Thin Films in Optics

Abstract

In this paper we show how the optical response of a dielectric thin film, or stack of thin films (multilayer), can be evaluated. This subject has been studied by several people, particularly in the last decade, since the use of thin films in optics has many and varied applications. From the old antireflection film coating we go to high reflectance mirrors, beam splitters, interference filters, polarizers etc. Furthermore in recent years, with the wide development of the lasers, there has been a great effort on a new field which is known under the title of “integrated optics”. Its main goals are the design and construction of compact optical systems having the properties of some logical circuits that, until now, have been made with the technology of the integrated electronics. Examples of applications of integrated optics are: optical modulators, rotators, waveguides, etc., which are useful for telecommunications and computers. The field is very vast as one can imagine from the examples listed above and therfore it is not possible to cover it in this paper. Therefore we have confined ourselves to the foundations of light propagation in stratified media with particular attention to transverse and longitudinal propagation. These two aspects have been considered at first for the single film which will be described in the first part whereas multilayer systems will be considered in the second part. Application of several of these concepts can be found in the literature quoted here and, as far as the problem of filters and polarizers is concerned, in the paper of Prof. Pelletier.