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 satur able absorber, and the resonator. They can also be used to estimate the pul se parameters of an arbitrary diode-pumped passively Q-switched laser and t o determine the optimal pump- to laser-mode size ratio. In addition, these curves are not limited to diode-pumped lasers. Sample calculations for a di ode-pumped Nd3(+):YVO4 laser and a flash-lamp pumped Nd3(+):YAG laser are p resented to demonstrate the use of the curves and the related formulas. (C) 2000 Optical Society of America [S0740-3224(00)00807-9].