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Abstract: Infrared (1.2–1.6μm) luminescence in a yttrium aluminium garnet (YAG) crystal, co-doped with Yb (10 at.%) and Cr (0.05 at.%) ions, was investigated under CW laser diode pumping (λ =940nm). The Cr4+ emission band was observed with its peak at 1.35μm and measured to be about 6% with respect to Yb3+ IR luminescence (λ =1.03μm). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+–Cr4+ energy transfer is a mechanism responsible for the 3B2(3T2)–3B1(3A2) emission of Cr4+ ions. This crystal is promising as an efficient source of the near infrared emission. [Copyright &y& Elsevier]

Abstract: In this paper, some results on visible luminescence performed on Yb3+-doped gadolinium gallium garnets under 165 and 940nm excitation were presented. The upconversion luminescence was ascribed to Yb3+ cooperative luminescence and the presence of rare earth impurity ions. The gain cross-sections of Yb:GGG crystal as a function of excited-state population fraction β were studied. Emission spectra under 165nm at 20K showed there was no charge transfer luminescence in Yb:GGG. [Copyright &y& Elsevier]