Patent ID: 6334338
Filing Date: 2002-01-01
Classification: C03B

Abstract:
A process for preparing optical fiber, comprising the step of drawing fiber from a preform comprising a sol-gel silica tube, the tube formed by a process including the steps of, prior to sintering the tube:providing a silica dispersion, forming from the dispersion a gelled tube comprising water, hydroxyl groups, and refractory metal oxide particles, heating the entire tube to a temperature ranging from 400 to 800Â° C., and while the tube is at the temperature, treating the tube with a gaseous mixture comprising one or more non-oxygenated sulfur halides, the treatment performed for a time period that provides sufficient diffusion of the one or more sulfur halides into the tube such that at least one effect selected from the group consisting of reducing the concentration of water and hydroxyl groups in the tube, reducing the size of at least a portion of the refractory metal oxide particles in the tube, and reducing the concentration of refractory metal oxide particles in the tube is achieved, and subsequent to treating with the gaseous mixture, flowing a gas comprising oxygen over the tube, such that chlorine is removed from the tube.