Crystal growth and spectroscopic characterization of Tm3+-doped KYb(WO4)2 single crystals.

In this paper we present the crystal growth and optical characterization of thulium-doped KYb(WO 4 ) 2 (hereafter KYbW). We grew thulium-doped KYbW monoclinic single crystals with optimal crystalline quality by the top-seeded-solution-growth (TSSG) slow-cooling method. Thulium spectroscopy was characterized in this host. The Judd-Ofelt parameters determined were Ω 2 =0.14×10 - 2 0 cm 2 , Ω 4 =0.21×10 - 2 0 cm 2 , and Ω 6 =0.10×10 - 2 0 cm2. The room temperature lifetimes measured for KYbW:Tm 1% were r( 1 G 4 ) =60-70 μs, τ( 3 H 4 )=90 μs and τ( 3 F 4 )=200 μs. We calculated the emission cross section for several channels. There was an important blue emission after pumping resonantly to the stoichiometric ytterbium at 980 nm, and we studied the emission channels of thulium. The presence of thulium luminescence is proof of the large transfer of energy in this compound.