We experimentally investigate the nonlinear reshaping of a continuous wave that leads to chirp-free and flat-top intense pulses or flaticons exhibiting strong temporal oscillations at their edges and a stable self-similar expansion upon propagation of their central region. This study was performed in the normal dispersion regime of a nonzero dispersion-shifted fiber and involved a sinusoidal phase modulation of the continuous wave. Our fiber optics experiment is analogous to considering the collision between oppositely directed currents near the beach, and it may open the way to new investigations in the field of hydrodynamics.

We analytically calculate and discuss the radio-frequency spectrum of the socalled Akhmediev breathers, a class of nonlinear solutions of the nonlinear Schrodinger equation that governs the propagation in a single mode optical fiber. We propose a practical application of ABs to the field of ultra-wideband pulse generation.