Optical Properties of Materials

In this article, the optical properties of macroscopic materials are described, basing only on classical arguments. Starting from Maxwell’s equations in a medium, the propagation of electromagnetic (em) waves in isotropic, linear, and homogeneous materials is treated. To this aim, complex macroscopic quantities as the dielectric function, the optical conductivity, and the refractive index are introduced, together with the dispersion relations that they obey. Some hints at their extensions to anisotropic and nonlinear materials are given.