Fluorescence dynamics in Tm,Ho:YLF following 800 nm pulsed laser excitation

We have performed spectroscopic studies that examined the time evolution of the fluorescence at wavelengths between 400 and 2500 nm, emitted from an optically excited Tm,Ho:YLF crystal in response to pulsed laser excitation at 780 nm. The fluorescence intensity decay patterns have been analyzed in terms of their time and amplitude characteristics, paying attention to the dependence of these characteristics on excitation laser fluence. With the aid of a simplified model for numerical simulations, we have been able to quantify and evaluate the effects of a number of processes whose relative importance varies with excitation fluence, such as upconversion losses and ground-state depletion.