Directional decomposition and generalized-screen approximation for the scattering of electromagnetic waves in isotropic, frequency dependent media

The electromagnetic wavefield is decomposed into up- and downgoing constituents, which allows the introduction of the one-way wave operator. Transverse scattering is taken into account by a pseudodifferential operator, the vertical slowness operator. The actual computation of the one-way wave propagator is made feasible by the introduction of the so-called generalized-screen approximation of the vertical slowness symbol. The medium is defined in terms of a background medium and a perturbation. Such a contrast formulation induces a polyhomogenous series expansion of the vertical slowness symbol in both the magnitude and the smoothness of the medium perturbation; the addition of higher-order terms of the series expansion increases the accuracy of the one-way generalized-screen propagator. The medium parameters, dielectric permittivity and magnetic permeability, are described by Cole-Cole distributions to allow a realistic description of frequency dependent medium properties. These results are then cast into a family of fast numerical algorithms. We analyze the accuracy of the generalized-screen method in complex structures using synthetic models that exhibit significant multiple scattering. The generalized-screen method shows accuracy for wide-angle propagation as well as for the prediction of multi-pathing.