Hydrogen-induced optical loss in germanium-doped single mode fibers: Relative contributions of O-H and short wavelength edge attenuation

Reactions of hydrogen in silica optical fibers lead to the formation of O-H groups and other defects responsible for short wavelength edge (SWE) attenuation. This study examines the relative contributions of O-H and SWE to optical loss at 1310 and 1550 nm in germanium-doped single-mode fibers. Both telecom-grade and specialty optical fibers were investigated. Under benign aging conditions (< 150 °C), the effects of hydrogen pressure, temperature, and aging time were explored. Two fibers with polyimide coatings were studied for their sensitivity to hydrogen at temperatures up to 375 °C. Special cases included optical fibers pre-exposed to strong UV, gamma, and electron beam radiation, where SWE loss exhibited non-standard behavior. Multiple regression analysis was used to correlate the 1310 and 1550 nm attenuation with quantitative characteristics of O-H and SWE measured at 1390, 700, and 900 nm, respectively.