Significantly enhanced superbroadband NIR emission in bismuth-doped calcium aluminophosphsilicate glasses by PbO substitution

Glasses with the composition of 37.5SiO2–25AlPO4–12.5Al2O3–(25 − x)CaO–xPbO–0.5Bi2O3 (x = 0–25 mol%) were fabricated. Near infrared (NIR) emission located at 1260 and 1100 nm were observed when excited by 808 and 690 nm LD excitation, respectively. Significantly enhancement of NIR emission at 1260 nm has been realized by PbO introduction. Furthermore, compared with that of sample without PbO, the intensity of NIR emission located at 1110 nm form sample with 25 mol% PbO increases by a factor of 1.2, meanwhile red emission of Bi2+ decreases by a factor of 18. We propose NIR emissions located at 1260 and 1100 nm originate from Bi+ and Bi0, respectively, and PbO incorporation induce the forming of Bi+ due to the better radius match between Pb2+ and Bi+.