Spectroscopic properties of 1.8 μm emission in Tm3+ doped bismuth silicate glass

The emission properties around 1.8 μm in Tm3+ doped bismuth silicate glass have been investigated. Based on the obtained Raman spectroscopy and differential scanning calorimetry curves, it is found the introduced Bi2O3 can efficiently reduce the phonon energy of silicate glass to 926 cm−1. The energy gap between glass transition temperature and onset temperature of crystallization is 169 °C. The OH− content maintains lower in glass by bubbling dry O2 during the melting process. The cut-off wavelength in mid-infrared range is as long as 5 μm. Bismuth silicate glass has high radiative transition probability of 238.80 s−1 corresponding to the Tm3+:3F4→3H6 transition compared with conventional silicate glasses. The strongest emission at 1.8 μm with a large full width at half-maximum of 238 nm is achieved from this bismuth silicate glass doped with 0.9 mol% Tm2O3. Its fluorescence lifetime at 1.8 μm is 640 μs.