Concentration quenching of the 1470-nm emission in Tm3+-doped lead-niobium-germanate glasses

In this work, we have studied the concentration quenching of the 3 H 4 → 3 F 4 emission of Tm 3+ doped lead-niobium-germanate glasses (GeO 2 -PbO-Nb 2 O 5 ) for different Tm 3+ concentrations (0.1, 0.2, 0.5, 1, 2, and 3 wt%). The emission spectra obtained under 798 nm excitation reveal the existence of energy transfer via cross-relaxation among Tm 3+ . As a result, the intensity of the infrared 3 H 4 → 3 F 4 emission at 1474 nm decreases in relation to that of the 1820 nm emission as concentration increases. The non-exponential character of the decays from the 3 H 4 level with increasing concentration, together with the dependence of the effective decay rates on Tm 3+ concentration, indicate the presence of a dipole-dipole quenching process in the framework of a diffusion-limited regime.