A full vectorial model for pulse propagation in emerging waveguides with subwavelength structures part I: Kerr nonlinearity

TL;DR

This paper introduces a comprehensive vectorial model for nonlinear pulse propagation in waveguides with subwavelength structures, highlighting the importance of the z-component of guided modes and providing revised definitions of key parameters.

Contribution

It develops a generalized full vectorial model that accurately describes nonlinear pulse propagation in complex waveguides with subwavelength features, incorporating the z-component of modes.

Findings

The z-component of guided modes is crucial in these structures.

Revised definitions of nonlinear coefficient $$ and $A_{eff}$ differ significantly from standard models.

Predicted a factor of ~2 higher nonlinear coefficient $$ for emerging waveguides.

Abstract

The propagation of pulses through waveguides with subwavelength features, inhomogeneous transverse structure, and high index contrast cannot be described accurately using existing models in the presence of nonlinear effects. Here we report the development of a generalised full vectorial model of nonlinear pulse propagation and demonstrate that, unlike the standard pulse propagation formulation, the z-component of guided modes plays a key role for these new structures, and results in generalised definitions of the nonlinear coefficient $\gamma,$ $A_{eff}$, and mode orthognality. While new definitions reduce to standard definitions in some limits, significant differences are predicted, including a factor of $\sim2$ higher value for $\gamma$, for emerging waveguides and microstructured fibers.