Photo-annealing effects for erbium doped fiber sources after gamma irradiation tests by using 532 nm and 976 nm lasers

Two EDFs with different radiation sensitivities were used in the photo-annealing tests. We compared photo-annealing efficiencies obtained by using 532 nm and 976 nm lasers. The 532 nm laser with 10 mW showed better efficiency than 976 nm laser with 290 mW in a ~30 cm EDF. The recovery rate was 5.6 seconds of the half-height recovery time. The 532 nm laser possibly excited the defects and provided some thermal energy so that the defects could be recovered. The annealing efficiency from using the 976 nm laser was close to the one purely from thermal annealing at ~330 �: . For practical tests, we also built two SPB SFSs and a bidirectional SFS and measured the output power loss dependence on pump power. Under the dose rate of 129.2 krad/hr, the recovery rate of output power loss was 0.009 dB/min when a 2.8 m EDF#1 co-pumped by both the 532 nm and the 976 nm lasers.