Regime of beatings of counterpropagating waves in a Zeeman ring laser in a strong magnet field

We have theoretically and experimentally studied the regime of beatings of counterpropagating waves in a Zeeman ring laser under the action of strong fields of ring permanent magnets on the active medium. We have for the first time calculated and measured the dependences of the frequency bias and the intensity of counterpropagating waves of such a laser on the lasing frequency detuning relative to the frequency of the gain line centre. We have revealed some features in the dependence of the frequency bias on the magnetic field strength, associated with the nonlinearity of the active medium polarisability in strong inhomogeneous magnetic fields.