Beam propagation method simulation and analysis of quantum dot flared semiconductor optical amplifiers in continuous wave high-saturation regime

The authors present the investigation results of flared quantum dot (QD) semiconductor optical amplifiers (SOAs) in a continuous wave (CW) high-saturation regime using the finite difference beam propagation method (FD-BPM) model. By combining the BPM model with pre-calculated results obtained from multi-population rate equations (MPREs), the authors include in a rigorous way the non-linear gain and refractive index variation of semiconductor gain medium caused by saturation effects in QD. Using this model, a comprehensive analysis of the symmetric tapered QD SOAs is reported, verifying the influence of saturation effect on the characteristics of such devices and optimising the design of both gain and weakly index-guided structures for operation in the high-saturation regime.