Quantitative theoretical study of the plasmon anomalies of diffraction gratings

Using some simple considerations based on the Fresnel formula, the existence of strong absorptions of visible radiation by diffraction gratings is demonstrated. The theory is verified by comparison with numerical results from the previous integral formalism computer programs. Finally, a very simple formula which predicts in a qualitative and quantitative manner the absorption of energy is derived. This theory, which can be applied to other anomalies, leads to the discovery of a surprising phenomenon: in the visible region and with the usual metallic gratings, it is possible to totally absorb an incident monochromatic wave.