The visibility of Moire fringes is a major feature for their application in optical metrology. With the help of surface plasmon polariton (SPP) waves excited for a metal layer whose permittivity match with that of its dielectric partner, the visibility of Moire fringes is improved. For a dielectric-metal-dielectric sandwich structure between two subwavelength gratings with the optimum thicknesses of the layers but not appropriately matched permittivity, we found that it is easy to achieve a remarkable enhancement (visibility up to 0.88) of the Moire fringes facilitated by the excitation of SPP waves. (c) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
