Effect of elastic collisions on drift splitting of opposite wave frequencies in a ring laser

The linear polarizability of a ring laser medium is calculated using a collisional model described by the averaged Keilson–Storer operator. An analysis is made of the opposite-wave frequency splitting in a ring laser induced by the drift of excited atoms in the active medium. It is shown that elastic collisions decrease the frequency splitting in the case of weak drift and increase this splitting under strong drift conditions. A nonmonotonic dependence of the drift frequency splitting on the collision frequency is obtained.