Optical spectra and excited state relaxation dynamics of Nd3+ in CaF2 single crystal

Nd-doped CaF2 crystal with high optical quality was obtained by a temperature gradient technique (TGT). Energies of the crystal field levels of Nd3+ multiplets relevant to laser operation were determined based on optical spectra recorded at T = 10 K. Room temperature absorption spectra were analyzed in the framework of the Judd–Ofelt theory to calculate radiative transition rates and luminescence branching ratios for the 4F3/2 level. The 4F3/2 radiative lifetime was calculated to be 1295 μs whereas a monotonous decrease of the 4F3/2 luminescence lifetime value from 1.45 ms to 0.9 ms was observed when the temperature increased from 10 K to 300 K. The stimulated emission cross-section of 1.48 × 10−20 cm2 at 1061 nm was determined using the Fuchtbauer–Ladenburg relation. All the results showed that Nd:CaF2 would be a promising gain media in solid-state lasers.

► Nd-doped CaF2 crystal was grown by TGT (Temperature Gradient Technique) method.
► The low-temperature spectroscopic properties of the crystal were investigated.
► The lifetime of 4F3/2 level decreased with increasing temperature from 10 k to 300 k.
► Energies of the crystal field levels of Nd3+ multiplets were determined.