title: Powerful visible (530???770 nm) luminescence in Yb,Ho:GGG with IR diode pumping.
abstract: Powerful visible luminescence in a Gadolinium Gallium Garnet (GGG) crystal, co-activated with Yb3+ (~15 at.%) and Ho3+ (~0.1 at.%) ions, is investigated under CW laser diode pumping (lambda = 938 and 976 nm). The main visible emission band is observed in the green with its peak at lambda ~540 nm) and measured to be about 10% with respect to Yb3+ IR luminescence (lambda ~1000 nm). Red (lambda ~650 nm) and near-IR (lambda ~755 nm) emission bands are also observed but are weaker (about 3-5%). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+ - Ho3+ stepwise up-conversion is the mechanism explaining the phenomenon. Ho3+ ions embedded in the crystal in small concentration are shown to form an effective reservoir for energy transferred from the excited Yb3+ subsystem and to be an efficient source of the visible emission.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kir'yanov
authors.forename: V
authors.initials: V
authors.lastname: Aboites
authors.forename: A
authors.initials: A
authors.lastname: Belovolov
authors.forename: M
authors.initials: M
authors.lastname: Timoshechkin
authors.forename: M
authors.initials: M
authors.lastname: Belovolov
authors.forename: M
authors.initials: M
authors.lastname: Damzen
authors.forename: A
authors.initials: A
authors.lastname: Minassian