Study of the Frequency-Locking Region of a Monomode Anisotropic Zeeman Laser

The experimental study of polarization in a Zeeman laser with strong $x-y$-type anisotropies makes evident the rotations of the electric field vector greater than the limiting value of $\frac{1}{4}\pi$ which is fixed by the self-consistent theory. The results are in agreement with the vectorial theory based on the resonance condition, which is necessary for the representation of such a type of quantum oscillator with nonreciprocal effects (including anisotropies). The self-consistent theory appears to provide a limit which becomes valid only for very weak anisotropies. Only the polarization of the so-called "Lamb's vector" can be described by the self-consistent theory and its rotation effectively attains $\frac{1}{4}\pi$ whatever the value of the anisotropy.