Determination of the optimum absorption coefficient in Cr^4+:forsterite lasers under thermal loading

We present the results of a novel experimental and numerical investigation aimed at minimizing thermal loading effects in room-temperature Cr(4+): forsterite lasers. In the model we numerically calculated the incident pump power required for oscillation threshold to be attained by taking into account pump absorption saturation, pump-induced thermal gradients inside the crystal, and the temperature dependence of the upper-state fluorescence lifetime. Excellent agreement was obtained between 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 of 15 degrees C the optimum value of the absorption coefficient was numerically determined to be 0.64 cm(-1) . Such optimization studies, which are readily applicable to other laser systems, should make a significant contribution to the improvement of the power performance of Cr(4+): forsterite lasers at room temperature.