Carrier Dynamics and Modulation Capabilities of 1.55-$\mu$ m Quantum-Dot Lasers

We present a spatially resolved model for multilayer quantum-dot (QD) lasers. The detailed model incorporates the homogeneous and inhomogeneous gain broadenings. Using this model, we examined effects of various structural parameters on the modulation response. Modulation bandwidth is increased with shortening the distance from the contacts to the active area, shortening the distance between QD layers, and with increasing the number of QD layers. The number of QD layers should be carefully chosen in order to prevent a transport bottleneck. Asymmetric positioning of the QD layers with respect to the waveguide core was found to improve the modulation bandwidth.