Engineering the polarization-dependent saturation in quantum-well surface-emitting semiconductor lasers

We discuss how the polarization dependence of the saturation in vertical-cavity surface emitting lasers (VCSELs) can be influenced by the design of the quantum-well (QW) gain medium. As an important concept in our discussion, we use carrier reservoirs, i.e., we separate the carrier population into a number of subpopulations. Specifically, we treat VCSELs in which the carriers are separated on the basis of their spin, their momentum, or on the basis of their spatial position. By numerically analyzing the rate equations for one specific case, we show how a properly chosen polarization dependence of the saturation leads to polarization self-modulation.