On the origin of near infrared photoluminescence in Bismuth-doped aluminosilicate glass

The near infrared (NIR) photoluminescence (PL) in Bismuth-doped aluminosilicate glasses was reported about of 16 years ago. Although it has since been developed various kinds of fiber lasers and amplifiers based on the Bismuth-doped silica glasses, the main problem, namely the nature of NIR PL, remains unsolved. Here we show that this famous NIR PL in Bismuth-doped aluminosilicate glass originates from the defect, most probably positively charged oxygen vacancy V$_{O}^{2+}$ in the glass network. This defect interacts with Bi$^+$ ion in its environment via the energy transfer.