Extracting geometrical information of closely packed random media from multiply scattered light via a cross-correlation analysis

We have implemented a two-dimensional (2-D) pseudospectral time-domain (PSTD) numerical solution of Maxwell's equations to calculate the total scattering cross-section (TSCS) spectrum of a macroscopic, closely packed, random medium consisting of dielectric cylinders. Results reported in this letter show that a TSCS spectral signature is identified, revealing structural information of the random medium. Furthermore, by means of the proposed cross-correlation analysis, the diameter of constituent cylinders within a closely packed cluster can be determined. On a broader perspective, based on first principles, our research findings may lead to a better understanding of the coherent interference effect of light scattering by closely packed random media. Specifically, we show that, microscopic structural information of the random medium can be determined from the forward, multiply scattered light, even for optically thick, closely packed random media, with scatterers spaced less than a single wavelength apart.