Long-term reliability of Er-doped fibers in hydrogen environments

Accelerated tests of Er-doped fibers in hydrogen environments are carried out and as the evidence of their long-term utilization, the degradations in loss and gain are estimated. The hydrogen-induced loss-increase in Er-doped fibers with 0 to 3 percent aluminum (Al) content is formulated. As the results of quantitative investigations, it is understood that during 25 years of use, there is almost no transmission loss increase in 1.55-mu m wavelength region and at hydrogen partial pressure of 0.001 atm and 40 degrees C if there is no Al content. In case of 1 wt% Al content, the loss increase is 0.04 dB/20 m while it is 0.08 dB/20 m if the Al content is 3 wt%. Further, it is possible to describe the gain degradations, under hydrogen environment, by the increase of background losses. Under the forementioned conditions, the gain degradation is estimated to be 0.07 dB if the Al content is 1 wt% and 0.15 dB if the content is 3 wt%. Therefore, it becomes clear that their characteristics are immune to hydrogen environment in real applications.