Rigorous modal theory for multiply grooved lamellar gratings

An extension of the rigorous modal theory for dielectric and finitely conducting gratings is presented, which permits the analysis and synthesis of binary profiles with several grooves in one period even for highly conducting gratings in TM polarization. We apply the modal method to the analysis of the effects of finite conductivity in diffractive optics, and to the synthesis of reflection-mode resonance-domain diffractive elements. In particular, it is shown that the inversion symmetry of the diffraction pattern of a binary grating at normal incidence can be efficiently broken by the use of non-symmetric binary wavelength-scale structures. © 1994.