Optical characterization of Tm3+ in LaF3 single crystal

•A Tm-doped LaF3 sing crystal was successfully grown from the melt.•The spectral parameters of Tm:LaF3 crystal were calculated in detail.•Optical properties of Tm:LaF3 for ∼1.84 μm lasers were systematically studied for the first time.

Optical properties of a Tm-doped LaF3 single crystal have been detailed investigated as a promising material for ∼1.84 μm lasers for the first time. Judd-Ofelt theory was applied to analyze the absorption spectrum. With the J-O intensity parameters Ωt(t=2,4,6), the emission probabilities, branching ratios and radiative lifetimes for the as-grown crystal were all calculated. The stimulated emission cross-section of the 3F4 → 3H6 transition was obtained by using the Fuchtbauer-Ladenburg method. The gain cross-section for ∼1.84 μm emission becomes positive once the population inversion level reaches 30%. The fluorescence lifetime of the 3F4 manifold was measured to be 15.56 ms. Potential utility of the Tm:LaF3 crystal as laser active material at ∼1.84 μm can be expected.