala, Mark L. Brongersma

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50nm) and wavelength-scale (∼1μm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models. © 2011 Macmillan Publishers Limited. All rights reserved.
Original languageEnglish (US)
Pages (from-to)588-593
Number of pages6
JournalNature Nanotechnology
Issue number9
StatePublished - Aug 21 2011
Externally publishedYes


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