[48] | Active optical fiber | Sealed carbon coating, H2-loaded | Formation of stable —OH with H2, coating impedes H2 escape | RIA of H2-loaded Er-doped fiber is 3.3‒3.8 times lower than non-H2 fiber in the 750‒1700 nm range |
[49] | Active optical fiber | 980 nm photobleaching, H2-loaded, sealed carbon coating | Formation of stable —OH with H2, reduced color center concentration, coating restricts gas escape mechanism | Estimated 30 times gain in the usage lifetime of EDF laser in space using H-loaded sealed coating fiber and 980 nm pump |
[49‒50] | Active optical fiber | Sealed carbon coating, H2-loaded | Formation of stable —OH with H2, coating impedes H2 escape | After Co-source irradiation, the original Er-doped fiber exhibits a 5-fold increase in laser efficiency degradation compared to carbon-coated fibers, a 12-fold increase in laser threshold, and the RIA level of carbon-coated fibers is much lower than that of the original fibers |
[51‒52] | Active optical fiber | HACC, H2-loaded | Formation of stable —OH with H2, gas escape mechanism restricted | Under 3.15 kGy γ irradiation, Er-doped fiber post-treatment has 1/10 gain change compared to untreated fiber |
[14] | Active optical fiber | Ce element doping, H2-loaded | Reduced generation or thermal stability of phosphorus-oxygen hole centers in NIR and P1 defects in IR | Er/Yb co-doped fiber doped with Ce and loaded with H2 has gain degradation of 0.2 dB, RIA below 0.05 dB/m at 915 nm and 1545 nm after 900 Gy radiation |
[53] | Active optical fiber | Pre-irradiation, annealing | Induced defects migrate to higher energy sites, elimination of low-energy defects | Treated Er/Yb co-doped fiber shows approximately 0.16 dB/m improvement in radiation-induced losses compared to the original fiber, including 0.14 dB initial loss |
[54] | Active optical fiber | Ce element doping, photonic crystal fibers | Lower concentration of Ge in the ECPCF core results in a lower concentration of permanent color centers | Irradiation resistance of photonic crystal fibers is significantly better than that of double-clad fibers |
[55] | Active optical fiber | Ce element doping, 915 nm photobleaching | Reduced color center concentration | After 915 nm (43 W) pump photobleaching, Er/Yb co-doped fiber with Ce doping has less than 6% gain decay post-irradiation with a total dose of 1 kGy and dose rate of 0.0034 Gy/s |
[56‒57] | Active optical fiber | D2-loading, pre-irradiation, heat annealing | Reduction of POHC color center precursors, Inhibition of P2 color center formation, Deuterium radicals react with POHC color centers and glass network forming stable P-OD, Si-OD bonds | D2-loaded, pre-irradiated, and annealed Yb-doped fiber shows laser output power decay rate below 21% after 700 Gy irradiation at 1200 nm |
[58] | Active optical fiber | D2-loading, pre-irradiation | D2 interacts with OH- forming stable Si-OD and Si-D, Deuterium radicals (D·) effectively bleach radiation-induced dangling bond defects | After D2 loading at 60 ℃ and 5 MPa for 72 h followed by X-ray irradiation with an accumulated dose of 2.4 kGy, the radiation-induced gain changes for original Er/Yb co-doped fiber and pre-treated fiber are 3.13 dB and 1.81 dB, respectively |
[59] | Passive optical fiber | Quenching, pre-irradiation, annealing | High-temperature thermal processes eliminate radiation-induced defect structures (SiE' and NBOHC) | Treated fiber shows weaker ESR signal, and all defect centers, including SiE' and NBOHC, have completely disappeared |