POLARIZATION MODES IN A LASER WITH LARGE ANISOTROPIES - A STATIONARY-STATE, NON-MEAN-FIELD THEORY

We present a theory of the stationary states of a laser with large opt ical anisotropies. This new, non-mean-field, vector model is based on an extension of our former mean-field model of the polarization states of quasi-isotropic lasers [J. Opt. Sec. Am. B 9, 574 (1992)]. The lat ter is itself a vectorial extension of Lamb's mean-field scalar theory of lasers [Phys. Rev. A 134, 1429 (1964)]. The new model allows us to treat systems with large anisotropies and accounts more comprehensive ly than our former theory for the polarization competition between the gain medium and the bare cavity. A key feature of the new theory is t he treatment of the problem of beam propagation in the nonlinear aniso tropic gain medium. As an example, we consider several cases of a line ar He-Ne laser operating at 3.39 mu m. For small birefringences we jus tify the theory of quasi-isotropic lasers by showing that the modes pr edicted by both theories are nearly the same. Competition between the gain medium and the cavity is illustrated by the case of a laser conta ining two large birefringences. Limitations of the new theory are brie fly discussed.