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Proceedings Paper

Fluorescence enhancement using Fano-resonant a plasmonic nanostructure with selective functionalization of molecules at the electromagnetic hot spot (Presentation Recording)

Paper Abstract

In recent years, one has paid significant attention to plasmonic nanostructures due to their potential for practical applications. Especially, in most plasmonic nanostructures, the local density of optical states is strongly enhanced and confined in the nanogap region – like for example in plasmonic antennas – which results in the so-called electromagnetic hot spots. In this work, we use 4-nanorod structures made with silver to generate and tune Fano resonances exhibiting an asymmetric and narrow lineshape. In such a system, a strongly enhanced electromagnetic field is created in the nanogap when the two antenna modes undergo destructive interference, i.e. at the Fano resonance. The local near field is thus strongly enhanced since most of the energy is not radiated into the far field at that wavelength. We will show that using a 4-nanorod structure in silver, we can easily tune the Fano resonance through the fluorescence spectrum of the molecule under study, thus exploring the different resonance conditions between the molecule absorption/emission bands and the plasmonic nanostructure; both the excitation and emission rates of the molecule can be enhanced when it is placed within the hot spot. To this end, we have developed a double electron beam lithography process to fabricate the plasmonic nanostructures and then selectively immobilize the molecule in the hot spot, in order to investigate the fluorescence enhancement under well-controlled conditions. The fluorescence enhancement is demonstrated by measuring the fluorescence lifetime and the fluorescence count rate. The experimental results are supported by theoretical modelling and numerical calculations with the Green’s tensor method.

Paper Details

Date Published: 5 October 2015
PDF: 1 pages
Proc. SPIE 9547, Plasmonics: Metallic Nanostructures and Their Optical Properties XIII, 95470V (5 October 2015); doi: 10.1117/12.2188226
Show Author Affiliations
Xiaolong Wang, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Olivier J. F. Martin, Ecole Polytechnique Fédérale de Lausanne (Switzerland)

Published in SPIE Proceedings Vol. 9547:
Plasmonics: Metallic Nanostructures and Their Optical Properties XIII
Allan D. Boardman; Din Ping Tsai, Editor(s)

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