Numerical analysis of scattering from echelette grating  Smoothing process on modematching method
Abstract
The modematching method is a general numerical method for diffraction problems in which the modal expansion of electromagnetic fields is matched to the boundary condition, as in the case of Dirichlettype boundary condition. However, the difficulty arises in deriving an accurate solution for Neumanntype problems where the electric vector is polarized in the direction perpendicular to grooves (Hpolarization). An infinitely long grating consisting of a perfect conductor with an arbitrary cross section is considered, assuming that the grating has a period one in the xdirection and is uniform in the zdirection. A smoothing procedure is proposed in which the modal expansion is matched to the boundary condition via an indefinite integral. This procedure is able to suppress the spectral spread and to analyze the problem of diffraction from an echelette grating. Numerical results indicate the problem of diffraction from a grating can be analyzed with sufficient accuracy even for the Hpolarization by adopting the new smoothing technique.
 Publication:

Electronics Communications of Japan
 Pub Date:
 March 1977
 Bibcode:
 1977JElCo..60...82Y
 Keywords:

 Echelette Gratings;
 Electromagnetic Scattering;
 Numerical Analysis;
 Propagation Modes;
 Smoothing;
 Boundary Conditions;
 Boundary Value Problems;
 Diffraction;
 Dirichlet Problem;
 Electromagnetic Fields;
 Neumann Problem;
 Polarization (Waves);
 Physics (General)