Self-similar propagation of optics pulses in fibers with positive quartic dispersion

We study the propagation of ultrashort pulses in optical fiber with gain and positive (or normal) quartic dispersion by self-similarity analysis of the modified nonlinear Schrodinger equation. We find an exact asymptotic solution, corresponding to a triangle-like T-4/3 intensity profile, with a T-1/3 chirp, which is confirmed by numerical simulations. This solution follows different amplitude and width scaling compared to the conventional case with quadratic dispersion. We also suggest, and numerically investigate, a fiber laser consisting of components with positive quartic dispersion that emits quartic self-similar pulses. (C) 2020 Optical Society of America