Influence and its Optimal Design of Number of Stacked Layer in Quantum-Dot Lasers

This study deals with quantum dot laser-diodes (QD-LDs). The influence of highly stacked quantum dot (QD) layers in QD-LDs on the laser characteristics through experiments and numerical calculations is reported and the optimal design for the QD-stacked layer numbers is indicated. By introducing new concepts, the previously reported carrier rate equations are modified in order to include the effect of the stacked QD layer numbers. It is confirmed that the threshold current and slope efficiency between fabricated and calculated QD-LDs are almost the same. Considering low threshold current, high output power, and high slope efficiency, the optimal design of the QD-stacked layer number in our QD-LD is supposed to be 14. With this, a threshold current of 38 mA, maximum optical output power of 22.7 mW, and slope efficiency of 0.28 W/A can be obtained from the QD-LD.