Spectroscopy of mid-infrared (29 μm) fluorescence and energy transfer in Dy^3+-doped tellurite glasses

Abstract

The decay processes relating to the potential H613/2→H615/2 laser transition for 2.9 μm emission in single Dy3+-doped tellurite (TZNF and TZN) glasses have been investigated in detail using time-resolved fluorescence spectroscopy. The selective laser excitation of the F65/2 and H69/2, F611/2 energy levels at 805 and 1300 nm, respectively, have established that the decay processes of the lowest excited level (i.e., H613/2) entirely favors multiphonon emission in a tellurite glass host. Detailed investigation of the H613/2 luminescence decay characteristic revealed that two decay constants are involved in the TZNF glass composition; approximately 90% of the decay has a time constant (τ1) of 19.6 μs. The remaining centers decay with a time constant τ2=112 μs due to the Dy3+ fluorine bonds, which are possibly present in the TZNF glass matrix. Slight quenching of τ1 for Dy3+ concentration increases to 2 mol. % may indicate energy transfer to OH− molecules in the TZNF glass despite the low OH− content, [α(OH−)∼0.04 cm−1]; further decrease of τ1 (to 9.7 μs) was measured in TZN glass matrix, which is commensurate with the higher OH− density (α=0.15 cm−1).