Spectroscopy of mid-infrared (2.9 μm) fluorescence and energy transfer in Dy3+-doped tellurite glasses

The decay processes relating to the potential 6H13?2 → 6H15?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 6F5?2 and 6H9?2, 6F 11?2 energy levels at 805 and 1300 nm, respectively, have established that the decay processes of the lowest excited level (i.e., 6H13?2) entirely favors multiphonon emission in a tellurite glass host. Detailed investigation of the 6H13?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 ?1 for Dy3+ concentration increases to 2 mol.%may indicate energy transfer to OH? molecules in the TZNF glass despite the low OH? content, αOH?∼ 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). © 2014 Optical Society of America.