A study of passively Q-switched microchip laser pulse trains yields approxi
mate, yet reliable, formulae for the peak power, pulse energy, half-width,
period, and the pulse shape in time. The pulse gain differential equation i
s made integrable by assuming that the laser absorption cross sections for
the gain and saturable absorber are equal. We compare our predictions with
an experiment which uses Nd:YAG as a gain medium and Cr:YAG as a saturable
absorber. The agreement between theory and experiment for the period, pulse
width, and the pulse energy is within 10%. (C) 1998 Optical Society of Ame
rica.