Growth and optical properties of Ho,Yb:YAl3(BO3)4 crystal

Single crystal of holmium, ytterbium-codoped yttrium aluminium tetraborate Ho,Yb:YAl3(BO3)(4)(Ho,Yb:YAB) has been grown by the flux method. The crystal structure still belongs to the space group R-32. The absorption spectra in the visible and NIR regions have been measured at room temperature; and fluorescence spectrum of Ho, Yb:YAl3(BO3)(4) crystal are also measured at room temperature excited by 976 nm laser. Not only the strong NIR emission peaks located at 1966nm was observed, but also the visible upconversion luminescence has been found. The most strong upconversion luminescence of the Ho, Yb:YAl3(BO3)(4) crystal is S-5(5) --> I-5(8) transition (570nm), and that of F-5(5) --> I-5(8) transition (652 nm) of Ho3+ ion is 1.3 times smaller relatively. The mechanism of upconversion luminescence was discussed. (C) 2003 Elsevier B.V. All rights reserved.