Phase Singularity Diffusion

TL;DR

This paper investigates the movement of phase singularities in speckle patterns of transmitted waves through random media, revealing their diffusive behavior and proposing a method to characterize dynamic material systems.

Contribution

It introduces a novel approach to analyze phase singularity diffusion and relates it to photon diffusion, enabling characterization of dynamic systems.

Findings

Phase singularities diffuse linearly with frequency shift.

The product of singularity and photon diffusion coefficients relates to sample length.

Method provides a new way to characterize dynamic materials.

Abstract

We follow the trajectories of phase singularities at nulls of intensity in the speckle pattern of waves transmitted through random media as the frequency of the incident radiation is scanned in microwave experiments and numerical simulations. Phase singularities are observed to diffuse with a linear increase of the square displacement with frequency shift. The product of the diffusion coefficient of phase singularities in the transmitted speckle pattern and the photon diffusion coefficient through the random medium is proportional to the square of the effective sample length. This provides the photon diffusion coefficient and a method for characterizing the motion of dynamic material systems.