Modal dynamics in multimode optical fibers: An attractor of high-order modes

TL;DR

This paper explores how high-order modes in multimode optical fibers evolve towards a stable attractor, acting as a 'valve' that controls energy flow, with implications for nonlinear phenomena and secure communication applications.

Contribution

It reveals the existence of a high-order mode attractor in multimode fibers and demonstrates its role as an energy flow regulator using Lyapunov exponents.

Findings

High-order modes evolve to a stationary distribution.

The HOMs-attractor acts as a 'valve' controlling energy flow.

Transition points align with the threshold of the attractor.

Abstract

Multimode fibers (MMFs) support abundant spatial modes and involve rich spatiotemporal dynamics, yielding many promising applications. Here, we investigate the influences of the number and initial energy of high-order modes (HOMs) on the energy flow from the intermediate modes (IMs) to the fundamental mode (FM) and HOMs. It is quite surprising that random distribution of high-order modes evolves to a stationary one, indicating the asymptotic behavior of orbits in the same attraction domain. By employing the Lyapunov exponent, we prove that the threshold of the HOMs-attractor is consistent with the transition point of the energy flow which indiactes the HOMs-attracotr acts as a "valve" in the modal energy flow. Our results provide a new perspective to explore the nonlinear phenomena in MMFs, such as Kerr self-cleaning, and may pave the way to some potential applications, such as secure communications in MMFs.