RESUMO
We report on the growth, spectroscopy, and laser operation of monocrystalline Tm3+:SrF2. Spectroscopic investigations confirmed the presence of broad absorption and emission bands caused by inequivalent doped sites, introduced by charge compensation effects which also caused the clusterization of doping ions in the lattice. We obtained continuous-wave laser emission at about 2 µm, with efficiencies comparable with other Tm-doped crystals. We also achieved an uninterrupted tuning range of 180 nm between 1.8 and 2 µm. This characterization indicates that SrF2 enhances the cooperative mechanisms between Tm ions, helping to obtain remarkable laser performances at low doping concentrations.
RESUMO
We report on the crystal growth of the orthorhombic low-temperature ß-phase of (Y0.5,Gd0.5)F3 (YGF) single crystals. The crystals were activated with trivalent praseodymium (Pr3+) and characterized with respect to their ground state absorption and stimulated emission properties. Under InGaN-laser-diode pumping, laser oscillation was obtained at more than ten wavelengths in the green, orange, red, and dark red spectral regions. In these initial experiments, output powers exceeding 100 mW and slope efficiencies between 10% and 30% were obtained. To the best of our knowledge, these results represent the first application of YGF crystals as laser host material for any active ion.
RESUMO
The crystal structure of terbium(III) scandate(III), with ideal formula TbScO(3), has been reported previously on the basis of powder diffraction data [Liferovich & Mitchell (2004 â¶). J. Solid State Chem.177, 2188-2197]. The current data were obtained from single crystals grown by the Czochralski method and show an improvement in the precision of the geometric parameters. Moreover, inductively coupled plasma optical emission spectrometry studies resulted in a nonstoichiometric composition of the title compound. Site-occupancy refinements based on diffraction data support the idea of a Tb deficiency on the A site (inducing O defects on the O2 position). The crystallochemical formula of the investigated sample thus may be written as (A)(â¡(0.04)Tb(0.96))(B)ScO(2.94). In the title compound, Tb occupies the eightfold-coordinated sites (site symmetry m) and Sc the centres of corner-sharing [ScO(6)] octa-hedra (site symmetry ). The mean bond lengths and site distortions fit well into the data of the remaining lanthanoid scandates in the series from DyScO(3) to NdScO(3). A linear structural evolution with the size of the lanthanoid from DyScO(3) to NdScO(3) can be predicted.