Broadband infrared luminescence in Bi-doped silicate glass

Glasses having composition (0.5-5)Bi2O3-40SiO2-40CaO-20MgO were synthesized by the conventional melt quenching technique. The amorphous nature of the glasses was confirmed by XRD studies. Absorption, transmittance, fluorescence, and XPS spectra were measured. Heavily Bi-doped (Bi ions up to 8 mol%) SiO2-CaO-MgO glass can exhibit broadband NIR (Near-infrared) emission at about 1245 nm (under 808 nm excitation), and the FWHM (Full Width at Half Maximum) reach up to 300 nm. The measured fluorescent lifetime is several hundred microseconds. The XPS measurements of the Bi 4f region and decay time detection for the glass samples reveal that the NIR emission should be related to lower valence Bi ions (Bi+). After the Bi-doped glass was annealed in air atmosphere, the amount of luminescent active ions decreased.