POLARIZATION FLUCTUATIONS IN VERTICAL-CAVITY SEMICONDUCTOR-LASERS

We report, theoretically and experimentally, how polarization fluctuat ions in vertical-cavity semiconductor lasers are affected by optical a nisotropies. We develop a spin-eliminated (class A) description of las er polarization and show how the various model parameters can be extra cted from the experimental data. In practice, the linear anisotropies are often much stronger than the nonlinear anisotropies, so that the p olarization modes defined by the linear anisotropies form a useful bas is. For this case we derive a one-dimensional model for polarization n oise, with simple expressions for the relative strength of the polariz ation fluctuations and the rate of polarization switches. For the othe r, more extreme, case where the nonlinear anisotropies are as strong ( or even stronger) than the linear anisotropies, the spin-eliminated de scription remains valid. However, in this case the concept of polariza tion modes is shown to lose its meaning, as a strong four-wave-mixing peak appears in the optical spectrum and polarization fluctuations bec ome highly nonuniform. [S1050-2947(98)06311-2].