Resonance effects for the diffraction by high reflecting gratings in the double resonances case

The authors present results which show a high efficiency for the modified perturbation method in the analysis of the resonance diffraction. In spite of the simplicity, they are in a very good agreement with existing experimental data. Moreover, the simplicity enables one to find the cases of special interest both for further experimental investigations and for solving the problem of high-accuracy measurements of gratings and media parameters, and for designing unique optical devices.