Abstract
Filtering of photonic signals of a certain frequency while suppressing all the others of a specific band for both electromagnetic signal polarizations, becomes possible with a single dielectric layer by properly engineering the occurred Fabry-Perot interference. Analytical formulas for combinations of cavity size, material texture and incoming angle are given so that the filtering purpose is optimally served. In this way, inverse design for a simple class of optical setups is rigorously performed and, if the employed medium is very dense and the working band narrow enough, sharp filters with increased frequency selectivity are obtained.