Enhanced Diffraction by a Completely Planar Adjacent Grating

Abstract

Abstract A completely planar adjacent grating (AG) structure, which is composed of two identical planar dielectric gratings connected by thin metallic or dielectric film, is proposed in the paper. We carry out the numerical investigations of AG according to rigorous coupled-wave approach. The calculated results indicate that the completely planar grating structure is another highly efficient structure to enhance diffraction due to the interaction of surface waves excited by gratings at resonant conditions on both interfaces of the thin connection layer. The results also reveal that the modulation of refractive index is the same crucial role to excite or couple out surface wave as the roughness of the surface does.