Near-field scattered by a single nanoslit in a metal film.
Using a scanning near-field optical microscope, we visualize, in three dimensions, the electromagnetic field distribution near an isolated slit aperture in a thin gold film. At the metal-air interface and for a TM incident polarization, we confirm some recently observed results and show that the slit generates two kinds of surface waves: a slowly decaying surface plasmon polariton and a quasi-cylindrical wave that decreases more rapidly when moving away from the slit. These waves are not generated for a TE incident polarization. In a noncontact mode, we also observe how the transmitted light diverges in free space. At a small distance from the slit (< 2 microm), we find that the emerging light spreads in all directions for TM, forming an electromagnetic cloud, whereas it is concentrated above the slit for TE, forming a more directive light jet. The experimental images are in good agreement with the numerical simulations.
Aigouy
Lionel
L
Laboratoire Photons Et Matière, UPR CNRS A0005, Ecole Supérieure de Physique et de Chimie Industrielles (ESPCI), 10 rue Vauquelin, 75231 Paris Cedex 5, France. aigouy@optique.espci.fr
Lalanne
Philippe
P
Liu
Haitao
H
Julié
Gwénaelle
G
Mathet
Véronique
V
Mortier
Michel
M