Design of quantum-dot lasers with an indirect bandgap short-period superlattice for reducing the linewidth enhancement factor

A novel gain medium consisting of direct bandgap semiconductor quantum dots (QDs) embedded in a short-period superlattice of indirect bandgap as barrier material is proposed to produce QD lasers with extremely small linewidth enhancement factor α. Our analysis has shown that at least one order-of-magnitude reduction in α can be achieved at room temperature compared to that of similar QDs embedded in direct-bandgap barriers, making low chirp, narrow linewidth semiconductor lasers feasible.