I. Introduction
Semiconductor quantum-dot (QD) lasers have drawn much attention due to expected performance improvement over quantum-well (QW) lasers such as lower threshold current density, reduced temperature sensitivity, higher differential optical gain, and lower optical linewidth enhancement factor [1]. However, poor carrier capture and relaxation efficiency of the self-assembled QDs due to the inhomogeneous size distribution and the low dot density limit the performance of the QD laser. Recently, a QD-coupled-QW structure incorporating carrier tunneling injection scheme was proposed to improve the carrier capture efficiency in a self-assembled QD laser [2], [3].