Irradiation and temperature influence on the Bi-doped silica fiber

We report Bi-doped fibers prepared by modified chemical vapor deposition combination with solution doping process. The fibers are divided into three groups under Co-60 gamma radiations with different doses. The absorption spectra and fluorescence spectra of the fiber before and after irradiation are investigated. The dependence of fluorescence intensity of the fiber on temperature (-40 - 70 degrees C) are measured. Experimental results show that the radiation-induced absorptions (RIAs) of the fibers increase significantly at 700 nm and 800 nm with the increase of the irradiation dose. We ascribe the great enhancement of the RIA of the fiber to the generation of more Bi near-infrared (NIR) active centers. Because near infrared nonluminous valance state like Bi3+ captures free electrons and converts into Bi2+, and further into Bi+ under the Co-60 gamma radiations with different doses. We also find that the NIR fluorescence spectra are stable before and after irradiation under 976 nm LD excitation. The possibility of communication in a radiation environment is proved, such as in outer space is proved. In addition, the fluorescence intensity dependence on temperature in a full-temperature range is analyzed, and we find that the fluorescence intensity decreases with the increase of temperature. It is contributed to the Bi active center that Bi+ may gradually turn into nonluminous Bi metallic colloids during thermal activation. The variation law of fluorescence intensity is analyzed in the whole range of temperature. We believe that the variation law of fluorescence intensity provides data and basis for the stable operation of bismuth-doped fiber laser in the future.