Transverse localization of transmission eigenchannels

TL;DR

This paper reveals that transmission eigenchannels in diffusive media exhibit transverse localization, which is crucial for understanding wave transport and improving imaging and energy transfer in turbid environments.

Contribution

It uncovers the transverse localization of transmission eigenchannels in diffusive slabs, a property previously poorly understood, combining theoretical insights and experimental evidence.

Findings

Transmission eigenchannels have localized incident and outgoing profiles.

Localization arises from reciprocity, mode coupling, and wave correlations.

Experimental signatures of localization are observed despite finite illumination.

Abstract

Transmission eigenchannels are building blocks of coherent wave transport in diffusive media, and selective excitation of individual eigenchannels can lead to diverse transport behavior. An essential yet poorly understood property is the transverse spatial profile of each eigenchannel, which is critical for coupling into and out of it. Here, we discover that the transmission eigenchannels of a disordered slab possess localized incident and outgoing profiles, even in the diffusive regime far from Anderson localization. Such transverse localization arises from a combination of reciprocity, local coupling of spatial modes, and nonlocal correlations of scattered waves. Experimentally, we observe signatures of such localization despite finite illumination area. Our results reveal the intrinsic characteristics of transmission eigenchannels in the open slab geometry, commonly used for applications in imaging and energy transfer through turbid media.