Versatile full-vectorial finite element model for crossed gratings.

We demonstrate the accuracy of the finite-element method to calculate the diffraction efficiencies of an arbitrarily shaped crossed grating in a multilayered stack illuminated by an arbitrarily polarized plane wave under oblique incidence. The method has been validated by using classical cases found in the literature. Finally, to illustrate the independence of our method with respect to the shape of the diffractive object, we present the global energy balance resulting from the diffraction of a plane wave by a lossy thin torus crossed grating.