Analysis of experimental reflection spectra from diffraction gratings using the Rayleigh theory and a rigorous method

We obtain the reflection spectra of p-polarized light from metallic gratings fabricated by means of the interference technique. The gratings have constant period and heights are varied by changing the exposure time of the interference pattern on the sample. The experimental spectra show two minima due to the excitation of surface plasmons, and they are compared with the corresponding numerical results obtained with two models, the Rayleigh theory and the rigorous integral method. In order to demonstrate the validity of the Rayleigh hypothesis the amplitudes of the gratings are chosen close to the Rayleigh limit.