Geometric parametric instability in periodically modulated GRIN multimode fibers

TL;DR

This paper investigates how periodic modulation of the core diameter in graded-index multimode fibers influences light propagation, revealing the induction of Moiré-like patterns that alter geometric parametric instability gain.

Contribution

It introduces a novel approach to control spatiotemporal dynamics in multimode fibers through periodic core diameter modulation, combining theoretical and numerical analysis.

Findings

Periodic modulation induces Moiré-like patterns.

Modulation modifies geometric parametric instability gain.

Control over light dynamics in multimode fibers achieved.

Abstract

We present a theoretical and numerical study of light propagation in graded-index (GRIN) multimode fibers where the core diameter has been periodically modulated along the propagation direction. The additional degree of freedom represented by the modulation permits to modify the intrinsic spatiotemporal dynamics which appears in multimode fibers. More precisely, we show that modulating the core diameter at a periodicity close to the self-imaging distance allows to induce a Moir\'{e}-like pattern, which modifies the geometric parametric instability gain observed in homogeneous GRIN fibers.