title: Implementing the near- to far-field transformation in the finite-difference time-domain method.
abstract: When the finite-difference time-domain (FDTD) method is applied to light-scattering computations, the far fields can be obtained by means of integrating the near fields either over the volume bounded by the particle's surface or on a regular surface encompassing the scatterer. For light scattering by a sphere, the accurate near-field components on the FDTD-staggered meshes can be computed from the rigorous Lorenz-Mie theory. We investigate the errors associated with these near- to far-field transform methods for a canonical scattering problem associated with spheres. For a scatterer with a small refractive index, the surface-integral approach is more accurate than its volume counterpart for computation of the phase functions and extinction efficiencies; however, the volume-integral approach is more accurate for computation of other scattering matrix elements, such as P12, P32, and P43, especially for backscattering. If a large refractive index is involved, the results computed from the volume-integration method become less accurate, whereas the surface method still retains the same order of accuracy as in the situation for the small refractive index.
authors.affiliation: Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Peng-Wang
authors.initials: PW
authors.lastname: Zhai
authors.forename: Yong-Keun
authors.initials: YK
authors.lastname: Lee
authors.forename: George W
authors.initials: GW
authors.lastname: Kattawar
authors.forename: Ping
authors.initials: P
authors.lastname: Yang