Linear Optics

Abstract

Understanding now the meaning of the complex refractive index for the transmission of electromagnetic radiation through a dielectric material, it is practical and also necessary to discuss the transition of the radiation from one medium with the refractive index $\tilde{n}_1$ into another medium with the refractive index $\tilde{n}_2$. The physical separation is called the interface between two media. Contrary to radiation propagating only through one dense medium where we saw that no radiation is scattered backwards, now we have to allow the back-scattering, the so-called reflection at boundaries. We will start here with non-absorbing dielectrics, meaning that the refractive index is purely real $\tilde{n}=n$.