title: Solutions of Maxwell's equations in presence of lamellar gratings including infinitely conducting metal.
abstract: Modal methods often used to model lamellar gratings that include infinitely or highly conducting metallic parts encounter numerical instabilities in some situations. In this paper, the origin of these numerical instabilities is determined, and then a stable algorithm solving this problem is proposed. In order to complete this analysis, the different geometries that can be handled without numerical instabilities are clearly defined. Numerical tests of the exact modal method implemented with the proposed solution are also presented. A test of convergence shows the efficiency of the method while the comparison with the fictitious sources method shows its accuracy.
authors.affiliation: Institut Fresnel-CNRS (UMR 6133), faculté de Saint Jérôme, 13397 Marseille cedex 20, France. boris.gralak@fresnel.fr
authors.forename: Boris
authors.initials: B
authors.lastname: Gralak
authors.forename: Raphaël
authors.initials: R
authors.lastname: Pierre
authors.forename: Gérard
authors.initials: G
authors.lastname: Tayeb
authors.forename: Stefan
authors.initials: S
authors.lastname: Enoch