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

摘要

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