Abstract
The origin of coloration and luminescence of Se-, Te-and Bi-doped glasses and glass-ceramics were investigated. NIR luminescence was observed at around 1100 nm and 1200 nm in Bi-doped and Te-doped glasses and glass-ceramics, respectively. On the contrary, no NIR luminescence could be observed in Se-doped glass. It is suggested that the origin of coloration and NIR luminescence in these hosts is most likely to be caused by molecular Se_2 (Se_2^->, Te_2 <Te_2^-> and Bit <Bi_2^->.
