Self-organized instability in graded-index multimode fibres

TL;DR

This paper investigates the complex spatiotemporal dynamics in graded-index multimode fibres, revealing a universal unstable attractor driven by intermodal interactions, disorder, and nonlinearity, with implications for telecommunications and complexity science.

Contribution

It introduces a comprehensive study of MMFs where disorder, nonlinearity, and dissipation are all considered, uncovering a universal unstable attractor and self-organization phenomena.

Findings

Observation of spatial beam-cleaning before modulation instability

Identification of a universal unstable attractor in MMFs

Disorder enhances nonlinear processes in multimode fibres

Abstract

Multimode fibres (MMFs) are attracting interest for complex spatiotemporal dynamics, and for ultrafast fibre sources, imaging and telecommunications. This new interest is based on three key properties: their high spatiotemporal complexity (information capacity), the important role of disorder, and complex intermodal interactions. To date, phenomena in MMFs have been studied only in limiting cases where one or more of these properties can be neglected. Here we study MMFs in a regime in which all these elements are integral. We observe a spatial beam-cleaning process preceding spatiotemporal modulation instability. We show that the origin of these processes is a universal unstable attractor in graded-index MMFs. Both the self-organization of the attractor, as well as its instability, are caused by intermodal interactions characterized by cooperating disorder, nonlinearity and dissipation. The demonstration of a disorder-enhanced nonlinear process in MMF has important implications for telecommunications, and the multifaceted complexity of the dynamics showcases MM waveguides as ideal laboratories for many topics and applications in complexity science.