Fig. 1. Schematic diagram of ALD technology

Fig. 2. Schematic diagram of fiber irradiation experiment

Fig. 3. Simulation results. (a) Undoped Bi ions fiber; (b) Bi ions doped fiber; (c) energy deposition in Group 1# and Group 2# fiber cores; (d) energy deposition in Group 3# and Group 4# fiber cores

Fig. 4. Energy deposition in Er ions in the fiber. (a) Energy deposition in Er ions of Group 1# and Group 2# fiber cores changing with the mass fraction of Er ions; (b) energy deposition in Er ions of Group 4# fiber core changing with the mass fraction of Bi ions in the cladding

Fig. 5. RIA of the fibers treated with different irradiation doses. (a) EDF1 (the insert image showing the absorption spectra of the fibers treated with different irradiation doses); (b) EDF2; (c) RIA variation of the fibers treated with different irradiation doses at 1300 nm

Fig. 6. Fluorescence spectra of the fibers treated with different irradiation doses. (a) EDF1; (b) EDF2

Fig. 7. Changes in fluorescence lifetime of the fibers treated with different irradiation doses. (a) EDF1; (b) EDF2; (c) fluorescence lifetime change under different irradiation doses

Fig. 8. RIGV of the fibers treated with different irradiation doses. (a) EDF1; (b) EDF2; (c) changes in RIGV of the fiber at 1550 nm with irradiation dose

Fig. 9. Schematic diagram of ring cavity fiber laser structure

Fig. 10. Performance changes of the corresponding lasers of the fibers treated with different irradiation doses. (a) EDF1; (b) EDF2

Fig. 11. Threshold power of the corresponding lasers of the fibers treated with different irradiation doses. (a) EDF1; (b) EDF2; (c) threshold power change under different irradiation doses