Theory of wave interaction in a magnetic field of arbitrary direction

A theory is developed for the interaction of electromagnetic waves and quantum systems subjected to a magnetic field of arbitrary direction in the two-mode (four-frequency) regime. Two versions of the theory are given: 1) for investigations of spectroscopic effects; 2) for studies of the physical processes in ring lasers having anisotropic resonators. Nonlinear differential equations are derived for the slowly varying amplitudes and phase differences of the modes. These can be used to study the amplitude and frequency characteristics of waves having arbitrary polarization vectors.