Analytical model for design criteria of passively Q-switched laser

A general and straightforward model was developed for the design of passive ly Q-switched lasers. With the second-threshold criterion and using a numer ically fitting procedure, the output pulse energy was expressed as an analy tical function of the initial transmission of the saturable absorber and th e reflectivity of the output coupler. An analytical expression for the opti mal output reflectivity was also obtained for maximizing the output pulse e nergy of a passively Q-switched laser with a given initial transmission of the saturable absorber. Excellent agreement was studied between the present results and detailed theoretical computations. A Nd:YAG laser with Cr4+:YA G as a saturable absorber was performed to illustrate the use of the presen t model.