Near-field interactions and non-universality in speckle patterns produced by a point source in a disordered medium

TL;DR

This paper investigates the C_0 speckle correlation in disordered media, revealing its origin in near-field interactions and its potential for subwavelength sensing and imaging.

Contribution

It provides a theoretical and numerical analysis linking C_0 correlation to near-field interactions and local density of states fluctuations.

Findings

C_0 correlation arises mainly from near-field interactions.

C_0 is non-universal and sensitive to local environment.

Potential applications in subwavelength sensing and imaging.

Abstract

A point source in a disordered scattering medium generates a speckle pattern with non-universal features, giving rise to the so-called C_0 correlation. We analyze theoretically the relationship between the C_0 correlation and the statistical fluctuations of the local density of states, based on simple arguments of energy conservation. This derivation leads to a clear physical interpretation of the C_0 correlation. Using exact numerical simulations, we show that C_0 is essentially a correlation resulting from near-field interactions. These interactions are responsible for the non-universality of C_0, that confers to this correlation a huge potential for sensing and imaging at the subwavelength scale in complex media.