recent research work

Our latest paper has been published in the July issue of the Journal of the Optical Society of America B. Free reprints for personal use only are available on our group website here.

In this manuscript, we investigate the interaction between a dipolar emitter and a dielectric microsphere under focused laser illumination. We present a detailed experimental analysis of the fluorescence emission characteristics, and relate our observations to numerical simulations.

Our findings demonstrate that the microsphere acts as a microlens placed in the emitter's near-field, allowing a more efficient focusing of the incident beam as well as increasing the collection of the fluorescence light up to 60% of the total emission. That last figure is more than all the emission normally emitted in the half-space towards the detectors.

This simple scheme outperforms the classical diffraction-limited detection of fluorescent particles, and opens new opportunities for low-cost and highly parallel single-molecule investigations.

Published in the International Journal of Materials and Product Technology, in a special issue on nanostructured materials for photonics applications :

Biophotonics applications of nanometric apertures

Jerome Wenger, Davy Gerard, Pierre-Francois Lenne, Herve Rigneault, Nicolas Bonod, Evgeny Popov, Didier Marguet, Constantin Nelep, Thomas W. Ebbesen

DOI: 10.1504/IJMPT.2009.025002

Actually, this paper was written in March 2007, revised version accepted for publication in September 2007, and finally published in April 2009 !! Never got a decent explanation with such a delay. So this explains why the reference list therein is mostly already obsolete now, with no citations to papers of late 2007 and 2008.

For personal use only, free reprints are available here.

The CNRS Institute of Information and Engineering Sciences and Technologies (INST2I) has highlighted our recent work on photonic nanojets and their use for single molecule detection.

Read more (sorry French only) at : http://www.cnrs.fr/inst2i/recherche/faits-marquants/2009/nanojets-photoniques.htm

Published in Optics Express, freely downloadable at :

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-4-2089

We show that latex microspheres are able to confine light in a three-dimensional region of subwavelength dimensions. A simple configuration, not involving resonances, allows to reach an effective volume as small as 0.6 (lambda/n)^3, hereby beating the far-field diffraction barrier. We relate this phenomenon to interferences between the field scattered by the sphere and the incident Gaussian beam.

The animated gif below shows the electric field intensity distribution while the microsphere is displaced towards the focus of the incident laser beam.

This paper was highlighted as picture of the week on Optics Infobase webpage, and (consequently?) ranked 6^th out of the most downloaded OSA paper of March 2009.

Published in January 15^th issue of Analytical Chemistry :

http://pubs.acs.org/doi/abs/10.1021/ac8024015

The manuscript presents a thorough study of the signal-to-noise improvement in Fluorescence Correlation Spectroscopy (FCS) measurements within a nanoaperture. We believe that this will enable a large variety of new applications of FCS. The paper demonstrates a 10x quality improvement of FCS measurements when using nanoapertures. The graph below shows the quality enhancement of correlation curves for fluorescence molecules in open solution or inside a gold nanoaperture :