UV/visible upconversion and energy transfer between Nd3+ and Pr3+ ions in co-doped tellurite glass

Upconversion emission from Nd3+ ions in UV/blue region and energy transfer from Nd3+ ions to Pr3+ ions has been observed in tellurite glass on excitation with 532 nm radiation. The UV/blue upconversion bands from Nd3+ ions have been observed at 359, 383, 415 and 451 nm due to the D-4(3/2) -> I-4(9/2), D-4(3/2) -> I-4(11/2), D-4(3/2) -> I-4(13/2) and D-4(3/2) -> I-4(15/2) transitions, respectively. The power dependence study shows that all these transitions involve two step photon absorption process. Energy transfer from Nd3+ ions to Pr3+ ions results in the observation of upconversion emission bands of Pr3+ ions at 473, 488, 610 and 647 nm. These emissions from Pr3+ ions are due to the P-3(1) -> H-3(4), P-3(0) -> H-3(4), P-3(0) -> H-3(6) and P-3(0) -> F-3(2) transitions, respectively. The involvement of system containing a quartet of ions (Nd-Nd-Pr-Pr) in the energy transfer is supported by the power and concentration dependence studies. The time resolved emission from P-3(0) level of Pr3+ ions in co-doped samples has been recorded and the occurrence of rise time in the decay curve also supports energy transfer from Nd3+ to Pr3+ ions. (C) 2007 Elsevier Ltd. All rights reserved.