Infrared emission spectroscopy and upconversion of ZnO-Li2O-Na2O-P2O5 glasses doped with Nd3Â + ions

Glasses with composition 20ZnO-10Li2O-10Na2O-(60-x)P2O5-xNd2O3 containing Nd3 + ions were analyzed using density calculations and optical absorption spectroscopy together with excitation and emission luminescence measurements. The Judd-Ofelt intensity parameters (Ω2, Ω4, Ω6) were calculated and their variation correlated with the physical properties. Infrared emission spectra were recorded at an excitation wavelength of 581 nm. The emission spectra showed emissions at 872 nm, 1053 nm and 1325 nm which corresponded to the 4F3/2 → 4I9/2, 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 transitions. A decrease in the emission intensity occurred beyond 1.5 mol% Nd2O3 doping which was explained on the basis of concentration quenching of the ions. The infrared to visible upconversion process was also investigated for the prepared glasses. Three main emission bands at 530 nm, 590 nm and 687 nm were observed for excitation at 870 nm. These emission bands originated form the 4G7/2 level. Excited state absorption and energy transfer upconversion mechanisms which may be responsible for the upconversion were also discussed in the present work.