Near-field scattered by a single nanoslit in a metal film

Lionel Aigouy (1) , Philippe Lalanne (2) , Haitao Liu (3, 2) , Gwénäelle Julié (4) , Véronique Mathet (4) , Michel Mortier (5)

1 Laboratoire Photons Et Matière
2 Laboratoire Charles Fabry de l'Institut d'Optique / Naphel
3 Key Laboratory of Opto-electronic Information Science and Technology
4 IEF - Institut d'électronique fondamentale
5 LCMCP (site ENSCP) - Laboratoire de Chimie de la Matière Condensée de Paris (site ENSCP)

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 μm) ,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.

Domaines: Optique [physics.optics]

Lionel Aigouy, Philippe Lalanne, Haitao Liu, Gwénäelle Julié, Véronique Mathet, et al.. Near-field scattered by a single nanoslit in a metal film. Applied optics, 2007, 46 (36), pp.8573-8577. ⟨10.1364/AO.46.008573⟩. ⟨hal-00877484⟩