Electron beam irradiation and thermal-induced effects on the spectral properties of BAC-Al in Bi/Er codoped aluminosilicate fibers

The effect of electron irradiation (5-140 kGy) on the spectral properties of bismuth active centers (BACs) in Bi/Er codoped aluminosilicate fibers (BEDFs) has been studied. It is revealed that the near-infrared (NIR) emitting BACs exhibit high radiation resistance, evidenced by the negligible change in the saturable absorption and on-off gain of BACs. In contrast, the radiation-induced absorption (RIA) increases sharply with the increasing radiation dose. The contribution of each of the defects to the RIA level has been analyzed, and it is found to be mainly linked to the generation of Al-OHC in the Al₂O₃-SiO₂ host. Furthermore, the thermal annealing on the irradiated BEDFs has also been investigated, revealing the higher thermal stability of BACs due to the thermal bleaching of Al-OHC. This is the first time that the BACs show good resistance to the strong electron irradiation.