FDTD can be used to simulate light scattering in the presence of wavelength scale and sub-wavelength scale geometries. Since the scattering intensity is usually very weak compared to the illumination, a differential method is often used. The total field scattered field method (TFSF) is a convenient technique to get the scattered field, which can remove the mirror reflection.

The simulation methodology can be very different depending on whether one is interested in simulating light scattering from standalone particles, particles on a substrate, or light scattering from a surface with nanoscale structures:

Standalone particles

For standalone objects such as particles suspended in a fluid, the typical quantity of interest is the absorption/scattering cross sections. We may also want to look at the near field enhancement around the particles, as well as the far field angular distribution.

Particles and defects on a surface

For particles and defects on a substrate, we often want to study light scattering into specific regions in the far field, and calculate results such as the differential scattering cross section. The degree of circular polarization can be also calculated using far field monitors.

Rough surfaces

A surface with nanoscale structure can be characterized with a bidirectional scattering distribution function (BSDF). This function relates the intensity of an incoming ray to an outgoing ray for all angles of incidence and reflection/transmission.

•Construct and parametrized complex 3D geometry using structure groups

•Use Lumericalâ€™s multi-coefficient materials to accurately model highly dispersive materials such as metals.

•Obtain accurate broadband results at multiple wavelengths in a single simulation

•Use a large variety of illumination conditions, such as unpolarized light, circularly polarized light or a dark field beam source

•Use a total field/scattered field source to calculate the absorption and scattering cross section of a particle.

•Calculate the bidirectional scattering distribution function for a rough surface.

•Use a fully vectorial far field calculator to determine the amount of light scattered into various regions of the far field.

•Lumericalâ€™s conformal mesh technology can provide sub-mesh cell modeling accuracy important for resolving the shape of wavelength and sub-wavelength scale geometry

•Built-in parameter sweep and optimization algorithms make it easy to analyze and optimize parameterized designs

## Solvers |
Description |

FDTD |
Cross section calculation: PSL and CU sphere scattering |

FDTD |
Determination of feature size correlated to a strong modulated signal: DVD surface |

FDTD |
Study scattering from isolated small particles on a surface: Defect scattering and detection |

FDTD |
Examine a surface with nanoscale structure: BSDF |

FDTD |