[2] [2] WANG Q, TIAN C P, WANG Y Y, et al. Review of radiation hardening techniques for EDFAs in space environment[C]// SPIE. Proceedings of the SPIE-The International Society for Optical Engineering. Bellingham: SPIE, 2015: 95211D-1-95211D-6.

[3] [3] LADACI A, GIRARD S, MESCIA L, et al. Optimized radiation-hardened erbium doped fiber amplifiers for long space missions[J]. Journal of Applied Physics, 2017, 121(16): 588-596.

[5] [5] PENG T S, HUANG Y W, WANG L A, et al. Photo-annealing effects on gamma radiation induced attenuation in erbium doped fibers and the sources using 532 nm and 976 nm lasers[J]. IEEE Transactions on Nuclear Science, 2010, 57(4): 2327-2331.

[6] [6] GIRARD S, VIVONA M, LAURENT A, et al. Radiation hardening techniques for Er/Yb doped optical fibers and amplifiers for space application[J]. Optics Express, 2012, 20(8): 8457-8465.

[7] [7] AYOUB L, SYLVAIN G, LUCIANO M, et al. Radiation hardened high-power Er3+/Yb3+-codoped fiber amplifiers for free-space optical commu-