Dispersion relation of guided-mode resonances and Bragg peaks in dielectric diffraction gratings - art. no. 036614

We present the dispersion relation of guided-mode resonances in non-dissipa tive dielectric diffraction gratings, both for s-polarized (TE mode) and p- polarized (TM mode) incident waves. We present a simple approximate theory as well as a rigorous calculation within the so-called coupled-wave theory. We discuss the dependence of the positions and the lifetimes of the resona nces on the thickness of the gratings and on the strength of its modulation . We find that the diffraction efficiency of the different orders show peak s at different Bragg orders.