CNRS Telecom Laboratory of Claude Chappe

Saint-Etienne, France

CNRS Telecom Laboratory of Claude Chappe

Saint-Etienne, France
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Godinho V.,University of Seville | Caballero-Hernandez J.,University of Seville | Jamon D.,Jean Monnet University | Jamon D.,CNRS Telecom Laboratory of Claude Chappe | And 3 more authors.
Nanotechnology | Year: 2013

A new approach is presented to produce amorphous porous silicon coatings (a-pSi) with closed porosity by magnetron sputtering of a silicon target. It is shown how the use of He as the process gas at moderated power (50-150 W RF) promotes the formation of closed nanometric pores during the growth of the silicon films. The use of oblique-angle deposition demonstrates the possibility of aligning and orientating the pores in one direction. The control of the deposition power allows the control of the pore size distribution. The films have been characterized by a variety of techniques, including scanning and transmission electron microscopy, electron energy loss spectroscopy, Rutherford back scattering and x-ray photoelectron spectroscopy, showing the incorporation of He into the films (most probably inside the closed pores) and limited surface oxidation of the silicon coating. The ellipsometry measurements show a significant decrease in the refractive index of porous coatings (n500 nm = 3.75) in comparison to dense coatings (n500 nm = 4.75). The capability of the method to prepare coatings with a tailored refractive index is therefore demonstrated. The versatility of the methodology is shown in this paper by preparing intrinsic or doped silicon and also depositing (under DC or RF discharge) a-pSi films on a variety of substrates, including flexible materials, with good chemical and mechanical stability. The fabrication of multilayers of silicon films of controlled refractive index in a simple (one-target chamber) deposition methodology is also presented. © 2013 IOP Publishing Ltd.

Smari M.,University of Sfax | Walha I.,University of Sfax | Omri A.,University of Sfax | Rousseau J.J.,CNRS Telecom Laboratory of Claude Chappe | And 2 more authors.
Ceramics International | Year: 2014

The critical properties of mixed manganite La0.5Ca 0.5-xAgxMnO3 (x=0.1 and 0.2) around the paramagnetic-ferromagnetic phase transition are investigated through various techniques such as the modified Arrott plot, Kouvel-Fisher method, and critical isotherm analysis. The magnetic data analyzed in the critical region using the above methods yield the critical exponents for (x=0.1) La0.5Ca 0.4Ag0.1MnO3 (β=0.311±0.003 and γ=1.146±0.006 at TC=226.27±0.02 K). Moreover, the estimated critical exponents of (x=0.2) La0.5Ca0.3Ag 0.2MnO3 are (β=0.288±0.002 and γ=0.948±0.008 at TC=262.31±0.06). The values deduced for the critical exponents are close to the theoretical prediction of 3D-Ising model and tri-critical mean-field model. These results suggest that the present composition should be close to a tri-critical point in the La 0.5Ca0.5-xAgxMnO3 phase diagram. © 2014 Elsevier Ltd and Techna Group S.r.l.

Battie Y.,CNRS Hubert Curien Laboratory | Destouches N.,CNRS Hubert Curien Laboratory | Chassagneux F.,University Claude Bernard Lyon 1 | Jamon D.,CNRS Telecom Laboratory of Claude Chappe | And 4 more authors.
Optical Materials Express | Year: 2011

The composition, the structure and the optical properties of mesostructured hybrid silica films elaborated by sol-gel routine are studied versus the temperature of the post treatment by comparing ellipsometric measurements, atomic force microscopy and electronic microscopy characterizations, X-ray diffraction and thermal analysis. This paper shows that the refractive index variation is a combination between the structure contraction, the solvent evaporation, the silica wall condensation and the pyrolysis of the copolymer. We also investigate the optical properties of thermally grown silver nanoparticles in the mesotructured films and we demonstrate that these properties depend on the optical properties of the host matrix and on the silver concentration profile in the film. © 2011 Optical Society of America.

Dzarova A.,Slovak Academy of Sciences | Royer F.,Jean Monnet University | Royer F.,CNRS Telecom Laboratory of Claude Chappe | Timko M.,Slovak Academy of Sciences | And 9 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2011

This paper deals with a magneto-optical study of suspensions of magnetosomes. These magnetosomes are synthesized by biomineralization process of magnetotactic bacteria, followed by steps of isolation and purification in order to obtain stable suspensions. The structural analysis evidences the good crystallinity of the magnetite particles with a diameter of 34 nm. Magneto-induced linear and circular anisotropy confirms the important role played by the chains in the orientation mechanism of such magnetic dipoles. Numerical adjustments of the linear anisotropy curves using a classical Langevin orientation model give the average number of magnetosomes per chain, about 12. © 2011 Elsevier B.V. All rights reserved.

Lebbal M.R.,University of Mentouri Constantine | Boumaza T.,University of Mentouri Constantine | Bouchemat M.,University of Mentouri Constantine | Royer F.,CNRS Telecom Laboratory of Claude Chappe | Rousseau J.J.,CNRS Telecom Laboratory of Claude Chappe
International Review on Modelling and Simulations | Year: 2012

Magneto-optical waveguides isolators are indispensable devices for stable operation of telecommunication. However, minimizing the phase mismatch between fundamental TE and TM propagation modes is an essential condition to ameliorate the isolation[1]-[3]. This condition can be satisfied depending to the substrate and the material with thickness of the guiding thin layer. The simulation carried out by MATLAB allowed deducing the conditions to decrease the phase mismatch and increase the conversion ration of modes. This last can be satisfied in an optimized waveguides made by SiO2/ZrO2 doped with ferrite of cobalt and deposited in a glass substrate, with a selected thickness of the guiding thin film. © 2012 Praise Worthy Prize S.r.l. - All Rigthts Reserved.

Amata H.,Jean Monnet University | Amata H.,CNRS Telecom Laboratory of Claude Chappe | Royer F.,Jean Monnet University | Royer F.,CNRS Telecom Laboratory of Claude Chappe | And 9 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

In the framework of optical telecommunication systems, many functions are integrated on the same substrate. Nevertheless, one of the most important, such as isolation, is achieved using discrete components. It is based on magnetic materials which are always difficult to integrate with classical technologies. This is due to the annealing temperature of magnetic materials. In this paper we present another way for the realisation of such components. We use a dip coating process to report a magnetic nanoparticles doped silica layer on ion-exchanged glass waveguide. The advantages of this method is discussed and we demonstrate its compatibility with ion-exchanged technology. By varying the refractive index of the layer, we can adjust the interaction between the waveguide and the magneto-optical layer. © 2010 Copyright SPIE - The International Society for Optical Engineering.

Hocini A.,University Of Msila | Hocini A.,University of Mentouri Constantine | Boumaza T.,University of Mentouri Constantine | Bouchemat M.,University of Mentouri Constantine | And 3 more authors.
Applied Physics B: Lasers and Optics | Year: 2010

The zero-birefringence condition is an important requirement for magneto-optical waveguide devices. It has been analyzed by means of Film Mode Matching method (FMM). The modelling is based on geometrical adjustments of the rib waveguide and especially the etch depth, which is a critical parameter in the design of rib waveguide. We determine the waveguide dimensions that would allow the same propagation constants for both polarizations TE and TM, and we have found that there are more choices for waveguide dimensions to produce birefringence-free waveguides and single-mode rib waveguide simultaneously. © Springer-Verlag 2010.

Gereige I.,King Abdullah University of Science and Technology | Robert S.,Jean Monnet University | Robert S.,CNRS Telecom Laboratory of Claude Chappe | Eid J.,King Abdullah University of Science and Technology
Microelectronic Engineering | Year: 2012

Photolithography is a fundamental process in the semiconductor industry and it is considered as the key element towards extreme nanoscale integration. In this technique, a polymer photo sensitive mask with the desired patterns is created on the substrate to be etched. Roughly speaking, the areas to be etched are not covered with polymer. Thus, no residual layer should remain on these areas in order to insure an optimal transfer of the patterns on the substrate. In this paper, we propose a nondestructive method based on a classification approach achieved by artificial neural network for automatic residual layer detection from an ellipsometric signature. Only the case of regular defect, i.e. homogenous residual layer, will be considered. The limitation of the method will be discussed. Then, an experimental result on a 400 nm period grating manufactured with nanoimprint lithography is analyzed with our method. © 2012 Elsevier B.V. All rights reserved.

Kekesi R.,Jean Monnet University | Kekesi R.,CNRS Telecom Laboratory of Claude Chappe | Royer F.,Jean Monnet University | Royer F.,CNRS Telecom Laboratory of Claude Chappe | And 10 more authors.
Optical Materials Express | Year: 2013

Three dimensional magneto-photonic crystals were realized by a low temperature sol-gel method. Self-assembled polystyrene direct opals were impregnated by CoFe2O4 nanoparticles doped silica sol-gel solution. The silica composite inverse opal structure was then created by dissolving original polystyrene photonic crystal structure using ethyl acetate. Ellipsometric and magneto-optical measurements carried-out on silicadoped monolayers evidence that the amount of nanoparticles in the matrix can reach 39%. Scanning electron microscope images of inverse opals confirm that a 3D arrangement is obtained. Transmittance measurements show a combination of photonic band gaps with the absorption of the nanoparticles. The central positions of these band gaps are in accordance with the diameter of the initial spheres through the Bragg law. Finally, nonreciprocal magneto-optical effect is demonstrated in the inverse opals through a Faraday effect hysteresis loop. It proves the ability of the method to produce magneto-photonic crystal materials. © 2013 Optical Society of America.

Battie Y.,University of Lorraine | Jamon D.,CNRS Telecom Laboratory of Claude Chappe | Lauret J.-S.,CNRS Quantum and Molecular Photonics Laboratory | En Naciri A.,University of Lorraine | And 2 more authors.
Carbon | Year: 2012

The optical properties of single walled carbon nanotube (SWCNT) films, produced by vacuum filtration, are correlated with their diameter and their in plane preferred orientation by coupling transmission and scanning electron microscopy to conventional ellipsometry. We focused on the optical anisotropy of this material and we demonstrated that it was originated from a breakdown in the selection rules. © 2012 Elsevier Ltd. All rights reserved.

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