Saturation of 640-nm absorption in Cr4+:YAG for an InGaN laser diode pumped passively Q-switched Pr3+:YLF laser

We measure the absorption recovery time, the ground- and excited-state absorption cross sections of a Cr4+:YAG crystal at 640 nm for the first time. A pump-probe measurement reveals the existence of two recovery times of 26 ns and 5.6 mu s. By a Z-scan experiment, the ground- and excited-state absorption cross sections are estimated to be 1.70-1.75x10(-17) and 0.95-1.00x10(-17)cm(2), respectively. The adequacy of the proposed model and the accuracy of the estimated parameters of the saturable absorber are verified by reproducing the experimentally obtained performance of a passively Q-switched Pr3+:YLF laser with the Cr4+:YAG saturable absorber from rate equation analysis. (C) 2015 Optical Society of America