Relaxation of the high lying excited states in Nd³⁺ doped YLiF₄, LaF₃ and YAG

Tunable ultra-violet laser spectroscopy is used to investigate the short wavelength fluorescence of Nd3+ in crystals of YLiF4, LaF3 and YAG. Time resolved spectra and decay time measurements were used to assign the UV and blue fluorescence lines to transitions from the 2F(2) 5 2, 4D 3 2 and 2P 3 2 excited states. This is the first report of the observation of fluorescence from the 2F(2) 5 2, level of Nd3+ in YLiF4 and LaF3. The lifetimes of these high-lying states in LaF3 are about an order of magnitude longer than in YLiF4 or YAG. At low concentration the temperature independence of the lifetimes in YLiF4 suggests that radiative relaxation may be the dominant decay process, whereas in LaF3 and YAG non-radiative decay contributes significantly. © 1990.