Physical origin of higher-order soliton fission in nanophotonic semiconductor waveguides

TL;DR

This paper investigates the physical mechanisms behind higher-order soliton fission in nanophotonic semiconductor waveguides, revealing the dominant roles of nonlinear loss and free-carrier dispersion in different waveguide types.

Contribution

It provides experimental and simulation evidence clarifying the roles of nonlinear loss and free-carrier effects in soliton fission within semiconductor waveguides.

Findings

Nonlinear loss dominates in wire waveguides.

Free-carrier dispersion dominates in photonic crystal waveguides.

The study advances understanding of supercontinuum generation in integrated photonics.

Abstract

Supercontinuum generation in Kerr media has become a staple of nonlinear optics. It has been celebrated for advancing the understanding of soliton propagation as well as its many applications in a broad range of fields. Coherent spectral broadening of laser light is now commonly performed in laboratories and used in commercial white light sources. The prospect of miniaturizing the technology is currently driving experiments in different integrated platforms such as semiconductor on insulator waveguides. Central to the spectral broadening is the concept of higher-order soliton fission. While widely accepted in silica fibers, the dynamics of soliton decay in semiconductor waveguides is yet poorly understood. In particular, the role of nonlinear loss and free carriers, absent in silica, remains an open question. Here, through experiments and simulations, we show that nonlinear loss is the dominant perturbations in wire waveguides, while free-carrier dispersion is dominant in photonic crystal waveguides.