Experimental study on activating bismuth active centers in bismuth/erbium co-doped optical fiber by ionizing radiations

Post-treatments by ionizing radiations have been proposed previously for regulating the properties of bismuth/erbium co-doped optical fiber (BEDF). In this work, the effects of common ionizing radiations (i.e. gamma ray, electron beam and mixed γ/neutron) on Bismuth Active Centers (BACs) in BEDF have systematically been investigated. Our experimental results show obvious BAC activation by ionizing radiation – evident from the increase in saturable absorption at 830 nm that is closely associated with the BAC responsible for the desirable near infrared (NIR) emissions. This radiation induced BAC activation has been confirmed from the emission of BAC associate with silica (BAC-Si). The saturation pump power of the BAC-Si emission in all irradiated samples is found higher than that in pristine (or non-irradiated) samples. In addition, the effect on emission by different radiation is found in the order of gamma ray > mixed gamma/neutron > electron beam. On the other side, we have also observed significant radiation induced unsaturable loss that can affect the pumping efficiency and Figure of Merit (FOM). •Post-treatment by ionizing radiation has been proposed for regulating the properties of bismuth/erbium co-doped optical fiber (BEDF).•Ionizing radiation effect upon BEDF was investigated in terms of radiation type and dose, doping level, and bismuth active center (BAC) types.•The ionizing radiation will offer alterative way to control and regulate the formation of BAC.•It will provide more information for the better understanding of BAC and ultra-broadband application of BEDF.