Thermal Effect on Attenuation and Luminescence of Bi/Er Co-Doped Fiber

We investigated thermal effect on attenuation and luminescence of Bi/Er co-doped fiber (BEDF). A strong and irreversible thermal darkening effect in both near-infrared (NIR) and visible spectral range was observed, accompanied by a luminescence quenching of bismuth active centers (BACs), in temperature range from 600 °C to 800 °C. This thermal darkening effect is believed to be linked to the precipitation of metallic bismuth nanoparticles and takes place at a relatively low temperature. We also observed that the quenching of BAC-Si in the BEDF is more prominent than other BACs. The BAC-Si related emission at 1420 nm is decreased by 80% when the temperature is increased to 600 °C - before the significant thermal darkening occurs and while the quenching of others BACs is not significant.