Monte Carlo simulation of sphere-cylinder scattering medium for Double Stokes-Mueller polarimetry

Monte Carlo simulation offers significant advantages in the prediction of second harmonic generation polarization photon propagation behavior. The existing Monte Carlo (MC) simulation models, which primarily focus on sphere scattering particles, neglect the modeling of collagen fibers, which is the primary medium to generate the second harmonic signals. Additionally, the impact of structural changes in cylindrical collagen fibers on the nonlinear susceptibility ratio has not been sufficiently explored. In this paper, we propose an MC simulation of sphere-cylinder scattering mediums based on the DSMP. The MC simulation is divided into a three-layer structure consisting of sphere-cylinder-sphere configurations, based on the optical process of second harmonic generation. Furthermore, we analyze the impact of model parameter variations on the second-order nonlinear susceptibility. The results indicate that the augmentation of the second-order susceptibility ratio is observed when increasing the radius of sphere scattering models or decreasing their thickness. The increase in the radius of the cylinder scattering model and variation of orientation leads to an increase in the second-order susceptibility ratio R. Particularly, the orientation has a significant impact on the R value. This study provides valuable insights for the diagnosis of tissue abnormalities.