Browsing by Author "Schneider, Hartmut W."

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    Drawing of fluoride glass fibers in NF3
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Staudt, Armin; Schoberth, Achim; Schneider, Hartmut W.
    Due to their low intrinsic optical loss in the infrared wavelength region, optical fibers drawn from heavy-metal fluoride glasses are currently under development for optical signal processing, technological processing and medical engineering apphcations. The susceptibility of these glasses to crystallization induced by hydrolysis, however, reduces the strength of the drawn fibers. A process designed for the fabrication of high-strength fluoride glass fibers is described. The strength of fibers drawn from glasses of the compound systems ZrF4 · BaF2 · LaFs · AIF3 (ZBLA) and ZrF4 · BaF2 · LaF3 · AIF3 · NaF (ZBLAN) was measured by a bending method. Glass surface damage was significantly reduced by adding NF3 to the furnace atmosphere, which increased the strength of ZBLAN fibers by about 40 % and that of ZBLA fibers by even about 75 %. ZBLA fibers drawn in an atmosphere containing fluorine exhibit a mean bending strength in the order of 1400 MPa, which is almost the strength level of smoothly etched fibers. The strength of the fibers that have been etched in a ZrOCl2 solution is shown to be correlated with the light scattering of the preform; it was found to be possible to make fluoride glass fibers with a mean bending strength of at least 1600 MPa.
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    Influence of drawing conditions on the tensile strength of fluoride glass optical fibers
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1987) Schneider, Hartmut W.; Schoberth, Achim; Staudt, Armin
    Heavy-metal fluoride glass fibers are currently developed due to their potential ultra-low loss window in the 2 to 4 µm wavelength region, which makes them attractive candidates for future long-distance optical communication links. Extrapolations suggest even lower intrinsic losses for barium fluorozirconate glasses than for silica. However, the tendency of present glass compositions to crystallize makes fiber drawing difficult and results in poor mechanical performance. It is reported here on glass preparation and drawing experiments. Using the standard Zr-Ba-La-AI glass composition the effect of preform surface preparation on fiber tensile strength is demonstrated. Application of a novel ZrOCl2 etching technique, which is described in detail, resulted in improved fiber strength. Drawing temperature has to be controlled in a narrow range of ± 3 K. Under optimized condifions fibers with a mean tensile strength of 400 MPa were obtained, which is an improvement by a factor of 2 in comparison to previous results. Removing preform surface crystals has also a positive effect on fiber attenuation. The etching procedure proved to be a valuable tool in fluoride glass development.