Speckle instability: coherent effects in nonlinear disordered media

TL;DR

This paper numerically studies speckle patterns in nonlinear disordered media, revealing dynamical instability and chaos influenced by interference effects, with implications for understanding wave behavior in complex systems.

Contribution

It demonstrates the emergence of dynamical instability and chaos in speckle patterns due to nonlinearity and disorder, highlighting the role of interference effects and scaling laws.

Findings

Dynamical instability appears in the weak localization regime.

A scaling law governs the instability thresholds.

Coherent backscattering persists even in chaotic regimes.

Abstract

We numerically investigate the properties of speckle patterns formed by nonlinear point scatterers. We show that, in the weak localization regime, dynamical instability appears, eventually leading to chaotic behavior of the system. Analysing the statistical properties of the instability thresholds for different values of the system size and disorder strength, a scaling law is emphasized. The later is also found to govern the smallest decay rate of the linear system, putting thus forward the crucial importance of interference effects. This is also underlined by the fact that coherent backscattering is still observed even in the chaotic regime.