Linewidth Enhancement Factor in InAs/GaAs Quantum Dot Lasers and Its Implication in Isolator-Free and Narrow Linewidth Applications

The linewidth enhancement factor (αH) is an important parameter for semiconductor lasers. In this paper, we investigate, both theoretically and experimentally, the key parameters that affect αHof InAs/GaAs quantum dot lasers. Both dot uniformity and doping density are found to be critical in achieving small αHin quantum dot lasers. The prospects for quantum dot lasers in isolator-free and narrow linewidth applications are also discussed.