Random media characterization using the analysis of diffusing light data on the basis of an effective medium model

Area of Science:

• * Optics and Photonics
• * Condensed Matter Physics
• * Materials Science

Background:

• * Understanding light transport in dense scattering media is crucial for applications in imaging, sensing, and materials science.
• * Previous studies often require prior knowledge of scattering particle properties, limiting their applicability.
• * Dense random media like rutile powder and polyball suspensions exhibit complex light scattering behaviors.

Purpose of the Study:

• * To develop and apply a novel technique for retrieving transport parameters of scattering media.
• * To investigate the wavelength-dependent transport properties of rutile powder and polyball suspensions.
• * To determine the transport mean free path (l*) and effective refractive index (n(ef)) without a priori assumptions.

Main Methods:

• * Experimental analysis of coherent backscattering, diffuse transmittance, and low-coherence interferometry.
• * Development of a retrieval technique for transport parameters (l* and n(ef)).
• * Measurements conducted in the visible and near-infrared spectrum.

Main Results:

• * The developed technique successfully evaluated transport mean free path and effective refractive index.
• * A notable decrease in the localization parameter (2πn(ef)l*/λ₀) was observed for rutile samples as wavelength decreased.
• * The localization parameter approached ~2.6 at 473 nm, linked to strong scattering near the first Mie resonance.

Conclusions:

• * The study presents a robust method for characterizing light transport in dense scattering media.
• * The observed drop in the localization parameter highlights the significant impact of Mie resonance on optical properties.
• * Findings provide essential data for understanding and manipulating light propagation in complex materials.