Thermal and optical properties of Tm3+:NaLa(WO4)2 crystal

Abstract

A Tm3+-doped NaLa(WO4)2 single crystal with a dimension of Φ20 mm×40 mm was grown by the Czochralski method. Anisotropic thermal expansion coefficients of this crystal were investigated. Polarized absorption spectra, emission spectra and decay curve were recorded at room temperature. The absorption and emission cross-section were presented. Based on the Judd–Ofelt analysis, we obtained the three intensity parameters: Ω2=10.21×10-20, Ω4=2.66×10-20, and Ω6=1.46×10-20 cm2. The radiative probabilities, radiative lifetimes, and branch ratios of Tm3+:NaLa(WO4)2 were calculated, too. Luminescence lifetime of the 3H4 level was measured to be 220 μs. The stimulated emission cross-section for the 3F4→3H6 transition were determined using the reciprocity method, potential laser gain for this transition were also investigated, the gain curves implied that the tunable range is up to 200 nm.