Phosphorus-dopant effect on hydroxyl absorption increases in silica glasses and fibers

Abstract

The effects of phosphorus-dopant and chemical reaction of H 2 on the absorption due to OH in silica glasses and fibers were investigated. In GeO 2 -P 2 O 5 -doped silica glass, the chemical reaction of H 2 caused a phosphorus-associated OH absorption increase at around 3.05 μm, as well as a Si(Ge)-OH absorption increase at around 2.75 μm. On the other hand, in P 2 O 5 -doped silica glass, the Si-OH absorption at about 2.73 μm hardly increased because of the absence of GeO 2 . However, the P 2 O 5 -doped silica glass showed the 3.41 μm OH absorption increase. This absorption at 3.41 μm is thought to be due to OH associated with the non-bridging oxygen of P=O through hydrogen bonding. Overtone bands of the 3.05 and 3.41 μm OH absorptions were so broad that their absorption peaks could not be observed in optical fibers.