Nd,Mg:LiTaO 3 single crystal with high optical quality was grown by Czochralski technique. Absorption and fluorescence spectra were investigated. The peak absorption cross section at 806.5 nm and peak emission cross section at 1091 nm are 6.81×10 −20 and 3.28×10 −20 cm 2 , respectively. The fluorescence lifetime was measured to be 129 μs. With a laser-diode as the pump source, a maximum 375 mW continuous-wave laser output at 1083 nm has been obtained with a slope efficiency of 7.2% with respect to the pump power.

The polarized absorption spectra, polarized fluorescence spectra and fluorescence decay curve of Nd3+ : LiLuF4 crystals are measured at room temperature. The peak absorption cross-sections are 6.944×10−20 cm2 and 1.664 × 10−20 cm2 at around 795 nm with full-width at half-maximum of 3.4 nm and 3.2 nm for π-polarization and σ-polarization, respectively. Based on Judd–Ofelt theory, the spectral parameters of Nd3+ in LiLuF4 crystals are investigated. The emission probabilities, branching ratio and radiative lifetime for the transitions from 4F3/2 are calculated. The radiative lifetime, fluorescence lifetime and quantum efficiency are 536 µs, 489 µs and 91%, respectively. Its spectroscopic parameters are also compared with those of some other important Nd3+-doped laser crystals.

A comparative study of the optical properties of Tm 3+ in LiYF 4 (YLF) and LiLuF 4 (LLF) crystals is presented. Room temperature polarized absorption spectra and fluorescence spectra for Tm 3+ in LYF and LLF were measured and analysed. By applying the Judd-Ofelt approach, the intensity parameters 2,4,6 were calculated. The radiative transition rates, branching ratios and radiative lifetimes were also obtained. The results were analysed and compared between these two samples, indicating that both of them are favourable laser media.