Staggered-grid PSTD on local Fourier basis and its applications to surface tissue modeling

We introduce a high performance parallelization to the PSTD solution of Maxwell equations by employing the fast Fourier transform on local Fourier basis. Meanwhile a reformatted derivative operator allows the adoption of a staggered-grid such as the Yee lattice in PSTD, which can overcome the numerical errors in a collocated-grid when spatial discontinuities are present. The accuracy and capability of our method are confirmed by two analytical models. In two applications to surface tissue optics, an ultra wide coherent backscattering cone from the surface layer is found, and the penetration depth of polarization gating identified. Our development prepares a tool for investigating the optical properties of surface tissue structures.