Effect of BaF2 addition on luminescence properties of Er3+/Yb3+ co-doped phosphate glasses

Er³⁺/Yb³⁺ co-doped phosphate glasses (P₂O₅-Al₂O₃-BaO-BaF₂-K₂O-Er₂O₃-Yb₂O₃) with varying BaF₂ content, were prepared by a conventional melt quenching technique and their spectroscopic properties were examined through the Raman, absorption, emission and decay measurements. Raman spectra (350–1400 cm^?1) of the Er³⁺/Yb³⁺ co-doped phosphate glasses with varying BaF₂ content, were recorded upon laser excitation at 785 nm. Near infrared luminescence spectra were measured in the 1400–1600 nm region under 970 nm diode laser excitation and characteristic band was observed at 1533 nm corresponding to ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ ion. The decay curves for the ⁴I_13/2 level of Er³⁺ ion, were measured and the lifetime is found to decrease from 7.94 to 7.70 ms when BaF₂ content increases from 0 to 8 mol% and then increases up to 7.83 ms with further increase in BaF₂ content (12 mol%). The emission cross-section, lifetime and figure of merit for the ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ ion were evaluated and compared to the other host matrices. The upconversion luminescence was measured and intense red emission was observed for all the studied samples.