In recent years there has been a surge of interest in semiconductor optical amplifiers (SOAs) capable of amplifying high energy optical pulses for applications in telecommunication, medical imaging and scientific research. In order for an SOA to be capable of outputting high energy optical pulses, the saturation energy for the particular SOA must be high. The traditional approach to increase the observable device saturation energy of an SOA is to reduce the effect of dynamic gain saturation. However, for high energy picosecond or subpicosecond pulses, peak intensity is significant, and dynamic gain saturation ceases to be the only mechanism responsible for observed device gain saturation. In this thesis, we analyzed the effects of nonlinear absorption within high power SOAs and found that two photon absorption acts as a significant competing mechanism for device gain saturation. Both theory and experimental results are presented in support of this conclusion.