ABSTRACT
Polarizing beam splitters are typically made from birefringent crystals, but they can also be accomplished using a multilayer thin-film structure. The thin-film construction has the benefit of being adaptable to many different wavelengths as well as being compact. One common misconception arises from viewing the fields in thin films as rays instead of waves. The films are deposited on the base of a prism, and a second prism is used to sandwich the film structure such that the exit medium also has an index of 1.5. In this view, a tilted ray will travel a longer path through the film compared to a normally incident ray. In the wave treatment, the wave number k inside a film has two orthogonal components. One component is perpendicular to the films, and the other is parallel to the films.
