HOW THE CARRIER MOMENTUM INFLUENCES THE POLARIZATION PROPERTIES OF A VERTICAL-CAVITY SEMICONDUCTOR LASER

By taking carrier momentum into account, we present an extension of the commonly used model that describes the polarization properties of vertical-cavity surface-emitting lasers (VCSEL's). We study how this modifies the polarization dependence of the gain saturation, and introduce the role of the crystalline symmetry of the semiconductor material. On a macroscopic level we show that a limited number of parameters is sufficient to describe fully the polarization properties of the VCSEL. On a microscopic level we show how the magnitudes of these parameters are determined by the dependence of the interband-transition dipole matrix element on the relative orientation of the carrier momentum and optical polarization. It turns out to be essential that the component of the carrier momentum in the plane of the quantum well is non-negligible. Furthermore, the relaxation rates of the carrier momentum and carrier spin are crucial in determining the magnitude of the polarization effects. Inclusion of the carrier momentum changes the interpretation of experimental results on the polarization of VCSEL's, and makes it possible to understand experimental results that were until now unexplained.