  Nanocomposites with tailored optical properties can provide a new degree of
freedom for optical design. However, despite their potential these materials
remain unused in bulk applications. Here we investigate the conditions under
which they can be used for optical applications using Mie theory, effective
medium theories, and numerical simulations based on the finite element method.
We show that due to scattering different effective medium regimes have to be
distinguished, and that bulk materials can only be realized in a specific
parameter range. Our analysis also enables us to quantify the range of validity
of different effective medium theories, and identify design rules on how the
free material parameters should be adjusted for specific applications.
