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

Abstract

Room-temperature Cr4+:forsterite laser experience deterioration in continuous-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 experimental threshold and efficiency data of Cr4+:forsterite lasers by accounting for pump-induced thermal gradients, the temperature: dependence of the fluorescence lifetime, absorption saturation at the pump wavelength, and excited-state absorption at-the lasing wavelength. Very good agreement was obtained between theoretically predicted trends and the experimental data. The 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 predict that at an incident pump power of 8 W, a 2-cm-long Cr4+:forsterite crystal with a differential absorption coefficient of 0.31 cm(-1) should produce the highest continuous-wave output around room temperature.