Nonlinear Dynamics of the Additive-pulse Modelocked Laser
A model of the additive-pulse modelocked (APM) laser is developed, with an emphasis on nonlinear dynamics. The APM laser has been traditionally used as a stable, pulsed light source, with multiple regions of instability that hamper useful operation. Many of these instabilities are deterministic, resulting from large levels of nonlinearity, and can be exploited if understood. In this thesis, the different elements of a typical APM laser are studied, and their effects incorporated into a four-equation iterative model. The essentials of nonlinear dynamics are then presented, as tools for identifying and characterizing deterministic instabilities. The APM model is then used to simulate the laser under conditions of high non-linearity, giving rise to quasiperiodicity, period-doubling, crises, and chaos. The chaotic regions of operation are characterized by embedding dimension and largest lyapunov exponent, and some sample attractors are plotted in three dimensions. The identification of the period-doubling route to chaos, the Lyapunov exponent quantification of the chaos, and the proof of quasiperiodicity and crisis behavior all represent new accomplishments and valuable insight into the APM laser dynamics.