LONG-TERM RELIABILITY OF ER-DOPED FIBERS IN HYDROGEN ENVIRONMENTS

Accelerated tests of Er-doped fibers in hydrogen environments are carr ied out and as the evidence of their long-term utilization, the degrad ations in loss and gain are estimated. The hydrogen-induced loss-incre ase in Er-doped fibers with 0 to 3 percent aluminum (Al) content is fo rmulated. As the results of quantitative investigations, it is underst ood that during 25 years of use, there is almost no transmission loss increase in 1.55-mu m wavelength region and at hydrogen partial pressu re 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 describ e the gain degradations, under hydrogen environment, by the increase o f background losses. Under the forementioned conditions, the gain degr adation 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 ch aracteristics are immune to hydrogen environment in real applications.