The application of non-empirical effective medium theory (extended Maxwell-Garnett) to describe composite mixtures of spherical inclusions within a host continuum has been presented. The structures are composites of two different kinds of non-overlapping spheres, one made from a high refractive index non-plasmonic material and the other from a Drude-like material. Frequency-dependent complex dielectric function and refractive index of ZnS/Si and ZnO/Si composites have been calculated in the terahertz regime. The mentioned nano-structured composites also exhibit unique optical properties due to the phenomenon known as surface plasmon resonance (SPR).
