Spectroscopy of bismuth-doped lead–aluminum–germanate glass and yttrium–aluminum–silicate glass

In this work we make a comparison between the spectroscopy of bismuth-doped lead–aluminum–germanate (Bi:PAG) glass and bismuth-doped yttrium–aluminum–silicate (Bi:YAS) glass. We report the variation in Bi absorption, emission and lifetime as the PbO, Bi2O3 and Y2O3 contents of the two glass systems were varied. As PbO and Y2O3 contents were increased the absorption strength of Bi decreased in both Bi:PAG and Bi:YAS glasses. This is because they both increase the optical basicity of the glasses. Higher optical basicity favors higher Bi oxidation states which may be optically inactive. In Bi:YAS the Bi absorption strength had a quadratic dependence on Bi2O3 content. This suggested that Bi2 dimers are the origin of Bi emission. In contrast to Bi:YAS glass, Bi:PAG glass had a non-monotonic color change with increasing Bi2O3 content, switching back and forth between yellow and pink. The yellow glasses were characterized by an isolated absorption band at 350–380 nm without the 500 and 700 nm absorption bands that were observed in the pink glasses. This was evidence that the 350–380 nm absorption band was related to a different Bi absorption center than the other absorption bands.