gamma -ray irradiation durability of erbium-doped fibres

The long-term behaviour of erbium-doped fibres under gamma -ray irradiation at a low dose rate of 0.5R/year was predicted for the purpose of applying the fibres to transoceanic transmission systems, based on the experimental result that permanent defects in fibres were dominantly generated at low dose rates. The estimated degradation of transmission loss and amplification gain after 25 years in undersea were 0.04 dB/km and 0.3 dB, respectively.