Control of spectral extreme events in ultrafast fibre lasers by a genetic algorithm

TL;DR

This paper demonstrates the active control of rogue wave events in ultrafast fibre lasers using a genetic algorithm, enabling precise triggering of extreme optical waves with significantly increased spectral intensity.

Contribution

It extends genetic algorithms to actively control and generate optical rogue waves in fibre lasers, a novel application in nonlinear optical systems.

Findings

Achieved spectral peak intensity 32.8 times above the rogue wave threshold.

Successfully controlled and triggered rogue wave events in a fibre laser cavity.

Confirmed spectral up- and down-shifting through numerical simulations.

Abstract

Extreme wave events or rogue waves (RWs) are both statistically rare and of exceptionally large amplitude. They are observed in many complex systems ranging from oceanic and optical environments to financial models and Bose-Einstein condensates. As they appear from nowhere and disappear without a trace, their emergence is unpredictable and non-repetitive, which make them particularly challenging to control. Here, we extend the use of genetic algorithms (GAs), which have been exclusively designed for searching and optimising stationary or repetitive processes in nonlinear optical systems, to the active control of extreme events in a fibre laser cavity. Feeding real-time spectral measurements into a GA controlling the electronics to optimise the cavity parameters, we are able to trigger wave events in the cavity that have the typical statistics of RWs in the frequency domain. This accurate control enables the generation of the optical RWs with a spectral peak intensity 32.8 times higher than the significant intensity threshold. A rationale is proposed and confirmed by numerical simulations of the laser model for the related frequency up- and down-shifting of the optical spectrum that are experimentally observed.