Experimentally confirmed design guidelines for passively Q-switched microchip lasers using semiconductor saturable absorbers

We present a model for passively Q-switched microchip lasers and derive simple equations for the pulse width, repetition rate, and pulse energy. We experimentally verified the validity of the model by systematically varying the relevant device parameters. We used the model to derive practical design guidelines for realizing operation parameters that can be varied in large ranges by adoption of the parameters of the semiconductor saturable-absorber mirror and choice of the appropriate gain medium. Applying these design guidelines, we obtained 37-ps pulses, which to our knowledge are the shortest pulses ever generated in a passively Q-switched solid-state laser.