Exploring the dynamics of the Kelvin-Helmoltz instability in paraxial fluids of light

TL;DR

This paper investigates Kelvin-Helmoltz instability in paraxial fluids of light, revealing vortex sheet formation, quantized vortices, and characteristic energy spectra, advancing understanding of turbulence and related phenomena in optical quantum fluid analogues.

Contribution

It introduces a detailed study of Kelvin-Helmoltz instability in paraxial light fluids, combining numerical and experimental insights into vortex dynamics and energy spectra.

Findings

Vortex sheet formation observed experimentally and numerically.

Quantized vortices determined by initial conditions.

Power-law behavior in kinetic energy spectrum linked to vortex structures.

Abstract

Paraxial fluids of light have recently emerged as promising analogue physical simulators of quantum fluids using laser propagation inside nonlinear optical media. In particular, recent works have explored the versatility of such systems for the observation of two-dimensional quantum-like turbulence regimes, dominated by quantized vortex formation and interaction that results in distinctive kinetic energy power laws and inverse energy cascades. In this manuscript, we explore a regime analogue to Kelvin-Helmoltz instability to look into further detail the qualitative dynamics involved in the transition from smooth laminar flow to turbulence at the interface of two fluids with distinct velocities. Both numerical and experimental results reveal the formation of a vortex sheet as expected, with a quantized number of vortices determined by initial conditions. Using an effective length transformation scale we get a deeper insight into the vortex formation phase, observing the appearance of characteristic power-laws in the incompressible kinetic energy spectrum that are related to the single vortex structures. The results enclosed demonstrate the versatility of paraxial fluids of light and may set the stage for the future observation of distinct classes of phenomena recently predicted to occur in these systems, such as radiant instability and superradiance.