Simultaneous Ce Ion Doping in Core and Cladding to Enhance the Radiation Resistance of Erbium-Doped Fibers

Erbium-doped fibers (EDFs) suffer from radiation-induced absorption (RIA) and radiation-induced gain variation (RIGV) under ionizing radiation, which limit their applications in space optical communication systems. To address this issue, a novel core–cladding Ce co-doped fiber is proposed, in which core Ce suppresses radiation-induced defect formation while cladding Ce reduces localized energy deposition in the fiber core. GEANT4 Monte Carlo simulations were performed to optimize the Ce-doping configuration, and three kinds of fiber samples, namely conventional erbium-doped fiber (EDF), core Ce co-doped EDF (CEDF1), and core–cladding Ce co-doped EDF (CEDF2), were fabricated for experimental validation. At a total dose of 1200 Gy, CEDF2 exhibits a 40.5% reduction in RIA and a 58.1% reduction in RIGV compared with the conventional EDF. The experimental results demonstrate that the proposed core–cladding Ce co-doped structure effectively enhances the radiation resistance of erbium-doped fibers and provides a practical design strategy for radiation-hardened active optical fibers.