Spatiotemporal Tracking of Persistent, Localized Speckles in Turbulent Atmospheric Propagation

TL;DR

This paper investigates how individual speckles in turbulent atmospheric light propagation evolve over space and time, revealing their fragmentation, localization, and persistence, which affect long-distance optical communication and sensing.

Contribution

It introduces a novel method for tracking individual speckles' spatiotemporal dynamics and quantifies their behavior under different turbulence conditions.

Findings

Larger beams fragment closer to the source, indicating less robustness to decoherence.

Speckles are spatially localized and persist over long distances.

Localization and persistence influence long-distance light statistics.

Abstract

Light propagation through turbulence produces speckles, whose ensemble behavior is typically characterized by snapshot intensity statistics. Here, we track the spatiotemporal evolution of individual speckles and quantify fragmentation, localization, and persistence under different diffraction and turbulence scales. Beam fragmentation coincides with complete spatial decorrelation defined by the magnitude-squared coherence. Fragmentation occurs closer to the source for larger beams, which indicates that smaller beams are more robust to decoherence. Subsequently, speckles are both spatially localized and persistent over distances significantly longer than their associated Rayleigh length. The combination of localization and persistence impacts the statistics of light relevant to their long-distance signaling and sensing.