Theory and simulation of ultrafast carrier dynamics and nonlinear pulse propagation in quantum dot semiconductor optical amplifiers

We investigate the propagation of an ultra-fast light pulse dynamically interacting with the charge carrier plasma in the active area of a quantum dot semiconductor optical amplifier (QD-SOA). The coupled spatio-temporal dynamics of light-fields and carriers in a spatially inhomogeneous dot ensemble is described on the basis of Maxwell-Bloch equations. In this approach the light fields within the QD-SOA are calculated using wave equations that are coupled to Quantum Dot Bloch equations describing the dynamics of the carriers in the active gain medium. In addition, we simulate the dynamics of the carriers in the embedding medium, including scattering of charge carriers between wetting layer and quantum dots. Our numerical results show that the shape and duration of an ultra-short pulse propagating through the amplifier is determined by a complex combination of hole level burning and dynamic scattering processes.