Experimental-Simulation Analysis of a Radiation Tolerant Erbium-Doped Fiber Amplifier for Space Applications  
[PERSON]  
1 Laboratoire Hubert Curien, UMR CNRS 5516, Universite Jean Monnet, 42000 Saint-Etienne, France; [EMAIL_ADDRESS] (A.F. ); [EMAIL_ADDRESS] (A.M.); [EMAIL_ADDRESS] (C.C. ); [EMAIL_ADDRESS] (M.M.K.S. ); [EMAIL_ADDRESS] (E.M.); [EMAIL_ADDRESS] (Y.O. ); [EMAIL_ADDRESS] (A.B.) [PERSON]  
1 Laboratoire Hubert Curien, UMR CNRS 5516, Universite Jean Monnet, 42000 Saint-Etienne, France; [EMAIL_ADDRESS] (A.F. ); [EMAIL_ADDRESS] (A.M.); [EMAIL_ADDRESS] (C.C. ); [EMAIL_ADDRESS] (M.M.K.S. ); [EMAIL_ADDRESS] (E.M.); [EMAIL_ADDRESS] (Y.O. ); [EMAIL_ADDRESS] (A.B.) [PERSON]  
2 Department of Electrical and Information Engineering, Politecnico di Bari, Via [PERSON] 4, 70125 Bari, Italy; [EMAIL_ADDRESS]  
[PERSON]  
1 Laboratoire Hubert Curien, UMR CNRS 5516, Universite Jean Monnet, 42000 Saint-Etienne, France; [EMAIL_ADDRESS] (A.F. ); [EMAIL_ADDRESS] (A.M.); [EMAIL_ADDRESS] (C.C. ); [EMAIL_ADDRESS] (M.M.K.S. ); [EMAIL_ADDRESS] (E.M.); [EMAIL_ADDRESS] (Y.O. ); [EMAIL_ADDRESS] (A.B.) [PERSON]; [PERSON]; [PERSON]; ouerdane. ; [PERSON]; ouerdane. ; ouerdane. been demonstrated that active fiber represents the most radiation-sensitive part of an EDFA [9; 10]. The radiation effects on the optical fibers appear through three macroscopic phenomena. Among them, the main one is the RIA. It is an increase in the optical fiber losses that appear during irradiation. It is caused by the generation of point defects (color centers) in the host silica-based glass matrix, that lead to new absorption bands in the band gap. Generally, RIA increases with TID and then reduces partially after irradiation is stopped. The second effect is the RIE: it is constituted by Cerenkov light and radioluminescence light, that is, the light emission from pre-existing or radiation-induced centers, excited by the radiation. The last effect is the RIC, that takes place at high doses or at high neutron fluences [9; 11; 12]. The RIA directly affects the gain of the system. REDFs have been shown to be much more sensitive to radiation than telecom-grade germanosilicate optical fibers [13; 14]. In fact, this vulnerability is not linked to the presence of RE ions, such as Er\({}^{3+}\) and Yb\({}^{3+}\) ions, but it is due to the presence of co-dopants, such as Al or P [8; 15], added to the glass matrix to facilitate the incorporation of RE ions and to prevent the formation of RE ions clusters that limit the amplification efficiency [1; 16]. Under steady-state radiation, for example, optical fibers can be classified into three groups, considering their RIA levels: sensitive, tolerant or resistant fibers. Examples of radiation-sensitive optical fibers include all fibers doped with P and/or Al in their core or cladding: their losses are so high that dosimeters are today based on such fibers. Among the radiation-tolerant optical fibers are the telecom-grade germanosilicate optical fibers, without P in their core and cladding, whereas radiation-hardened optical fibers are the ones with pure silica or F-doped cores and F-doped cladding, and N-doped optical fibers [9; 17; 18]. The sensitivity of REDFAs to ionizing radiation manifests itself mostly with a gain degradation. Over the years, various techniques have been developed at the component level to make REDFAs more radiation-resistant, including co-doping of the REDF core with cerium ions and/or pre-loading it with H\({}_{2}\) or D\({}_{2}\)[19; 20; 21]. The use of co-doping with cerium is justified by its ability, depending on its multivalent state, to trap electrons or holes that may be created during the radiation exposure and may have a significant contribution to the P- or Al-related defects generation [22; 23]. During the last 30 years, the topic of point defects related to P and Al in the amorphous silica matrix, as well as in the active and passive optical fibers, has been investigated by researchers [24; 25].