Broadband Radiation-Resistant Erbium-Doped Optical Fibers for Space Applications

We explore how radiation-resistant broadband erbium-doped fibers (EDFs) can be achieved by using a carefully selected chemical composition, without specific coating or specific packaging. In this framework, we define a factor of merit, an appropriate and effective tool to design a radiation-hardened EDF amplifier (EDFA) based on a mature technology. We focus on specialty fibers, with a finely tuned composition in aluminum and erbium, guaranteeing the optimal operation of an EDFA (a 20-nm bandwidth and an optical output power level of at least 18 dBm) in the classical booster configuration throughout the entire geostationary mission. These performances are estimated thanks to a standard accelerated test, with a 300-Gy dose deposition at a dose rate of 0.4 Gy/h. We also confirmed, based on experiments and modeling, the importance of the radiation-induced absorption at pump wavelength on the EDFA degradation under irradiation.