In optical telecommunication systems, different forms of optical filters are used. They are Fabry-Perot etalons, layers of thin films, fiber Bragg gratings, long period fiber gratings and directional couplers. To design optical filters numerical optimization techniques or other ad hoc methods are used, and a universally applicable tool as for the analog RLC filters or digital filters does not exist yet. However, these optical filters share the commonality of being modeled as a cascaded structure of orthogonal lattice sections, although they all operate under different physical principles. Consequently researchers tried to use the Schur recursion to analyze or design optical filters. In this talk, we shall discuss difficulties associated with the Schur recursion applied to optical filters, and suggest some possible remedies.