Enhancing reflected light filtration of photoelectronic detection system using polarization gating in scattering media

Photoelectronic technology has found extensive application due to its non-invasiveness, compact structure, and low cost. However, in semi-transparent media, the detection system based on reflection structure indiscriminately receives reflection light from different depths, resulting in the masking of target signals and a decrease in signal quality. To address this issue, selecting reflected light at different depths through polarization gates is an effective way. In this study, we analyzed a polarization gate-semi-infinite medium scattering model and investigated the impact of various factors on the reflected light filtering capability of the polarization gate, through Monte Carlo simulations and polystyrene microsphere scattering experiments. We found that the polarization gate can achieve a more effective control effect on the high polarization area on the reflective surface. Furthermore, the signal-to-noise ratio of the photoplethysmography sensor with an orthogonally polarized gate was improved from 0.72 to 2.36 dB. In other words, the polarization gate offers new insights into signal optimization through a structural design, which facilitates the development of wearable, low-power, and robust physiological signal measurement systems in the future.