Fictive temperature of silica glass optical fibers - re-examination

Fictive temperatures of several commercial silica glass optical fibers were re-measured using IR reflection method, both on the fiber surface and on the fiber cross-section. In order to increase the cross-sectional area of the fiber for a larger IR beam, fibers were sliced approximate to5 degrees off the fiber axis direction. The IR reflection peak wavenumber was nearly uniform across the fiber cladding and was close to the value obtained earlier for the fiber surface. The IR wavenumbers were converted to fictive temperature using the extrapolated relation between the IR peak wavenumber and the fictive temperature. In order to ascertain the validity of the extrapolation, the fictive temperature was also obtained by extrapolating the known relation between the cooling rate and the fictive temperature of the fibers. The fictive temperature of the optical fibers was estimated to be in the range 1600-1700 degreesC and its radial distribution in the cladding was nearly uniform. contrary to earlier results. (C) 2001 Elsevier Science B.V. All rights reserved.