Acoustooptic nonreciprocity related to the Fizeau effect in a ring laser

A study is made of an optical nonreciprocity in a ring laser in the case of a collinear interaction between a traveling acoustic wave and two opposite (counterpropagating) optical waves. It is shown that introduction of an acoustic signal into the resonator of a ring laser gives rise to different frequency modulations of the opposite optical waves and creates a variable-sign optical nonreciprocity. It is shown that such a nonreciprocity can be established without modulation of the average frequency of the opposed optical waves if two traveling-wave acoustic cells or one cell with a standing acoustic wave are used.