Discovery of Soliton Self-Mode Conversion in Multimode Optical Fibers

TL;DR

This paper reports the discovery of a self-action nonlinear effect in multimode optical fibers, enabling complete frequency conversion of ultrashort soliton pulses between modes, with significant spectral translation and high peak power generation.

Contribution

It introduces a novel self-action nonlinear mechanism originating from quantum noise, enabling efficient mode-to-mode soliton conversion in large-mode-count fibers, expanding possibilities for ultrashort pulse generation.

Findings

Achieved ~70% spectral translation of the carrier frequency.

Generated Megawatt peak-power pulses in the 1300-nm window.

Discovered a fundamental role of intermodal group velocity dispersion in multimode nonlinear optics.

Abstract

Nonlinear optical wave propagation manifests in a multitude of frequencies generated from quantum-noise, and selecting desired nonlinear products usually requires seeding the medium with extraneous waves, employing spatial or spectral filters, or operation in resonant cavities. This is especially true for multimode systems because of their high density of states. Here we report the discovery of a self-action effect, originating from quantum noise, leading to complete nonlinear optical conversion of an ultrashort soliton pulse between two distinct, spatially coherent eigenmodes that are frequency-separated by one Raman Stokes shift. That systematic nonlinear spatial reconfiguration occurs in fibers with mode counts exceeding 10,000, which are often deemed to be chaotic, points to the fundamental role of intermodal group velocity dispersion in the selection rules for multimode nonlinear optics. We demonstrate wideband spectral translations of ~70% of the carrier frequency, and the generation of record, Megawatt peak-power pulses in the biologically crucial 1300-nm spectral window, directly out of a flexible optical fiber. More generally, this novel nonlinear coupling mechanism may be applied to fibers or on-chip waveguides, and facilitate, power-scalable spatially coherent, ultrashort pulse generation from the visible to the mid-IR.