Analysis of characteristics of vertical-cavity surface-emitting lasers with a modified rate equation

By introducing a term of longitudinal coupling factor, we get a modified rate equation for vertical-cavity surface-emitting laser (VCSEL). Also by employing it, we give the expression for threshold current, and deduce from it that the threshold current decreases when the longitudinal coupling factor increases. For MQWs structure, the relation between cavity loss and the optimal quantum-well (QW) number is studied. We also analyze the small-signal modulation property of MQWs as well as periodic gain structure. Results show that, periodic gain structure gets advantages over general structures of VCSEL.