Ho:LaF3 single crystal as potential material for 2 μm and 2.9 μm lasers

Optical properties of a Ho-doped LaF3 single crystal have been detailed investigated as a promising material for 2 μm and 2.9 μm lasers for the first time. Judd-Ofelt theory was applied to analyze the absorption spectrum to determine the J-O intensity parameters Ωt(t=2,4,6), based on which the emission probabilities, branching ratio and radiative lifetime for the as-grown crystal were all calculated. The stimulated emission cross-sections of the 5I7 → 5I8 and 5I6 → 5I7 transitions were obtained by using the Fuchtbauer-Ladenburg method. The gain cross-section for 2 μm emission becomes positive once the population inversion level reaches 30%. The Ho:LaF3 crystal shows long fluorescence lifetime of 5I7 manifold (25.81 ms) as well as 5I6 manifold (10.37 ms) compared with other Ho3+-doped crystals. It can be proposed that the Ho:LaF3 crystal may be a promising material for 2 μm and 2.9 μm laser applications.