Macroscopic versus microscopic description of polarization properties of optically anisotropic vertical-cavity surface-emitting lasers

A macroscopic model for optically anisotropic vertical-cavity surface-emitting lasers (VCSELs) is derived from a microscopic model [Burak et al., Phys. Rev. A, vol. 61, pp. 53809-53830, 2000]. This provides a rigorous generalization of the phenomenological approaches to the description of polarization properties of VCSELs used commonly in the literature. The optical anisotropy of the VCSEL structure is assumed to result from anisotropic strain of the active quantum-well material. The polarization-dependent linewidth enhancement factors and gain coefficients are calculated microscopically from the anisotropy of the valence bands. The influence of the anisotropic strain on the stability of polarization eigenmodes is investigated. A comparative study is performed between the full microscopic model and the macroscopic model on different levels of approximations. The results of the models agree very well for input/output characteristics of anisotropic VCSEL's. Also, the stability properties of polarization eigenmodes are qualitatively the same, although the ranges of stability are quantitatively different for both approaches. Incorporation of many-body effects into the analysis diminishes the agreement between microscopic and macroscopic theories.