Investigation of mode amplification in QD semiconductor optical amplifier

This paper presents a modelling work done primarily to investigate the carrier dynamics of the SOA when optically pumped at one or more wavelength. The model portrays the carrier dynamics for an inhomogeneous array of quantum dots (QDs) and its effect on mode propagation along the waveguide direction. A set of rate equations is used, that describes the QDs size inhomogeneity, size dependent filling factor as well as timescales and numerically solved them with the propagation equation to investigate the amplification of both the stimulated and spontaneous emission in the waveguide at the different operation regimes of the SOA. Light from external pumping changes the carrier population, gain and refractive index of the material which in turn, effects the amplification of the light along the waveguide. The rate equations used, treats an ensemble of QDs with two confined level (ground and excited state) coupled to a wetting layer (QW) level and explicitly considers only the electrons.