Jacques Lucas

Chemical and physical compatibilities of fluoride and fluorophosphate glasses

Abstract Based on a composite preform concept, a systematic investigation has been carried out in order to qualify a low-refractive-index fluorophosphate glass that would be chemically and physically compatible with a low-phonon-energy barium-indium-gallium-based fluoride glass. Special attention is paid to the stability towrds devitrification of the solid solutions that may form at the interface of the two glasses and to the thermomechanical compatibility of the fluoride and fluorophosphate glasses. The most significant result is a preform that exhibits a theoretical refractive index difference, Δn, of nearly 0.07.

High-Purity As-S-Se and As-Se-Te Glasses and Optical Fibers

We describe a procedure for the preparation of As-S-Se and As-Se-Te glasses with low contents of gas-forming impurities (hydrogen, oxygen, and carbon) via melting of extrapure-grade elements in an evacuated silica ampule and purification of the melt by chemical distillation. The impurity concentrations in the glasses thus prepared have been reduced to the following levels: hydrogen, <0.02; oxygen, 0.2; carbon, <0.02; silicon, <0.4 ppm by weight. Using the double-crucible method, we have fabricated glass fibers with various ratios of the core and cladding diameters (1: 25 to 9: 10), protected with a tetrafluoroethylene/1,1-difluoroethylene copolymer coating, which have an average bending strength of 0.5–1 GPa. The minimal optical losses are 150 dB/km at 6.6 μm in multimode As-Se-Te glass fibers and 60 dB/km at 4.8 μm in As-S-Se glass fibers. The effect of microinhomogeneities in the melt on the optical performance of arsenic sulfoselenide glass fibers fabricated by the double-crucible method is examined.

Tellurium halide glass fibers : preparation and applications

Abstract Tellurium halide (TeX) glasses were prepared from high-purity raw materials which were purified in a silica set-up in order to eliminate the surface oxides. All the starting elements were then distilled. The rod in tube method was used to obtain TeX glass fibers having a core-cladding structure. The fiber attenuation was measured by using a Fourier-transform infrared (FTIR) spectrometer. The fiber losses, regularly obtained, were

Low-phonon waveguides made by F-/Cl- exchange on fluoride glasses

Guiding structures have been produced on the surface of fluoride glass by ionic exchange between fluoride ions of the substrate and chloride ions from HCl gas. The planar waveguides have been qualified by using analytical tools (SEM, EDX, SIMS) and optical characterizations such as m-lines method.

Tellurium halide optical fibers

Abstract New infrared fibers, the TeX glass fibers, operating from 3 to 13 μm, have been developed. Tellurium halide based glasses have been optimized to produce low loss optical core-clad fibers in the 7–9.5 μm domain, and two drawing techniques are described. IR spectroscopy of organic species have been performed with core-clad fibers.

Sodium fluorometaphosphate glasses with high rare earth ion concentrations

Abstract Vitreous areas in the systems NaPO3-BaF2-REF3 (RE: rare earth) are given. Particularly stable glass compositions have been found and characterized by determining the characteristic temperatures, refractive index, expansion coefficient and density. The evolution of these physical characteristics with the RE ion for the composition 0.60NaPO3-0.20BaF2-0.20REF3 has been examined.

Biological tissues infrared analysis by chalcogenide glass optical fiber spectroscopy

Owing to their low losses in the 2-12 micrometers region, the Te- As-Se glass fibers are used for infrared light transportation as well as sensing element based on evanescent wave absorption mechanism. The efficiency of the system is improved by tapering the fiber diameter in the sensing zone. With this kind of sensor, infrared spectra of biological tissue have been obtained. Spectra of mouse liver have been especially recorded in order to detect spectral differences between the healthy and the tumoral states of mouse liver.

Infrared glass fibers for evanescent wave spectroscopy

IR glass optical fibers have been developed in order to optimize their response when they are used as evanescent wave chemical sensors. The diameter of the sensitive part of the fiber can be reduced by tapering the fiber during the drawing process or by chemical polishing. In using an FTIR spectrometer associated with a MCT detector, it was possible to evaluate the influence of the fiber diameter on the polymer coating IR signature as well as the sensitivity of a such sensor. The high flexibility of thin fibers allows the achievement of a detection probe which has been introduced in a microwave oven in order to follow a chemical reaction. It is verified that the chalcogen-based fiber is not sensitive to microwave radiation and gives excellent on line IR fingerprints to check kinetics and reaction mechanisms.

The structure of a boron oxyfluoride glass, an inorganic cross-linked chain polymer

Abstract A combination of 19 F and 11 B NMR studies as well as ion dynamics computer simulation was used to establish the structure of the recently described vitreous material BO1.3F0.4. The cross-linked spaghetti structure suggested earlier is confirmed.

Boron oxyfluoride glasses in the BOF system: new polymeric spaghetti-type glasses

Direct reaction at T = 200°C of gaseous BF3 on B2O3 in a closed silica tube leads to BOF glass formation in the cold part of the vessel. The vitreous material obtained from vapour phase condensation has a weak dimensionality as indicated by the low glass transition temperature, Tg = 60°C. The relationship between the trimeric molecular form, B3O3F3, and the polymer glass (BOF)n is discussed with respect to formation conditions and glass decomposition.