Application de l'étude de la diffraction par un réseau à la propagation dans les guides périodiques

The propagation of electromagnetic waves in periodic waveguides is investigated analytically using the method described by Chandezon et al. (1980) for diffraction gratings. The Maxwell equations are solved in covariant tensor form with nonorthogonal coordinates adapted to the problem geometry, leading to a matrix characteristic of the coordinates and the medium for which eigenvalues and eigenvectors must be found. The dispersion condition of a rectangular meander waveguide can then be calculated, since the linear system becomes homogeneous in this case. Waveguides with glide-reflection symmetry are shown to reduce the order of the system by half. Numerical results are presented graphically, and the application of the same techniques to multilayer gratings is suggested.