Infrared broadband emission of bismuth-thulium co-doped lanthanum-aluminum-silica glasses

► The fluorescence of Bi-Tm co-doped SiO2-Al2O3-La2O3 glasses were investigated under 808 nm excitation. ► A NIR broadband luminescence with a full-width at half-maximum (FWHM) of 400 nm from 1000 to 1600 nm was observed. ► The mechanism of energy transfer between Bi+ and Tm3+ was presented. ► This material provides potential applications in the broadband optical amplifiers in WDM system.