Abstract

Fluorine-doped synthetic silica has become an important material for optical fibers transmitting ultraviolet and near-infrared radiation. Therefore the knowledge of fluorine-diffusion behavior in the high-temperature region above 1600°C is important. It influences the refractive-index profile during fiber preparation as well as during splicing and tapering of the fibers. Fluorine diffusion was previously investigated, leading to considerably different results.^1,2 To clarify this situation we determined the diffusion coefficient of fluorine between 1600 and 2000°C. We paid special attention to the influence of impurities, such as hydroxyl and chlorine, and of codopants, such as phosphorous. Because chlorine is an inherent admixture of synthetic silica made from silicon tetrachloride, we determined additionally the chlorine diffusion coefficient.

© 1993 Optical Society of America