Energy-transfer frequency upconversion in neodymium-sensitized praseodymium-doped PbGeO3-PbF2-CdF2 glass excited at 810Â nm

Visible frequency upconversion emission through resonant energy-transfer involving neodymium and praseodymium ions in PbGeO3-PbF2-CdF2 glass excited by a semiconductor laser at 810 nm is investigated. Luminescence emission centered around 485, 530, 610, and 645 nm, which correspond to the 3P0 → 3H4, 3P1 + 1I6 → 3H5, 3P0 → 3H6 and 3P0 → 3F2 transitions of praseodymium ions, respectively, are observed. The upconversion excitation of the Pr3+ ions excited-state emitting levels was accomplished by means of an ion-pair interaction involving ground-state absorption, multiphonon relaxation, and excited-state absorption of pump photons at 810 nm by the Nd3+ (4I9/2 → 2H9/2, 4F5/2; 4F3/2 → 2P1/2) and direct energy-transfer to Pr3+ (4G11/2 + 2K11/2, 3H4 → 4I9/2, 3P1 + 1I6). The dependence of the upconversion emission intensity upon the excitation power, and neodymium concentration are also examined.