Yb-and Er-Doped single crystals of double tungstates NaGd(WO4)2, NaLa(WO4)2, and NaBi(WO4)2 as active media for lasers operating in the 1.0 and 1.5 µm ranges

Ytterbium-and erbium-doped single crystals of scheelite-like double tungstates NaGd(WO4)2, NaLa(WO4)2, and NaBi(WO4)2 and scheelite CaWO4 have been grown by the Czochralski method. The dopant concentrations in crystals are measured, and the coefficients of dopant distribution are determined to range from 0.45 to 3. The lifetimes of the Er3+ states 4 I 11/2 and 4 I 13/2 and the Yb3+ state 2F5/2 are measured, and the absorption and luminescence spectra of the crystals are studied in the vicinity of 1.0 and 1.5 µm. The data obtained are compared with the corresponding characteristics of other crystals. The possible use of the crystals studied as active media of solid-state lasers operating in the range 1.0 and 1.5 µm is discussed.