Effect of Dependent Scattering on Light Absorption in Highly Scattering Random Media

TL;DR

This paper investigates how dependent scattering affects light absorption in highly scattering random media, revealing deviations from traditional models and proposing a corrected theoretical approach for better accuracy.

Contribution

It introduces a quasi-crystalline approximation-based model to account for dependent scattering effects, improving predictions of light absorption in disordered media.

Findings

Deviations between ISA-RTE and full-wave methods increase with scatterer density.

The proposed QCA-based model aligns better with numerical simulations.

Dependent scattering significantly influences light absorption in highly scattering media.

Abstract

The approximate nature of radiative transfer equation (RTE) leads to a bunch of considerations on the effect of "dependent scattering" in random media, especially particulate media composed of discrete scatterers, in the last a few decades, which usually indicates those deviations RTE (combined with ISA) lead to from experimental and exact numerical results due to electromagnetic wave interference. Here we theoretically and numerically demonstrate the effect of dependent scattering on absorption in disordered media consisting of highly scattering scatterers. By making comparison between the independent scattering approximation-radiative transfer equation (ISA-RTE) and the full-wave coupled dipole method (CDM), we find that deviations between the two methods increase as scatterer density in the media increases. The discrepancy also grows with optical thickness. To quantitatively take dependent scattering effect into account, we develop a theoretical model using quasi-crystalline approximation (QCA) to derive dependent-scattering corrected radiative properties, based on the path-integral diagrammatic technique in multiple scattering theory. The model results in a more reasonable agreement with numerical simulations. The present work has profound implications for the coherent scattering physics in random media with absorption, correctly modeling light absorptance in random media and interpreting the experimental observations in various applications for random media such as solar energy concentration, micro/nanofluids, structural color generation, etc.