Preparation of D 2O-treated sol-gel silica preform and OD absorption bands at IR and near-IR region

Abstract

A hydroxyl impurity in sol-gel silica glass is replaced by a deuteroxyl group to study the contributions of the OD absorption to fiber losses in the near-IR region. The hydroxyl group is successfully substituted with the deuteroxyl group by deuterium oxide vapor treatment on the gel at 800°C for 30 min. An IR absorption band due to the OD fundamental vibration is observed at 3700 nm. In the near-IR region, the third overtone, a combination of the third overtone with the SiO2 fundamental vibration, and the fourth overtone are observed at 955, 900, and 775 nm, respectively. The residual deutroxyl content tends to a decrease with increasing germanium content and with decreasing heating rate during the densification process. The contribution of these absorption bands to the fiber losses at 630 nm is negligible and at 800 nm is