Longer lifetime of Er3+/Yb3+ co-doped fluorophosphate glasses for optical amplifier applications

Er3+/Yb3+ co-doped fluorophosphate glasses with the molar composition of Mg(PO3)2-(50-x)BaF2-CaF2:3ErF3/xYbF3, where x = 3, 4, 5, 6, 7, 8 and 9 mol%, were prepared by a conventional melt quenching technique and studied their spectroscopic properties for fiber amplifier applications. The strong emission band at 1.53 μm corresponding to 4I13/2 → 4I15/2 transition of Er3+ ion was observed for all the studied glasses and found the optimized Er/Yb concentration of 3:4. The emission cross-section of 1.53 μm emission band was calculated to be of the order of 2.60 × 10−20 cm2 by using the McCumber theory. The effective bandwidth was found to be of the order of 84 nm. To the best of our knowledge, for the first time, longer excited state lifetime (t = ~ 15 ms) for the 4I13/2 level of Er3+ ion was noticed for the optimized Er3+/Yb3+ co-doped fluorophosphate glasses. Those results were compared to the other host matrices and found that the investigated fluorophosphate glasses are promising and attractive as gain media for laser and fiber amplifier applications.