Validity of the Kirchhoff approximation for the scattering of electromagnetic waves from dielectric, doubly periodic surfaces

M. FRANCO; M. BARBER; M. MAAS; O. BRUNO; F. GRINGS; E. CALZETTA

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION - (Print)

OPTICAL SOC AMER

Lugar: Washington; Año: 2017 vol. 34 p. 1 - 12

1084-7529

Accuracy of Kirchhoff approximation (KA) for rough-surface electromagnetic wave scattering is studied by comparisonwith accurate numerical solutions in the context of three-dimensional dielectric surfaces. The Kirchhofftangent plane approximation is examined without resorting to the principle of stationary phase. In particular, it isshown that this additional assumption leads to zero cross-polarized backscattered power, but not the tangentplane approximation itself. Extensive numerical results in the case of a bisinusoidal surface are presented fora wide range of problem parameters: height-to-period, wavelength, incidence angles, and dielectric constants.In particular, this paper shows that the range of validity inherent in the KA includes surfaces whose curvatureis not only much smaller, but also comparable to the incident wavelength, with errors smaller than 5% in totalreflectivity, thus presenting a detailed and reliable source for the validity of the KA in a three-dimensional fullypolarimetric formulation.