Efficiency of coupling out radiation from a resonator of a laser emitting short pulses

A previously developed method for numerically calculating the dynamics of the formation of the output beam in a laser with a plane-plane resonator, utilizing a Monte Carlo type procedure, was used in a detailed investigation of the dependences of the lasing energy losses in nonaxial beams of pulse duration τ_p comparable with the average resonator round-trip time τ_ρ on their geometry and operating regime. It was found that when the reflection coefficient of the side walls is not too high, the losses depend only on the ratio τ_p/τ_ρ while the transverse dimensions of the active zone determine the divergence of the radiation. An analytical estimate of this dependence is presented together with the limiting wall reflection coefficient above which the influence of "transverse lasing" becomes important.