Polarized absorption spectra and spectroscopic parameters of Tm3+ in the TmAl3(BO3)4 single crystal

High-optical-quality single crystals of the TmAl3(BO3)4 compound were synthesized from a solution in the melt. The absorption spectra in the σ and π polarizations for the 3H6 → 3F4, 3H6 → 3H5, 3H6 → 3H4, 3H6 → 3F3, 3H6 → 3F2, 3H6 → 1G4, and 3H6 → 1D2 transitions in the Tm3+ ion were recorded at room temperature. The transition intensities were analyzed in the framework of the Judd-Ofelt theory generalized to the case of anisotropic crystals, and the following parameters of the theory were obtained: Ω2 = 6.14 × 10−20 cm2, Ω4 = 3.09 × 10−20 cm2, and Ω6 = 2.04 × 10−20 cm2. The lifetimes and the branching ratios were determined for all possible transitions.