The Peregrine soliton — a wave localized in both space and time — is now observed experimentally for the first time by using femtosecond pulses in an optical fibre. The results give some insight into freak waves that can appear out of nowhere before simply disappearing.

/pdf/the-peregrine-soliton-in-nonlinear-fibre-optics-2shiem6is8.pdf

The Peregrine soliton in nonlinear fibre optics

The conventional definition of rogue waves in the ocean is that their heights, from crest to trough, are more than about twice the significant wave height, which is the average wave height of the largest one-third of nearby waves. When modeling deep water waves using the nonlinear Schr\"odinger equation, the most likely candidate satisfying this criterion is the so-called Peregrine solution. It is localized in both space and time, thus describing a unique wave event. Until now, experiments specifically designed for observation of breather states in the evolution of deep water waves have never been made in this double limit. In the present work, we present the first experimental results with observations of the Peregrine soliton in a water wave tank.

/pdf/rogue-wave-observation-in-a-water-wave-tank-1fu0j6iu4n.pdf

Rogue wave observation in a water wave tank.

The concept of parity-time symmetric systems is rooted in non-Hermitian quantum mechanics where complex potentials obeying this symmetry could exhibit real spectra. The concept has applications in many fields of physics, e.g., in optics, metamaterials, acoustics, Bose-Einstein condensation, electronic circuitry, etc. The inclusion of nonlinearity has led to a number of new phenomena for which no counterparts exist in traditional dissipative systems. Several examples of nonlinear parity-time symmetric systems in different physical disciplines are presented and their implications discussed.

Nonlinear waves in PT -symmetric systems

http://personalpages.to.infn.it/~onorato/publications_files/2013_Onorato_etal_PhysRep.pdf

Rogue waves and their generating mechanisms in different physical contexts

Rare events of extremely high optical intensity are experimentally recorded at the output of a mode-locked fiber laser that operates in a strongly dissipative regime of chaotic multiple-pulse generation. The probability distribution of these intensity fluctuations, which highly depend on the cavity parameters, features a long-tailed distribution. Recorded intensity fluctuations result from the ceaseless relative motion and nonlinear interaction of pulses within a temporally localized multisoliton phase.

/pdf/dissipative-rogue-waves-generated-by-chaotic-pulse-bunching-4cyoxua82r.pdf

Dissipative rogue waves generated by chaotic pulse bunching in a mode-locked laser

Observation of Rogue Waves.- Deterministic and Statistical Approaches for Studying Rogue Waves.- Quasi-Linear Wave Focusing.- Rogue Waves in Waters of Infinite and Finite Depths.- Shallow-Water Rogue Waves.- Conclusion.

Christian Kharif

Papers

Rogue Waves in the Ocean