Hydrogen-induced losses and their effects on optical fiber reliability

It is known that hydrogen induced losses can occur in silica based optical fibers. There are several different mechanisms by which these losses can occur. Molecular H₂ can cause losses in any silicate fiber, regardless of the glass composition. Hydrogen can also react at defect sites in fibers, giving rise to OH formation and other losses. The reaction rates and the effects on the loss of a fiber are dependent on the doping used in making the fibers. Hydrogen loss effects are reviewed for fibers of various types, including Erdoped amplifier fibers. The use of hermetic coatings as a means of avoiding hydrogen induced losses is briefly reviewed. Where possible, the methods used to predict long term loss increases are also discussed.