Optimum crystal parameters for room-temperature Cr4+: forsterite lasers: experiment and theory

Room-temperature Cr4+:forsterite laser experience deterioration in continuo us-wave power performance due to thermal loading caused by the temperature- dependent fluorescence lifetime and the low,heat conductivity of the host. The study presented in this paper uses a numerical model to analyze the exp erimental threshold and efficiency data of Cr4+:forsterite lasers by accoun ting for pump-induced thermal gradients, the temperature: dependence of the fluorescence lifetime, absorption saturation at the pump wavelength, and e xcited-state absorption at-the lasing wavelength. Very good agreement was o btained between theoretically predicted trends and the experimental data. T he best-fit values of the stimulated emission cross-section and the excited -state absorption cross-section were determined to be 1.16 X 10(-19) cm(2) and 0.18 X 10(-19) cm(2), respectively. Optimization studies further predic t that at an incident pump power of 8 W, a 2-cm-long Cr4+:forsterite crysta l with a differential absorption coefficient of 0.31 cm(-1) should produce the highest continuous-wave output around room temperature. (C) 2000 Publis hed by Elsevier Science B.V. All rights reserved.