Modelling colliding-pulse mode-locked semiconductor lasers

A discussion of three topics in the eld of non linear optics is presented We begin with the Colliding Pulse Mode locked CPM Quantum Well QW laser A large signal model consisting of a wave propagation equation for the electrical eld and a rate equation model for the material response is derived The wave propagation equation of the electrical eld is derived from Maxwell s equations in the slowly varying amplitude approximation The material dynamics are derived from semiclassical density matrix equa tions The model for the saturable absorber a reverse biased semiconductor waveguide is improved by tting critical parameter values in such a way that the model response corresponds to many body gain calculations The large signal model is used to explain femtosecond pump probe mea surements on semiconductor waveguide structures which are identical to those employed in the CPM lasers fabricated at Tele Danmark R D The femtosecond pump probe measurements show that the semiconductor waveguide response is made up of fast and slow dynamics The fast dy namics are attributed to spectral hole burning and carrier heating while the slow dynamics are attributed to carrier transport mechanisms in the semiconductor waveguide The incorporation of these fast and slow material dynamics in the large signal model are found to be important for understanding the operation principles of the CPM QW laser Thus our large signal model is used to explain the operation principles of the CPM QW laser The pulse width is found to be determined by a balance between pulse broadening in the