A generalized model for passively Q-switched lasers including excited state absorption in the saturable absorber

A generalized model of a passively Q-switched laser is presented. It enables performance optimization including cases in which the saturable absorber exhibits both ground and excited state absorption (ESA) at the laser wavelength. The model accounts for the properties of the lasing material, the saturable absorber, and the resonator. The procedure for using this model to determine resonator and Q-switch parameters which optimize the laser's performance is described and the model is applied to reported systems to demonstrate its use.