Energy upconversion in holmium doped lead-germano-tellurite glass

Holmium doped lead-germano-tellurite glass was prepared by the melt quenching technique. The Judd-Ofelt intensity parameters were estimated as Omega(2)=7.6x10(-20), Omega(4)=12.9x10(-20), and Omega(6)=2.5x10(-20) cm(2). Radiative transition probabilities and lifetimes were also determined for some of the levels. Room temperature upconversion emissions have been observed from Ho(3+) at 497 nm under 532 nm laser excitation, and at 557 and 668 nm under 762 nm laser excitation. The upconversion emission mechanisms were found to be due to a step wise excitation process. Upconversion emission intensity enhanced in a heat treated glass. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3431386]