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Abstract: Fluorine incorporation from the gaseous phase into silica glass was investigated both during the deposition of synthetic silica layers and during the sintering of pre-deposited porous silica layers, using different fluorine-containing compounds. The fluorine content dependence on the gas concentration and the influence of fluorine on the deposition efficiency of silica were determined. The results could be interpreted and quantitatively described by a simplified model of the equilibrium chemistry, valid for different fluorine sources. [Copyright &y& Elsevier]

Abstract: The absorption and emission properties of silica based ytterbium doped preforms, made by Modified Chemical Vapor Deposition, and of the drawn fibers were investigated as a function of the atmosphere during the preform collapsing. Under increasingly reducing conditions for the collapsing atmosphere, a strong UV/VIS absorption is built up, accompanied with an UV excited emission in the visible region, obviously induced by the formation of Yb2+ ions. Both the fluorescence lifetime of the Yb3+ lasing level and the cooperative fluorescence in the visible are remarkably diminished. Laser power experiments with the different fibers show a strong deterioration of the laser efficiency parallel to the degree of reduction of the doped glasses. [Copyright &y& Elsevier]

Abstract: The diffusion of phosphorus in P2O5–SiO2 glass has been investigated by annealing of doped layers on the inner surface of quartz glass tubes between 1700°C and 2000°C and measuring radial phosphorus profiles by X-ray microprobe analysis and refractive index profiling, respectively, subsequent to the tube collapse. By comparison with calculated profiles, diffusion coefficients could be determined, which are fitted by an Arrhenius function, where the preexponential D0=10−0.18cm2s−1 is constant but the activation energy decreases with increasing concentration as E=(454–56c0.32)kJmol−1K−1, valid for a concentration range, c, between 0.04 and 10mol% P2O5. The diffusion resembles that earlier determined for aluminium in SiO2 glass, but with smaller diffusivities and activation energies. [Copyright &y& Elsevier]

Abstract: We prepared hybrid fibers by filling all-silica capillaries and photonic crystal fibers (PCFs) with arsenic chalcogenide glasses. The filling technology is described in detail and a theoretical model for the prediction of the filling length in combination with a simple approximation is presented. The prepared fiber samples are analyzed in terms of optical properties by measuring their transmission spectra which exhibit band-gap guidance and are compared with numerical simulations. Finally, we compare calculations and measurements of thermal stress in such fibers. [Copyright &y& Elsevier]