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 synth esis of binary profiles with several grooves in one period even for hi ghly 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 diffr active elements. In particular, it is shown that the inversion symmetr y of the diffraction pattern of a binary grating at normal incidence c an be efficiently broken by the use of non-symmetric binary wavelength -scale structures.