Conical diffraction by multilayer gratings: a recursive integral equation approach. (English) Zbl 1289.78005

Schmidt, Gunther

Appl. Math., Praha 58, No. 3, 279-307 (2013).

The author treats the solution of a multilayer diffraction gratings problem using a boundary value method.
The optical device is composed of an arbitrary number of different material layers. The interfaces between the layers are assumed to be non-interacting, possible non-smooth, periodic in \(x\)-direction, and translation invariant in \(z\)-direction. The material parameters, the permittivity \(\varepsilon \) and the permeability \(\mu \), can be complex values, that means, also optical metamaterials are included. Considered is the so-called conical or off-plane diffraction, where the direction of the incident wave is not orthogonal to the \(z\)-axis.
The author starts with a short history of the latest progress in the numerical methods for this problem. Based on the papers [ D. Maystre, ” A new general integral theory for dielectric coated gratings”, J. Opt. Soc. Am. 68, 490–495 (1978)], [L. I. Goray and G. Schmidt, J. Opt. Soc. Am. A 27, 585–597 (2010)], and [G. Schmidt and B. H. Kleemann, J. Mod. Opt. 58, No. 5–6, 407–423 (2011, Zbl 1221.78050)] the recursive algorithm, the discretization method, and the analysis of the method, respectively, are described.
Starting from the time-harmonic Maxwell equations the scattering problem is described by a system of Helmholtz equations with piecewise constant coefficients including special transmission conditions at the interfaces of the layers. Applying direct and indirect boundary integral methods gives a system of \(2N \times 2N\) singular integral equations, where \(N\) is the number of interfaces. A recursive procedure is presented that treats on each step the problem for one of the interfaces with \(2 \times 2\) operator matrices allowing to solve the problem on a standard personal computer.
Analyzing the algorithm necessary and sufficient conditions for the applicability of the method are formulated in proved theorems. The equations are unique solvable if and only if the matrix operator is invertible. Especially, the solution is unique if the imaginary parts of the material parameters \(\varepsilon \) and \(\mu \) are positive.

Reviewer: Georg Hebermehl (Berlin)

MSC:

78A45	Diffraction, scattering
78M15	Boundary element methods applied to problems in optics and electromagnetic theory
45E05	Integral equations with kernels of Cauchy type
35J05	Laplace operator, Helmholtz equation (reduced wave equation), Poisson equation
65R20	Numerical methods for integral equations

Keywords:

diffraction; periodic structure; multilayer grating; singular integral formulation; recursive algorithm

Citations:

Zbl 1221.78050

References:

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