Photobleaching Effects and Influencing Mechanisms of Radiation-Induced Darkening in Erbium-Ytterbium Co-Doped Fibers With Different Wavelengths of Lasers

Photobleaching effects of radiation-induced darkening in phosphosilicate Erbium-Ytterbium co-doped fibers with different laser wavelengths of 532 nm, 633 nm, and 1080 nm were studied. Both 532 nm and 633 nm lasers exhibited photobleaching effects, in which the 532 nm laser showed superior performance. In contrast, the 1080 nm laser did not exhibit any photobleaching effect. The radiation-induced attenuation spectra and continuous wave electron paramagnetic resonance spectra of fiber preform slices were tested to analyze the evolution of P-related color center defects. The influencing mechanisms of photobleaching were discussed, and a model for the recovery effect on the fibers' defect content was proposed. This work contributes to elucidating photobleaching effects and influencing mechanisms of radiation-induced darkening in Erbium-Ytterbium co-doped fibers.