Impact of Quantum Dots on III-Nitride Lasers: A Theoretical Calculation on Linewidth Enhancement Factors

III-nitride quantum dot (QD) lasers have potential applications in visible light regime, yet one of its most important dynamic parameters, the linewidth enhancement factor (LEF), has been rarely studied. We studied the LEF of InGaN QD lasers with a comprehensive theory model and found that the LEF values of InGaN QD lasers can be smaller and more robust against inhomogeneous broadening than those of InGaAs QD lasers. In addition, the LEF improvement from quantum well to QD in III-nitride semiconductors is much larger than that in III-arsenide. It is believed that the large confinement energy in HI-nitrides and atomic-like density of states of QDs contribute to these advantages of III-nitride QD lasers. Our results not only reveal the advantages of using III-nitride QD for high spectral purity, low-chirp laser applications, but also provide a general guideline for designing QD lasers with lower LEF values in various semiconductor materials.

Automated summary

In this study, the linewidth enhancement factor (LEF) of III-nitride quantum dot (QD) lasers was investigated using a comprehensive theoretical model. It was found that the LEF values of InGaN QD lasers can be smaller and more robust against inhomogeneous broadening than those of InGaAs QD lasers. Additionally, the improvement in LEF from quantum well to QD in III-nitride semiconductors is greater than that in III-arsenide. These findings not only highlight the advantages of III-nitride QD lasers for high spectral purity and low-chirp applications, but also provide a general guideline for designing QD lasers with lower LEF values in various semiconductor materials.