Effect of GeO₂ additive on fluorescence intensity enhancement in bismuth-doped silica glass

We observed the enhancement of fluorescence intensity due to the addition of GeO₂ in bismuth-doped silica glass (BiSG), which has a peculiar fluorescence at 1.25 μm with a full width at half-maximum of 300 nm. Experimental results revealed that the fluorescence intensity from BiSG with 5.0 mol% GeO₂ increased remarkably to be 26.3 times greater than that without GeO₂ additive for the same Bi₂O₃ concentration (0.1 mol%). Furthermore, the enhanced sample showed almost the same intensity as BiSG without GeO₂ for 1.0 mol% Bi₂O₃. These results demonstrate that GeO₂ additive effectively promotes the generation of peculiar luminescent centers.