# Spatial solitons rays in periodic optical lattices

## TL;DR

This paper investigates the chaotic behavior of spatial soliton rays in periodically modulated optical media, using a new perturbative approach to relate the phenomena to a parametric driven pendulum model, confirming the nonlinear compensation of diffraction.

## Contribution

It introduces a novel perturbative method to analyze light ray chaos in modulated optical films, linking it to a pendulum analogy and extending understanding of soliton propagation in complex media.

## Key findings

- Chaotic regimes occur for soliton rays in periodic optical lattices.
- The propagation behavior aligns with a parametric driven pendulum model.
- Nonlinear effects compensate diffraction, matching eikonal law predictions.

## Abstract

The light ray of a spatial soliton in an optical film whose refractive index is smoothly modulated (wavelength much larger than the typical soliton width) in both spatial directions is shown to possess chaotic regimes for which the propagation is erratic. This is interpreted as a parametric driven pendulum, obtained by a new perturbative approach of the Maxwell equation. These findings are then demonstrated to compare well to the eikonal law of light ray propagation (nonlinearity compensates diffraction).