Field enhancement in single subwavelength apertures.
A peak of the detected fluorescence rate per molecule has recently been observed in experiments of fluorescence correlation spectroscopy carried out on subwavelength apertures in metallic screens, a phenomenon that appears at a diameter-to-wavelength ratio below the fundamental mode cutoff. Although the origin of the resonant transmission through a subwavelength aperture has been well explained in terms of excitation of plasmon surface modes on the aperture ridge, the origin of the maximum that occurs at a radius-to-wavelength ratio smaller than 1/4 was not clear. Using a rigorous electromagnetic theory of light diffraction in cylindrical geometry, we show that it is linked to the appearance of the fundamental mode propagating inside the aperture. We obtain good agreement between the theoretical and the experimental results.
Popov
Evgeny
E
Institut Fresnel, Domaine Universitaire de Saint Jérôme, Université d'Aix Marseille III, CNRS UMR 6133, 13397 Marseille Cedex 20, France. e.popov@fresnel.fr
Nevière
Michel
M
Wenger
Jérôme
J
Lenne
Pierre-François
PF
Rigneault
Hervé
H
Chaumet
Patric
P
Bonod
Nicolas
N
Dintinger
José
J
Ebbesen
Thomas
T