20 THz intensity modulation on pulses from a self-modelocked Ti:sapphire laser near zero group-delay dispersion

Summary form only given. The operation of self-modelocked lasers continues to be the subject of intense experimental and theoretical study. Much physical insight into the dominant pulse-shaping mechanisms is obtained with near-zero cavity group delay dispersion (GDD), where deviations from soliton-like pulse shaping and effects of dispersive perturbations are evident. For example, experiments with reduced negative-GDD show third-order-dispersion induced dispersive wave components in the pulse spectra, and experiments with small positive-GDD show how gain dispersion stabilises self-phase modulation (SPM) resulting in rectangular spectra. In the paper, we report a new regime of near zero-GDD operation in a self-modelocked Ti:Sapphire laser, intermediate between dispersive-wave generation with negative-GDD, and rectangular spectra with positive-GDD. The results are in agreement with a model of intracavity four wave mixing (FWM) about the cavity zero-GDD wavelength (ZDW).