recent research work

Now it’s made available online : D. Gerard et al, Phys Rev B 77, 045413 (2008)

Briefly, we experimentally compare the properties of circular nanoapertures milled in gold and aluminium to enhance the fluorescence of dyes diffusing within the nanoapertures. Our main result is that nanoapertures in gold exhibit much higher fluorescence enhancement. We discuss the influence of a noble metal holding plasmonic resonances in the visible range such as gold. Altogether, these results provide crucial knowledge for the design of nanoapertures towards high-efficiency single-molecule analysis.

As an interdisciplinary project for students of the Ecole Centrale Marseille, a joint team with my lab developed a demonstration version of a trinocular microscope. The aim is to introduce students to the principles of image formation, Fourier optics, and basic contrast filtering techniques in microscopy.  This work follows a pioneering demonstration by Peter Evenett (Leeds, UK).

Two USB video cameras are used: the first one observes the image of the sample, the second is conjugated to the microscope objective’s back focal plane (Fourier plane). This allows a simultaneous monitoring of both direct and Fourier images.

As an example, the following picture shows the direct (left) and Fourier (right) images of gratings with two different pitches. Smaller pitches yield farer diffracted orders in Fourier space.

Different kind of filters can be set into the Fourier plane, direct observation on their influence on image formation can be inferred. In the following, a black mask is set in the back focal plane to suppress the central (non-diffracted) order. Only the first (plus and minus) diffracted orders are transmitted and contribute to the final image, giving a crisper contrast.

Best wishes

The Mosaic group at the Institut Fresnel offers training periods for graduate students in optics and photonics. PhD positions are also available based on the different internship subjects, depending on the applicant’s profile and fundings (read more about this topic in my previous post here). More information can be found on the MOSAIC website.

I would like to give a special emphasis to the subject I propose following this link:

http://www.fresnel.fr/mosaic/jobs/pdf_files/Nanoapertures%20JW.pdf

The 3-years ANTARES project aims at fabricating and characterizing nanostructured substrates for surface enhanced Raman scattering (SERS) and fluorescence emission. The controlled arrangement of the colloidal structure and the use of single crystal colloids will enable to adapt the optical specifications in terms of spectral response and electromagnetic enhancement.

Learn more at http://icb.u-bourgogne.fr/antares/