Diffractive resonant radiation emitted by spatial solitons in waveguide arrays: towards a spatiotemporal supercontinuum generation

TL;DR

This paper investigates how spatial solitons in waveguide arrays emit diffractive resonant radiation, leading to supercontinuum generation with controllable directionality, by combining analytical and numerical methods.

Contribution

It introduces a phase matching condition for resonant radiation in waveguide arrays and demonstrates wavenumber-supercontinuum generation and soliton self-wavenumber shift compensation.

Findings

Phase matching condition matches simulations.

Wavenumber-supercontinuum generation observed.

Control of supercontinuum directionality demonstrated.

Abstract

We study analytically and numerically a kind of diffractive resonant radiation emitted by spatial solitons, which is generated in waveguide arrays with Kerr nonlinearity. The phase matching condition between soliton and radiation is derived and agrees well with direct pulse propagation simulations. The folded dispersion due to the Brillouin zone leads to a peculiar anomalous soliton recoil that we describe in detail. A linear potential applied across the array generates the analogue of the Raman self-frequency shift in optical fibers, only now applied to the wavenumber. We demonstrate that it is possible to mimic closely temporal fiber-optical dynamics, unveiling the new effects of wavenumber-supercontinuum generation and the compensation of the 'soliton self-wavenumber shift' by the emitted diffractive radiation. This work paves the way for designing unique optical devices that generate spectrally broad supercontinua with a controllable directionality.