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.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-C1-015-21
Acknowledgements: This article was supported by the Center for Advanced Molecular Photovoltaics (award no. KUS-C1-015-21), made by King Abdullah University of Science and Technology (KAUST). The authors also acknowledge support from the Department of Energy (grant DE-FG02-07ER46426) for the realization of the platform and a pilot project of the Center for Cancer Nanotechnology Excellence and Translation (CCNE-T) at Stanford to use this platform to characterize and improve optical antennas for surface-enhanced Raman spectroscopy.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.