Differential Theory of Diffraction by 2D-Periodic Objects

摘要

The latest state-of-the-art of the differential theory of diffraction by periodic objects is presented for the case of 2D (crossed) gratings made of isotropic or anisotropic material. It includes both the S-matrix propagation algorithm and the fast Fourier factorisation. In the particular case of lamellar grating profiles, the method reduces to the RCW theory. Although the RCW theory could be extended to any groove shape, constituting an efficient method in TE polarization, it gives poorly converging results in TM polarization.