Nonlinear Propagation in Optical Fibers With Gain Saturation and Gain Dispersion

There have been many developments in nonlinear propagation models in the past few decades. Especially, a form of such model has been developed to allow a standard ordinary differential equation (ODE) solver to be directly used for its solution. But such a model currently does not consider gain saturation and wavelength-dependent gain, which are very important in high-pulse-energy lasers. In this work, the directly-ODE-integrable nonlinear propagation equation is extended to include gain saturation and gain dispersion, which is then used to study maximum pulse energy limited by amplified spontaneous emission and minimum pulse width limited by gain narrowing in ultrafast fiber lasers in order to demonstrate these new capabilities.