Numerical study of polarization hysteresis in VCSELs subject to orthogonal injection

We study numerically the output polarization of a vertical-cavity surface-emitting laser (VCSEL) subject to orthogonal optical injection. We focus on the width of the hysteresis cycle induced by the variation of the detuning of the injected light. For positive detuning and strong enough optical injection we find that the hysteresis width is proportional to the birefringence parameter; for negative detuning the hysteresis width is narrow and is unaffected by the injection strength. Our results are in good agreement with recent experimental observations.