Rate equations of high gain lasers and determination of laser parameters

Rate equations are developed to describe the behavior of high gain lasers. The solution of these equations for cw operation of such lasers is the same as that obtained by Rigrod. An experimental method is described to find the gain, saturation irradiance, and losses of a given laser. This method is illustrated for a CO(2); laser. The pumping rate and lifetime of the upper laser level of this laser are established. The optimum transmittance of the coupling mirror is also calculated, using the data obtained for the actual gain, saturation, and losses in the laser. Good agreement with experiment is found.