Theoretical and experimental study of a passively Q-switched CO2-laser

The results are presented of theoretical and experimental studies of passive Q switching in a CO₂- laser with a nonlinear absorber. It was found that the boundaries of passive Q switching and its dynamic characteristics could be determined adequately using two-level models of the active and passive media allowing for coherent effects. However, in order to find the pulse shape, it was necessary to go beyond the scope of the two-level approximations. As a result, not only qualitative but also quantitative agreement between the theory and the experiments was obtained over a wide range of laser parameters.