Study of polarization evolution in phantom tissues with ultrafast optics techniques: Monte Carlo simulations and experiments

This paper presents our study results of polarized short pulse transmission through phantom tissues made of polystyrene particle solutions with various concentrations and particle sizes. To improve the quality of optical imaging using an ultrafast light source, study is required to fully understand the evolution of the polarization state in the sample, as well as the time- and polarization-dependent distributions of optical intensity exiting from samples. Temporal profiles of the Stokes vectors and the degree of polarization are measured experimentally. The results agree well with those resulting from Monte Carlo simulations. Analyses based on the Stokes-Mueller formalism show that the first scattering event determines the spatial patterns of the transmitted Stokes vectors. When a detected area at the output surface of the sample is symmetric about the incident beam, the temporal profile of transmittance is independent of the incident polarization state. The linear relationship between the average order of scatters and the light propagation time can be used to explain the exponential decay of the degree of polarization and the inversely proportional relationship between the FWHM of the degree of polarization and the scatterer concentration.