Enhanced 1.8 μm emission in Er~（3＋）/Tm~（3＋） co-doped lead silicate glasses under different excitations for near infrared laser

A detailed study of the fluorescence emission properties and energy transfer mechanism in Er~（3＋）/Tm~（3＋） co-doped lead silicate glasses was reported. Enhanced near infrared 1.8 μm and visible up-conversion emissions were investigated under 808 and 980 nm excitations, respectively. The energy transfer mechanism between Er~（3＋） and Tm~（3＋） was analyzed according to the absorption spectra, the emission spectra and the level structures of Er~（3＋） and Tm~（3＋）. The energy transfer efficiency between Er~（3＋） and Tm~（3＋） reached 68.1% in the Er~（3＋）/Tm~（3＋） co-doped lead silicate glasses when pumped by 808 nm laser diode. Based on the absorption spectra, the Judd-Ofelt parameters, spontaneous emission probability, absorption and emission cross sections, gain coefficients were calculated and analyzed. It was found that the calculated emission cross section and the maximum gain coefficient around 1.8 μm were 4.9×10~（–21）cm~2 and 1.12 cm~（–1）, respectively. These results indicated that the Er~（3＋）/Tm~（3＋） co-doped lead-silicate glasses had potential application in near infrared lasers.