Emission characteristics of Pr-doped Ga2S3-GeS2-CsX (X=Cl and Br) glasses in the visible region

Since Pr3+ ion has various emission bands in the visible region, Pr3+-doped materials are expected to be a potential candidate as laser media. In the present study, sulfide halide glasses based on Ga2S3-GeS2-CsX (X=Cl, Br), containing 20 mol% or more of CsX, and doped with Pr3+, were prepared for investigation of the visible spectroscopic properties of these glasses. The absorption edges were located around 460 nm and various emission bands in the visible region were observed with 450 nm excitation. Judd-Ofelt analyses were performed and total radiative transition rates from the 3Pj levels of Pr3+ were estimated. The lifetime of the decay was approximately 10 μs for the emission at 654 nm due to the 3P0→3F2 transition. The emission quantum efficiencies were estimated from the ratio of the emission lifetime to the radiative transition lifetime calculated with the Judd-Ofelt analyses. The large efficiencies were attributed to the low phonon energies of the glass matrices compared with the energy gap between the 3P0 and the next lower level.