Circular-Polarization-Based Reflection Scattering Measurements in Skin-Mimicking Media for Optical Glucose Sensing

Continuous glucose monitoring motivates the development of non-invasive optical sensing approaches. This study investigates polarization-resolved reflection scattering in simplified skin-mimicking phantoms using single-wavelength visible and near-infrared illumination. Linear and circular polarization are compared over glucose concentrations of 50–400 mg/dL at 450, 532, and 660 nm. Linear polarization yields correlations of R² = 0.78–0.95, whereas circular polarization achieves higher correlations of 0.93–0.99 and remains above 0.969 at 532 and 660 nm under pigment interference. A polarization-preservation ratio (PPR), derived from left- and right-hand circularly polarized intensities, is introduced to quantify polarization retention under multiple scattering.