Effects of strain and GaInP₂superlattice ordering on laser polarization

Direction-dependent transition matrix elements are calculated as a function of strain and superlattice ordering for GaInP using a 6*6 LK Hamiltonian. The predicted direction dependence is in excellent agreement with the measured polarization of laser emission from broad-area strained GaInP QW lasers. Lasers with cavities oriented along the (011) direction lase with a polarization direction tilted towards the ordering planes. Lasers with (011)-oriented stripes and disordered structures emit with the conventional TE or TM slab-waveguide polarization normally expected for strained-layer lasers.