Stability of passively Q-switched lasers: a system theoretic approach

The rate equations of passively Q-switched lasers are considered. These equations represent the dynamics of the photon number in the laser cavity, the population inversion of the laser, and the ground-state population of the saturable absorber, when excited by an input (pumping rate). In this paper, it is shown that for bounded inputs the laser output is bounded. Furthermore, it is shown that when the input is switched off, the laser output converges to zero asymptotically. These stability results show that passively Q-switched lasers can operate safely.