Temperature-Dependent Stimulated Emission Cross-Section in Nd³⁺:YLF Crystal

Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd³⁺ concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the ⁴F_3/2 multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K. The stimulated-emission cross-sections of the transitions from the ⁴F_3/2 to the ⁴I_9/2, ⁴I_11/2, and ⁴I_13/2 levels were obtained from the fluorescence spectrum measured at different temperatures, using the Aull-Jenssen technique. The results show consistency with most results previously published at room temperature, extending them over a broader range of temperatures. A semi-empirical formula for the magnitude of the stimulated-emission cross-section as a function of temperature in the 250 K to 350 K temperature range, is presented for the most intense transitions to the ⁴I_11/2 and ⁴I_13/2 levels.