Transmission ellipsometry of anisotropic substrates and thin films at oblique incidence. Handling multiple reflections

Transmission ellipsometry is a technique that is very sensitive to the anisotropy of a material. At large angles of incidence it is also very sensitive to the change of the refractive index at the interfaces. This work applies Berreman's 4 × 4 algebraic descriptions of light transmission in layered bianisotropic media. When the optical response of thick layers is modeled, the calculated spectra show narrow oscillations due to the interference of the multiple reflections that are typically not observed experimentally. We present an incoherent treatment of the multiple reflections that avoids this problem. A method that allows a straightforward simplification of the 4 × 4 to 2 × 2 matrices is also presented for systems where multiple reflections can be disregarded.