Jb. Macchesney et al., OPTICAL FIBERS BY A HYBRID PROCESS USING SOL-GEL SILICA OVERCLADDING TUBES, Journal of non-crystalline solids, 226(3), 1998, pp. 232-238
We have successfully developed a sol-gel process to produce large sili
ca glass bodies to be used as optical fiber pre form overcladding tube
s which meet the demands of optical fiber. We have made and tested tub
es weighing approximately 4.5 kg, which comprise about 90% of the even
tual fiber's mass. This sol-gel process uses colloidal silica disperse
d in high pH water. The sol is cast, gelled by reducing the pH and dri
ed to a porous tube. The dried body is heat treated to remove organics
, to dehydrate and to purify by removing both refractory oxide particl
es and transition metal ions to the parts/billion range and then sinte
red to transparency in He. These tubes are competitive with vapor depo
sited synthetic silica tubes and produce fiber meeting current commerc
ial standards. Net shape formation of large precision glass bodies by
gel casting is demonstrated. (C) 1998 Elsevier Science B.V. All rights
reserved.