Raman solitons in waveguides with simultaneous quadratic and Kerr nonlinearities

TL;DR

This paper investigates how Raman effects influence two-component solitons in waveguides with quadratic and Kerr nonlinearities, deriving analytical expressions and confirming them with simulations, revealing potential instabilities and power transfer phenomena.

Contribution

It provides the first analytical treatment of Raman-induced shifts in two-component quadratic-Kerr solitons and explores their stability and power transfer dynamics.

Findings

Raman shifts match well with simulations

Raman effects can destabilize solitons near their existence boundary

Power transfer to second harmonic can lead to single-component Kerr solitons

Abstract

We analyse Raman-induced self-frequency shift in two-component solitons supported by both quadratic and cubic nonlinearities. Treating Raman terms as a perturbation, we derive expressions for soliton velocity and frequency shifts of the fundamental frequency and second harmonic soliton components. We find these predictions compare well with simulations of soliton propagation. We also show that Raman shift can cause two-component solitons to approach the boundary of their own existence and subsequently trigger soliton instabilities. In some cases these instabilities are accompanied by an almost complete transfer of power to the second harmonic, and emergence of a single-component Kerr solitonic pulse.