Yannick Petit
University of Bordeaux
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Publication
Featured researches published by Yannick Petit.
Optical Materials Express | 2011
Arnaud Royon; Yannick Petit; Gautier Papon; Martin Richardson; Lionel Canioni
This article deals with the recent advances in photochemistry in optical materials induced by femtosecond laser pulses. The field of investigation of this paper is limited to bulk solid isotropic transparent materials (glasses and polymers), specifically tailored with photoactive agents. The formation mechanisms of laser-induced color centers, nanoclusters, nanoparticles and nanocrystallites are reviewed and argued, in particular the influence of the temperature during or after the laser irradiation. The relation between the photo-induced structures and the optical property modifications are discussed, as well as some applications.
Optics Express | 2010
Wahb Ettoumi; Yannick Petit; Jérôme Kasparian; Jean-Pierre Wolf
We derive the spectral dependence of the non-linear susceptibility of any order, generalizing the common form of Sellmeier equations. This dependence is fully defined by the knowledge of the linear dispersion of the medium. This finding generalizes the Miller formula to any order of non-linearity. In the frequency-degenerate case, it yields the spectral dependence of non-linear refractive indices of arbitrary order.
Nature Communications | 2011
Stefano Henin; Yannick Petit; Philipp Rohwetter; K. Stelmaszczyk; Zuoqiang Hao; Walter M. Nakaema; A. Vogel; T. Pohl; F. Schneider; Jérôme Kasparian; K. Weber; L. Wöste; Jean-Pierre Wolf
Because of the potential impact on agriculture and other key human activities, efforts have been dedicated to the local control of precipitation. The most common approach consists of dispersing small particles of dry ice, silver iodide, or other salts in the atmosphere. Here we show, using field experiments conducted under various atmospheric conditions, that laser filaments can induce water condensation and fast droplet growth up to several μm in diameter in the atmosphere as soon as the relative humidity exceeds 70%. We propose that this effect relies mainly on photochemical formation of p.p.m.-range concentrations of hygroscopic HNO3, allowing efficient binary HNO3–H2O condensation in the laser filaments. Thermodynamic, as well as kinetic, numerical modelling based on this scenario semiquantitatively reproduces the experimental results, suggesting that particle stabilization by HNO3 has a substantial role in the laser-induced condensation.
Applied Physics Letters | 2010
Yannick Petit; Stefano Henin; Jérôme Kasparian; Jean-Pierre Wolf
We have experimentally measured that laser filaments in air generate up to 1014, 3×1012, and 3×1013 molecules of O3, NO, and NO2, respectively. The corresponding local concentrations in the filament active volume are 1016, 3×1014, and 3×1015 cm−3, and allows efficient oxidative chemistry of nitrogen, resulting in concentrations of HNO3 in the parts per million range. The latter forming binary clusters with water, our results provide a plausible pathway for the efficient nucleation recently observed in laser filaments.
Chemistry-an Asian Journal | 2014
Ji Liu; Christophe Detrembleur; Bruno Grignard; Marie-Claire De Pauw-Gillet; Stéphane Mornet; Yannick Petit; Christine Jérôme; Etienne Duguet
Herein, we report a new drug-delivery system (DDS) that is comprised of a near-infrared (NIR)-light-sensitive gold-nanorod (GNR) core and a phase-changing poly(ε-caprolactone)-b-poly(ethylene glycol) polymer corona (GNR@PCL-b-PEG). The underlying mechanism of the drug-loading and triggered-release behaviors involves the entrapment of drug payloads among the PCL crystallites and a heat-induced phase change, respectively. A low premature release of the pre-loaded doxorubicin was observed in PBS buffer (pH 7.4) at 37 °C (<10% of the entire payload after 48 h). However, release could be activated within 30 min by conventional heating at 50 °C, above the Tm of the crystalline PCL domain (43.5 °C), with about 60% release over the subsequent 42 h at 37 °C. The NIR-induced heating of an aqueous suspension of GNR@PCL-b-PEG under NIR irradiation (802 nm) was investigated in terms of the irradiation period, power, and concentration-dependent heating behavior, as well as the NIR-induced shape-transformation of the GNR cores. Remotely NIR-triggered release was also explored upon NIR irradiation for 30 min and about 70% release was achieved in the following 42 h at 37 °C, with a mild warming (<4 °C) of the surroundings. The cytotoxicity of GNR@PCL-b-PEG against the mouse fibroblastic-like L929 cell-line was assessed by MTS assay and good compatibility was confirmed with a cell viability of over 90% after incubation for 72 h. The cellular uptake of GNR@PCL-b-PEG by melanoma MEL-5 cells was also confirmed, with an averaged uptake of 1250(±110) particles cell(-1) after incubation for 12 h (50 μg mL(-1)). This GNR@PCL-b-PEG DDS is aimed at addressing the different requirements for therapeutic treatments and is envisaged to provide new insights into DDS targeting for remotely triggered release by NIR activation.
Laser Physics | 2011
V. Loriot; Pierre Olivier Bejot; Wahb Ettoumi; Yannick Petit; Jérôme Kasparian; Stefano Henin; E. Hertz; B. Lavorel; O. Faucher; Jean-Pierre Wolf
As a contribution to the ongoing controversy about the role of higher-order Kerr effect (HOKE) in laser filamentation, we first provide thorough details about the protocol that has been employed to infer the HOKE indices from the experiment. Next, we discuss potential sources of artifact in the experimental measurements of these terms and show that neither the value of the observed birefringence, nor its inversion, nor the intensity at which it is observed, appear to be flawed. Furthermore, we argue that, independently on our values, the principle of including HOKE is straightforward. Due to the different temporal and spectral dynamics, the respective efficiency of defocusing by the plasma and by the HOKE is expected to depend substantially on both incident wavelength and pulse duration. The discussion should therefore focus on defining the conditions where each filamentation regime dominates.
Optics Express | 2008
Yannick Petit; Benoit Boulanger; Patricia Segonds; Corinne Felix; Bertrand Ménaert; Julien Zaccaro; G. Aka
We report for the first time measurements and modelization of the angular distributions of absorption and fluorescence in a monoclinic crystal. Studies on Nd:YCOB revealed specific topologies with ombilics. These new data upgrade the knowledge on low symmetry crystal optics.
Physical Review A | 2010
Wahb Ettoumi; Pierre Olivier Bejot; Yannick Petit; V. Loriot; E. Hertz; O. Faucher; B. Lavorel; Jérôme Kasparian; Jean-Pierre Wolf
Based on numerical simulations, we show that higher-order nonlinear indices (up to n{sub 8} and n{sub 10}, respectively) of air and argon have a dominant contribution to both focusing and defocusing in the self-guiding of ultrashort laser pulses over most of the spectrum. Plasma generation and filamentation are therefore decoupled. As a consequence, ultraviolet wavelength may not be the optimal wavelength for applications requiring to maximize ionization.
Optical Materials Express | 2013
Gautier Papon; Yannick Petit; Nicolas Marquestaut; Arnaud Royon; Marc Dussauze; Vincent Rodriguez; Thierry Cardinal; Lionel Canioni
We report on fluorescence and second-harmonic generation correlative microscopy of femtosecond direct laser-induced structures in a tailored silver-containing phosphate glass. We compare the spatial distributions of the related permanent electric field and silver clusters. The latter appear to be co-localized where the associated electric potential ensures favorable reduction-oxidation conditions for their formation and stabilization. Space charge separation is shown to occur prior the cluster formation. The associated electric field is a key parameter for silver clustering, thanks to electric field assisted silver ion motion. Future photonic structures combining 3D laser-structured fluorescence and nonlinear optical properties in such tailored glass will require an optimal control of the induced electric field distribution.
Applied Physics Letters | 2009
Stefano Henin; Yannick Petit; Denis Kiselev; Jérôme Kasparian; Jean-Pierre Wolf
We measured the electric charge release from single watermicrodroplets illuminated by ultrashort laser filaments in air. This charge is up to 600 times larger than from a comparable filament volume in air. In contrast, for atmospheric droplet concentrations and sizes, the volume-averaged overall droplet contribution to the charge is small as compared with that of the filaments along its whole propagation path.