This thesis has theoretically and experimentally investigated the ultrashort optical pulse propagation in semiconductor optical amplifiers (SOAs), which is an important topic in the optical fiber communication and optical signal processing. Some new work has been done: Firstly, effects of carrier heating on the ultrashort optical pulse propagation in quantum well SOAs are first studied taking into account the holes’ non-parabolic density of states; for bulk SOAs, an accurate and simple analytical method to study carrier heating effects is presented based on Fermi-Dirac integrals approximation. Secondly, this thesis reports a novel bias current optimization method for ultrashort optical pulse distortionless amplification in SOAs based on the newly proposed bias current relation function. Detailed theoretical and experimental work is done to analyze the relation between the optimized bias current and the parameters of the input ultrashort pulse train. Finally, a novel modelling technique-quantum transmission line modelling (Q-TLM) method is proposed by combining quantum statistic description and photon-electron dynamic interaction process description. Q-TLM is used to establish models for quantum well and quantum dot structures and analyze the dynamic performance of ultrashort optical pulse propagation in SOAs. The Q-TLM technique provides an effective method to study semiconductor optical devices.