Born-Padé approach to electromagnetic scattering in complex one-dimensional inhomogeneous slabs

Perturbation theory is applied to one-dimensional scattering systems consisting of a general class inhomogeneous and isotropic slabs having size $L$ described by the relative permittivity $\varepsilon(z) = 1 + \alpha \chi(z)$, where $\chi(z)$ electric susceptibility $\alpha$ perturbation parameter. The transmitted reflected amplitudes are shown be written as Born series in powers Pad\'e approximants used obtain analytical results with high arbitrary degree accuracy. approach very can handle oblique incidence. Examples given for transmission reflection plane waves interacting Hermitian non-Hermitian structures known unknown exact solutions.