Abstract
A method is proposed for calculating the frequency characteristic of a ring laser with a periodically varying frequency nonreciprocity of the resonator on the basis of the Floquet theory valid for an arbitrary ratio of the modulation frequency to the width of the parametric locking bands. Rectangular modulation of the frequency nonreciprocity is considered as an example and it is shown that the parametric locking bands are located on the quasistatic characteristic. If the constant component of the frequency nonreciprocity is comparable with the modulation amplitude, the bands approach very closely one another and their width reaches a maximum value which is approximately equal to twice the modulation frequency.