Modeling of passively Q-switched lasers

The intracavity photon density and the initial population-inversion density in the diode-pumped passively Q-switched laser rate equations are assumed to be Gaussian spatial distributions. These space-dependent rate equations are solved numerically, and a group of general curves are generated. These curves clearly show the dependence of the pulse characteristics on the pump- to laser-mode size ratio and the parameters of the gain medium, the saturable absorber, and the resonator. They can also be used to estimate the pulse parameters of an arbitrary diode-pumped passively Q-switched laser and to determine the optimal pump- to laser-mode size ratio. In addition, these curves are not limited to diode-pumped lasers. Sample calculations for a diode-pumped Nd3(+):YVO4 laser and a flash-lamp pumped Nd3(+):YAG laser are presented to demonstrate the use of the curves and the related formulas. (C) 2000 Optical Society of America [S0740-3224(00)00807-9].