Dependence of optical gain on crystal orientation in surface-emitting lasers with strained quantum wells

We analyze theoretically optical gains in vertical-cavity surface-emitting lasers (VCSELs) for various crystal orientations. The calculation based on the multiband effective-mass theory takes into account the effects of anisotropy and nonparabolicity on the valence subband dispersion. It is found that in VCSELs employing InGaAs/InP strained quantum wells (QWs) with non-(001) orientations except (111), the polarization in the QW plane can be controlled and high gains are obtained. In particular, the gains in VCSELs with (NN1)-oriented (N≥2) strained QWs are markedly higher than those in the equivalent (001) lasers.