Influence of a longitudinal magnetic field on nonreciprocal effects in a ring laser

A theoretical analysis is made of the nonreciprocal effects which occur in a ring laser when its active medium is subjected to a longitudinal magnetic field (the analysis is carried out ignoring saturation in the active medium). The difference between the frequencies of the opposite waves and the values of the excess over the threshold for these waves are shown to be related to the difference between the polarizations due to inaccuracies in the manufacture and alignment of the resonator elements. The nonreciprocal effects are considered for the case of one and two modes. A physical interpretation of the results obtained is given.