Abstract
We have studied the effects of δ-p-doping on the operating characteristics of quantum dot (QD) lasers. It is well known that increasing δ-p-doping in a laser core increases both the internal loss and threshold current. For QD lasers however, it has the beneficial effects of increasing differential efficiency and saturated ground state gain. A further consequence of increased δ-p-doping is an ultra low linewidth enhancement factor (LEF) that can be tuned through zero and even made negative with increased doping at low injected current densities.