Optical loss increase of phosphor-doped silica fiber at high temperature in the long wavelength region

Abstract

The wavelength-dependent loss increase in the long wavelength region is revealed for phosphor-doped silica fiber at a high temperature around 200 °C. The loss increases around 1.3 μm and becomes larger for longer wavelength regions. The loss increase is suppressed by reducing P2O5 dopant concentration. The overtone absorption of Ge–OH at 1.41 μm as well as that of Si–OH at 1.39 μm also increases markedly. The possible origin of the loss increase is discussed.