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Field enhancement in single subwavelength apertures
Evgeny Popov1, Michel Nevière, Jérôme Wenger
1Institut Fresnel, Domaine Universitaire de Saint Jérôme, Université d'Aix Marseille III, CNRS UMR 6133, 13397 Marseille Cedex 20, France. e.popov@fresnel.fr
Summary
Researchers observed a fluorescence rate peak in subwavelength apertures, unexplained until now. A new electromagnetic theory reveals this peak is due to the fundamental mode propagating within the aperture, matching experimental data.
Area of Science:
- Optics and Photonics
- Plasmonics
- Nanophotonics
Background:
- Fluorescence correlation spectroscopy (FCS) experiments on subwavelength apertures show a fluorescence rate peak.
- This phenomenon occurs below the fundamental mode cutoff diameter-to-wavelength ratio.
- Previous explanations focused on plasmon surface modes, leaving the peak origin unclear.
Purpose of the Study:
- To elucidate the origin of the fluorescence rate peak observed in subwavelength apertures.
- To investigate the role of the fundamental mode in resonant transmission.
- To provide a theoretical explanation for experimental observations.
Main Methods:
- Rigorous electromagnetic theory of light diffraction.
- Analysis in cylindrical geometry.
- Comparison of theoretical predictions with experimental results.
Main Results:
- The fluorescence rate peak is linked to the appearance of the fundamental mode propagating inside the aperture.
- Theoretical calculations show good agreement with experimental data.
- The study clarifies the physics behind resonant transmission below the cutoff ratio.
Conclusions:
- The fundamental mode's propagation within the subwavelength aperture is responsible for the observed fluorescence peak.
- The developed electromagnetic theory accurately describes the phenomenon.
- This work advances the understanding of light interaction with nanostructures.