ABSORPTION AND POLARIZATION LABELING SPECTROSCOPY OF THE D1Πu-X1Σ+g TRANSITION OF Na2

No abstract availabl

UV-induced reaction of H₂ with the core of germanosilicate and aluminosilicate fiber preforms

The photosensitivity of glasses can be significantly enhanced by high-pressure low-temperature hydrogen loading prior to UV exposure. The chemical reactions that occur between hydrogen and glass under UV exposure are thus of primary importance for the understanding of the mechanisms of H2 photosensitivity enhancement. We have used infrared spectroscopy to characterize the microstructural modifications in H2-loaded optical fiber preform cores exposed to UV laser light. Infrared spectroscopy in the 3µm range is very well adapted to such a characterization because it is highly sensitive to hydroxyl groups

Étude des bandes d'absorption infrarouges v0-3, v0-4, v0-5 de l'acide bromhydrique gazeux à l'aide d'un spectromètre SISAM

The v0-3, v0-4 and v0-5 bands of H 79Br and H 81Br were studied with a SISAM spectrometer having a theoretical resolving power of 30 mK. The wave number measurements of the vibration-rotation lines in the v 0-3, v0-4 and v0-5 bands have been obtained with a precision of 20 mK, and have allowed the determination of the molecular vibrational and rotational constants of each isotopic molecule.Les bandes d'absorption v0-3, v0-4 et v0-5 des molécules isotopiques H 79Br et H 81Br ont été analysées avec un spectromètre SISAM dont la résolution théorique est de l'ordre de 30 mK. Les mesures des nombres d'ondes des raies, effectuées avec une précision de 20 mK, ont permis de préciser la valeur des constantes de vibration et de rotation de chacune des molécules isotopiques

Simultaneous interrogation of fiber Bragg grating sensors using an acoustooptic tunable filter

We describe a novel technique to provide demultiplexing of fiber Bragg grating sensors, interrogated using interferometric wavelength shift detection. Amplitude modulation of multiple radio frequency driving signals allows an acoustooptic tunable filter to provide wavelength demultiplexing. We demonstrated a noise limited strain resolution of 150 nanostrain/v(Hz) and a crosstalk better than -50 dB

Photoinscription de filtres de type Solc dans des fibres a birefringence de contrainte induite par une gaine elliptique Controle du parametre de couplage par la methode O.C.P.D

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : AR 15753 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueMinistere de la Recherche et de l'Espace (MRE), 75 - Paris (France)FRFranc

Design of a photo-written cavity neodymium doped fibre laser, tunable around a particular absorption molecular line

Experimental works have shown it is possible to realize photo-written cavity lasers with rare earth doped silicate fibres. Most of these new laser sources can be pumped by market laser diodes, what makes them valuables for their integretion in system. Furthermore, their laser effect threshold (1-2 mW), their spectral width (a few Ghz), their conversion rate, close to the theorical value and their wavelength tunablelity allow their use in a wide range of applications such as telecommunications, sensors, etc ... We present here experimental results on a particular application of this kind of lasers in the field of detection of a gas by identification of one of its absorption lines by use of classical linear spectroscopic methods. We have carried out our experiments on an absorption line of water. We present first the making process of the fibre lasers and the method used to insure their tunablelity around the selected absorption line of water. Two lasers have been designed for this work. We give their respective characteristics, i.e. their spectral width, slope, polarisation state and we compare them with the theorical values. Secondly, we give the absorption spectra obtained with both these lasers scanning their wavelength. These spectra consist on the detected light intensity versus the laser wavelength with the laser beam freely propagating through a few meters of absorbing medium. At least, we present the preliminary experimental results on the optoacoustics detection of an absorption line of water obtained using the fibre laser having the best characteristics. The obtained curve gives the detected acoustic power versus scanned wavelength range using a non optimized acoustic cell of a few cm long containing air at room pressure and temperature