Passive Temperature-Compensating Technique for Microstructured Fiber Bragg Gratings

The thermal drift of the characteristic wavelength of fiber Bragg gratings (FBGs) photowritten in the core of microstructured fibers (MOFs) is significantly reduced by inserting a liquid of suitable refractive index into their holes. For instance, the spectral range of variations is divided by a factor of 4 over a temperature range larger than 20\degree C in a six-hole MOF, and the maximum sensitivity is reduced. Such passive FBG temperature compensation technique is of great interest for applications involving accurate sensing free of thermal effects

Numerical and experimental analysis of the birefringence of large air fraction slightly unsymmetrical holey fibres

International audienceCareful numerical computations show that very slight geometrical imperfections of the cross-section of actual large air-fraction holey fibres (d/Λ > 0.6) may induce surprisingly high birefringence, corresponding to beat lengths as short as few millimeters. The spectral variations of this birefringence obeys laws similar to those of elliptical core Hi-Bi holey fibres with low air-fraction. For all the tested fibres, the group birefringence numerically deduced from the only shape birefringence is in good agreement with the measured one that does not varies when strongly heating the fibres. These computations and measurements show that the contribution of possible inner stress to the birefringence is negligible

Microstructured air-silica fibres: Recent developments in modelling, manufacturing and experiment

37 pagesInternational audienceThe main modelling methods devoted to microstrutured air-silica optical fibres (MOFs) are presented and discussed. Then, the specific propagation properties of MOFs are studied in detail. Characteristics measured on fibres manufactured in our laboratory or reported in the literature are analysed. A large number of potential and demonstrated applications are presented and the obtained performances are discussed. A particular attention is given to hollow- core photonic bandgap fibres and their applications

Experimental and numerical analysis of the chromatic dispersion dependence upon the actual profile of small core microstructured fibres

International audienceThe chromatic dispersion curve of the fundamental mode in small core microstructured fibres (SCMF) is both calculated using a Finite Element Method (FEM) and measured with a low coherence interferometric method. The great sensitivity of the chromatic dispersion to variations of the geometrical parameters of SCMFs (the pitch and the diameter) is pointed out. An excellent agreement is obtained between the numerical and the experimental results over a half micrometer spectral bandwidth [1.1 µm-1.6 µm]

REFROIDISSEMENT MOLECULAIRE INDUIT PAR CHAMP ELECTRIQUE ; MISE EN EVIDENCE PAR SPECTROSCOPIE NON LINEAIRE CARS

National audienceNous avons montré qu'un refroidissement moléculaire pouvait être induit par un champ électrique statique appliqué à des molécules non polaires d'huile de paraffine. Cet effet a été mis en évidence grâce à une mesure de spectroscopie CARS (Coherent Anti-Stokes Raman Scattering). De manière complémentaire, l'exposition de molécules à un champ électrique permet de contrôler leur orientation et ainsi améliorer ou diminuer l'amplitude de leur signature vibrationnelle

Coherent combining in an Yb doped double core fiber laser

International audienceCoherent combining is demonstrated in a clad pumped Yb doped double core fiber laser. A slope efficiency of more than 70 % is achieved with 96 % of the total output power on the fundamental mode of one of the two cores. This high combining efficiency is obtained when both cores are coupled via a biconical fused taper in a Michelson interferometer configuration