Abstract

A large absorption band centered at 630 nm is known to be peculiar to certain pure silicas when drawn into fiber.¹ In this work we have studied a number of deposition and sintering conditions in the preparation of vitreous silica and have determined that this absorption band can be eliminated. Aside from basic interest, control of this defect is important in the minimization of optical loss even in the 800-900-nm transmission region (Fig. 1). We have found that sufficiently strong oxidizers introduced to a furnace atmosphere during the sintering of porous preforms are effective in eliminating the defect band. We have also established that an oxidizing atmosphere during flame deposition of the silica soot has a similar although less pronounced effect.

© 1983 Optical Society of America