Submerged plane layered isotropic media: Properties of the scattering matrix eigenvalues with application to bilayers (L)

The plot of the transmission coefficient moduli cannot be used to analyze all the resonances of layered structures because of the overlapping of the resonances. A method using the scattering matrix eigenvalues is presented. It allows, first, to annihilate the overlapping and to recover the resonance positions and half-widths and second, to divide in two independent sets most of the resonances involved in symmetric structures as well as in nonsymmetric ones. Comparisons between the results provided by the method and those coming from the poles of the transmission coefficient agree. In many cases, the transition terms constitute a generalization of the transmission coefficients.