Articles récents

Photonic engineering of fluorescent dyes

9 Janvier 2013 , Rédigé par JW Publié dans #Recent research work

The development of bright water-soluble luminescent probes is a ubiquitous problem in imaging and sensing applications. Designing fluorescent dyes typically relies on a molecular engineering approach in which photophysical properties are tuned by chemical modifications. In a letter published in Angewandte Chemie, we present a novel way of engineering luminescence by changing the photonic environment of a chromophore while maintaining its solubility. This has remained a challenge since the pioneering of this field in the 1970s, mainly because the photonic approach requires combining, in a single hybrid nanostructure, a luminescent molecule and an optical cavity that confines the electromagnetic field.

We solve this challenge by producing purified suspensions of gold nanoparticle dimers linked by a single DNA double strand exhibiting one a single dye molecule. Tuning the electromagnetic field enables unprecedented photophysical properties, such as decay rates and excitation cross-sections enhanced by more than one order of magnitude compared to an optimized, commercial chromophore.

Free access alternative pdf version of the letter can be found via arXiv:1210.6790

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Happy New Research 2013

7 Janvier 2013 , Rédigé par JW Publié dans #Fancy lab

2013-copie-3

Background-free optical fiber probe for Raman spectroscopy

12 Novembre 2012 , Rédigé par JW Publié dans #Recent research work

Optical fiber probes are generating a large interest for portable Raman spectrometers. However, the use of conventional fibers is severely limited by the high luminescence background generated in the silica, which complicates the signal processing and/or the probe implementation.
We solve this issue in a recent article published in Optics Letters by using a new type of hollow core photonic crystal fiber probe for Raman spectroscopy and endoscopy. Thanks to a design based on a large pitch Kagome lattice, the transmission range spans over 150nm, enabling both the excitation and Raman beams to be counter-propagating through the same fiber.
Compared to earlier work, our approach combines several novel key features: (i) the very simple optical configuration, (ii) the two orders of magnitude reduction in silica background noise, and (iii) the large spectral bandwidth for Raman shifts.
http://www.fresnel.fr/spip/spip.php?action=acceder_document&arg=1313&cle=4dfb9d50d3a9bae241d8f92abcf8c666&file=jpg%2Ffiber5.jpg

Science festival 2012

15 Octobre 2012 , Rédigé par JW Publié dans #Fancy lab

Petru and Jerome made the show during Marseille's science festival 2012. About 400 people could discover several optics experiments:

  • seeing stress in plastics
  • origin of the blue color of butterfly wings
  • the schweppes luminescence
  • high rate internet with lasers and fibers

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PhD thesis award Aix Marseille Universite

12 Octobre 2012 , Rédigé par JW Publié dans #Fancy lab

Former co-worker Heykel Aouani has been awarded the 2012 PhD thesis prize of Aix Marseille University, which is ranked #4 among French universities according to Shanghai academic ranking.

Congratulations Heykel !

http://www.fresnel.fr/spip/images/175x225/heykel.aouani.jpg http://upload.wikimedia.org/wikipedia/fr/b/b9/Lofo_Aix-Marseille_Universit%C3%A9.png