Transient processes in Q-switched lasers with unstable resonators

The growth of a giant pulse in a laser with an unstable resonator is analyzed by solving numerically the integral equation for an open resonator using information on the state of the active medium. A study is made of the way in which the temporal and spatial characteristics of the output radiation are affected by inhomogeneity of the excitation of the active medium and nonuniformity of the depletion of the population inversion in a transverse cross section during stimulated emission. It is shown, that in contrast to lasers with stable resonators, for certain parameters of an unstable resonator it is possible to obtain output radiation which has characteristics close to those of single-mode emission.