Europhys. Lett.
Volume 66, Number 1, April 2004
Page(s) 41 - 47
Section Electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics
Published online 01 March 2004
Europhys. Lett., 66 (1) , pp. 41-47 (2004)
DOI: 10.1209/epl/i2003-10138-7

The optical near-field of an aperture tip

A. Drezet, M. J. Nasse, S. Huant and J. C. Woehl

Laboratoire de Spectrométrie Physique, Université Joseph Fourier Grenoble et CNRS 38402 Saint Martin d'Hères, France

(Received 18 September 2003; accepted in final form 16 January 2004)

We use fluorescent nanospheres as scalar detectors for the electric-field intensity in order to probe the near-field of an optical tip used in aperture-type near-field scanning optical microscopy (NSOM). Surprisingly, the recorded fluorescence images show two intensity lobes if the sphere diameter is smaller than the aperture diameter, as expected only in the case of vector detectors like single molecules. We present a simple but realistic, analytical model for the electric field created by light emitted from a NSOM tip which is in quantitative agreement with the experimental data.

42.25.Fx - Diffraction and scattering.
07.79.Fc - Near-field scanning optical microscopes.
33.50.-j - Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion).

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