Abstract

In early work on photosensitivity in optical fibers, the optically induced refractive index changes depended on glass composition and processing-related Ge defects.¹ Later work showed that high-temperature treatments could be used to increase Ge defect levels and to enhance the UV sensitivity.² More recently, it was discovered that GeO₂-doped fibers and wave-guides show extremely high UV photosensitivity when they are first sensitized by loading the glass with several mole percent of H₂ molecules.³ H₂ (or D₂) molecules are diffused inertly into an optical fiber at high pressure. Subsequent UV irradiation (e.g., 242-248 nm) causes the dissolved H₂ to react in the doped silica, altering the glass network and leading to large refractive index changes.

© 1995 Optical Society of America