Use of the theory of coupled waves for constructing multilayer optical coatings

A general numerical method is proposed for constructing multilayer optical coatings without using the basic structure. The possibility of application of the theory of coupled waves for describing optical coatings with a large difference in the values of the refractive index is demonstrated. As design parameters, the coefficients of harmonic expansion of the required functions n(x) are used, which makes it possible to produce local variations in a certain spectral region. The method is quite pictorial. An example of application of this method for calculating a broadband divider is considered.