The diffusion coefficient and solubility of water in silica glass optical fiber cladding were measured at 600 to 800C and were compared with the corresponding values of bulk silica glasses. It was found that the diffusion coefficient was slightly lower and the solubility was appreciably higher in optical fiber, especially at low temperatures, compared with those in bulk silica glasses. The observed trend was consistent with the expected effect of fictive temperature.

Water Diffusion into a Silica Glass Optical Fiber. S.Berger, M.Tomozawa: Journal of Non-Crystalline Solids, 2003, 324[3], 256-63