Diffraction gratings for generating varying-period interference patterns of surface plasmons

The generation of surface plasmon interference patterns using a dielectric diffraction grating with a metal film applied in the substrate region is studied. It is shown by way of numerical simulation within the rigorous electromagnetic theory that high contrast interference patterns with a period several times smaller than that of the diffraction grating can be produced. At the interference maxima, the field intensity is ten times that of the incident wave. Techniques to control the interference pattern period by varying the wavelength and the incidence angle are discussed.