Generating varying-period interference patterns of surface plasmons by diffraction gratings

Generation of surface plasmon interference patterns using a dielectric diffraction grating coated with a metal layer is studied. Modelling in the electromagnetic theory shows 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 tens times that of the incident wave. Techniques to control the interference pattern period by varying the wavelength and the incidence angle are discussed.