Slabs

You can calculate fairly general scattering by slabs using discrete dipole approximation code DDSCAT (http://ddscat.com/) using its periodic particles option.

Barber and Hill slab code. A computer program from the text, Light Scattering by Particles: Computational Methods by P.W. Barber and S.C. Hill, may be used to calculate the reflected, transmitted, and internal intensities for a finite-thickness slab illuminated by a plane wave incident perpendicular to the surface.