DETERMINATION OF THE OPTIMUM ABSORPTION-COEFFICIENT IN CR4+FORSTERITELASERS UNDER THERMAL LOADING

We present the results of a novel experimental and numerical investiga tion aimed at minimizing thermal loading effects in room-temperature C r4+:forsterite lasers. In the model we numerically calculated the inci dent primp power required for oscillation threshold to be attained by taking into account pump absorption saturation, pump-induced thermal g radients inside the crystal, and the temperature dependence of the upp er-state fluorescence lifetime. Excellent agreement was obtained betwe en model predictions and experimental threshold data. We then used the model to calculate the optimum absorption coefficient that minimizes the incident threshold pump power. At a crystal boundary temperature o f 15 degrees C the optimum value of the absorption coefficient was num erically determined to be 0.64 cm(-1). Such optimization studies, whic h are readily applicable to other laser systems, should make a signifi cant contribution to the improvement of the power performance of Cr4+: forsterite lasers at room temperature. (C) 1998 Optical Society of Ame rica.