Strategies to reduce radiation induced gain degradation in erbium doped fiber

The behavior of erbium doped fiber amplifiers (EDFA) in a master oscillator power amplifier (MOPA) configuration was characterized using a ⁶⁰Co γ-ray source. The results indicate that power degradation and photo-anneal recovery processes simultaneously exist for erbium doped fibers with relatively low concentrations of the co-dopants cerium and germanium added. For fibers with relatively high concentrations of germanium and comparable levels of cerium co-dopants highly effective radiation hard behavior is exhibited. A fiber optimized for efficiency also provides a radiation hard EDFA where after a 100 kRad (1000 Gy) exposure, the degradation in signal gain was only 5 dB at a MOPA pump power of 315 mW.