Exact solution to diffraction on a grating with parallelogramic grooves by the true modal method

摘要

The formalism of the True Modal Method up to now written for diffraction gratings with a rectangular profile is extended to 1D-periodic structures with parallelogramic grooves. An appropriate coordinate transformation is proposed in order to express analytically in a simple form the modes propagating in the grating region. Numerical examples of calculation of the propagation constants of the eigenmodes of the grating and of the total diffraction efficiency of lamellar parallelogramic structures are given and results are compared with those obtained by other methods.