Modification of light transmission channels by inhomogeneous absorption in random media

TL;DR

This study numerically investigates how inhomogeneous absorption affects light transmission channels in highly scattering media, revealing that high transmission channels adapt by rerouting energy to minimize absorption losses.

Contribution

It provides new insights into the impact of spatially varying absorption on transmission eigenchannels and their ability to bypass absorbing regions in complex media.

Findings

High transmission channels reroute energy around absorbing regions in strong absorption regimes.

Inhomogeneous absorption results in broader transmission eigenvalue distributions.

Maximum transmission channels become more efficient at bypassing absorption with increasing absorption.

Abstract

Optical absorption is omnipresent and very often distributed non-uniformly in space. We present a numerical study on the effects of inhomogeneous absorption on transmission eigenchannels of light in highly scattering media. In the weak absorption regime, the spatial profile of a transmission channel remains very similar to that without absorption, and the effect of inhomogeneous absorption can be stronger or weaker than homogeneous absorption depending on the spatial overlap of the localized absorbing region with the field intensity maximum of the channel. In the strong absorption regime, the high transmission channels redirect the energy flows to circumvent the absorbing regions to minimize loss. The attenuation of high transmission channels by inhomogeneous absorption is lower than that by homogeneous absorption, regardless of the location of the absorbing region. The statistical distribution of transmission eigenvalues in the former becomes broader than that in the latter, due to a longer tail at high transmission. Since the maximum transmission channel is the most efficient in bypassing the absorbing region, the ratio of its transmittance to the average transmittance increases with absorption, eventually exceeds the ratio without absorption.