The observation of OH in annealed optical fiber

Effect of temperature and irradiation on fused silica optical fiber for temperature measurement

“…Therefore, it is considered that the difference of these spectra when temperature was kept at 1000°C was caused by the difference of their core, that is, pure and F-doped silica. It has been reported that devitrification occurred and crystals grew in optical fiber above 850°C [7] and that dopant in the core was the main element initiating nucleation within the glass matrix [7,8]. In Fig.…”

Investigation of the long-term stability of arc-induced gratings heat treated at high temperatures

“…It is known that during annealing in air at high temperatures, the hydroxide anion OH − is absorbed from water vapour leading to a reduction of the glass viscosity, to an increase in the OH − band near 1.4 μm (see, for instance, Fig. 4), and it also enhances crystallization [6]. Another factor that contributes to crystallization is oxygen loading that also occurs during annealing in air at 1000°C, and it saturates in about 200 h [7].…”

Temperature measurement by thermo-luminescence of fused silica optical fiber under irradiation environment

“…Another possibility will be an enhanced recrystallization of the clad glassy structure and a resultant degradation of the clad and of the core/clad interface. It was reported that impurities will promote recrystallization of fused silica 6 and the fluorine is typically the case as offering a nucleation site for recrystallization in the glass matrix 6,7 . The apparent increase of the base-line luminescence was not observed at 900C.…”