Dy3+-doped Ge–Ga–Sb–Se glasses for 1.3 μm optical fiber amplifiers

The GexGa5Sb5Se(90−x) glasses, where x = 20, 22.5, 25, 27.5, and 30, all doped with 1000 ppm wt Dy3+ are prepared. Thermal stabilities, optical properties and 1.3 μm emission properties of the glasses are investigated. Strong fluorescence centered at 1.34 μm with a bandwidth of 92 nm is observed. Three phenomenological intensity parameters are obtained, Ω2 = 11.61 × 10−20, Ω4 = 2.79 × 10−20 and Ω6 = 1.11 × 10−20 cm2 by a Judd–Ofelt analysis. A new method estimating lifetime of overlapping energy levels is proposed. Lifetimes of 530 μs are observed for the 1.3 μm transition and the corresponding efficiency is 37.1% according to the new method.