Angular Momentum Supercontinuum from Fibre Rings

TL;DR

This paper demonstrates the generation of broadband, coherent light with optical angular momentum using a ring array of coupled optical fibres, revealing new dynamics of soliton fission and resonant radiation influenced by lattice dispersion and twisting.

Contribution

It introduces a novel method for generating supercontinua with angular momentum in fibre rings, highlighting the effects of coupling and twisting on the supercontinuum properties.

Findings

Soliton fission breaks azimuthal symmetry in fibre rings.

Resonant radiation can occur without higher order dispersion.

Twisting the fibre array manipulates angular momentum and resonant frequencies.

Abstract

Broadband, coherent light carrying optical angular momentum is of potential utility for a variety of classical and quantum communication applications, but at present few such sources exist. We study the generation of supercontinua in a ring array of coupled optical fibres. Short pulses carrying discrete angular momentum undergo soliton fission, spontaneously breaking azimuthal symmetry. This results in a train of pulses with a broadband frequency spectrum as well as a non-trivial angular momentum distribution. These spatio-temporal solitary waves, localised around a single fibre core, emit an unusual form of resonant radiation which can be present even in the absence of intrinsic higher order dispersion, being induced by the lattice dispersion of the ring array. We explore how the coupling properties between fibre cores affect the resulting supercontinuum, in particular how mildly twisting the array can effectively manipulate its angular momentum content and resonant frequencies through the induced Peierls phase.