ADMITTANCE OF RUGATE FILTERS DERIVED FROM A 2X2 INHOMOGENEOUS MATRIX

Admittance diagrams are used to analyze qualitatively and quantitative ly the behavior of inhomogeneous thin films with an arbitrary refracti ve-index function. From this study it follows that one can treat the b ehavior of rugate filters by using the concept of effective refractive indices, which are associated with the phase integral in a simple way . These results are applied to the study of periodic systems, and, as expected, one can consider high and low effective refractive indices t o determine the important parameters of these stop bands. With these i deas it is possible that one can deal with rugate filters more closely as homogeneous periodic systems by taking advantage of the existing t heory.