Thermally Activated Photobleaching of Luminescence Centers in Bismuth-Doped High Germania Fibers
This article presents the results of a study of the influence of the combined effect of laser irradiation and heat treatment on the properties of fibers with a bismuth-doped high-germania glass core. The main attention was focused on studying the influence of IR radiation on the luminescent and absorption properties of bismuth active centers (BACs). The phenomenon of BAC degradation caused by IR radiation, as well as their thermally induced reduction at temperatures above 300 ℃, was found. A phenomenological model of the processes under study is proposed. The calculation results are in good agreement with the experimental data. Characteristic parameters (activation energy, reaction rate constant) of the studied processes were obtained. In addition, the results of numerical calculations on the effect of BAC photobleaching processes on the long-term stability of bismuth fiber laser operation are given.