Weak diffraction approximation in the theory of a ring laser with a Gaussian stop

The weak diffraction approximation is used to obtain simple analytic relationships describing the diffractioninduced frequency splitting in a ring laser with a Gaussian stop. It is shown that an increase in the index of the oscillation modes generated in the laser results (for fixed diffraction losses) in a reduction in the diffraction-induced frequency splitting. It is shown that there is an optimal length of the active element for which the main component of the frequency splitting vanishes irrespective of the stop diameter and its position on the resonator axis. A study is made of the diffraction phenomena in a ring laser whose resonator is filled completely with an active medium. An analysis is made of the difference between the diffraction splitting in lasers containing even and odd numbers of mirrors in their resonators.