Rogue wave generation by inelastic quasi-soliton collisions in optical fibres

Optical “rogue” waves are rare and very high intensity pulses of light that occur in optical devices such as communication fibers. They appear suddenly and can cause transmission errors and damage in optical communication systems. Indeed, the physics governing their dynamics is very similar to “monster” or “freak” waves on the Earth’s oceans, which are known to harm shipping. It is therefore important to characterize rogue wave generation, dynamics and, if possible, predictability. Here we demonstrate a simple cascade mechanism that drives the formation and emergence of rogue waves in the generalized non-linear Schrödinger equation with third-order dispersion. This generation mechanism is based on inelastic collisions of quasi-solitons and is well described by a resonant-like scattering behaviour for the energy transfer in pair-wise quasi-soliton collisions. Our theoretical and numerical results demonstrate a threshold for rogue wave emergence and the existence of a period of reduced amplitudes — a “calm before the storm” — preceding the arrival of a rogue wave event. Comparing with ultra-long time window simulations of 3.865 × 106ps we observe the statistics of rogue waves in optical fibres with an unprecedented level of detail and accuracy, unambiguously establishing the long-ranged character of the rogue wave power-distribution function over seven orders of magnitude.