Enhanced Light Narrow Transmission through Cascaded Metallic Structure with Periodic Aperture Arrays

We present experimental and numerical studies on the enhanced light narrow transmission through cascaded Au/SiO_xN_y/Au aperture arrays by varying the refractive index and thickness of SiO_xN_y. It is found that the enhancement as well as narrowing of the optical transmission originates from the coupling role of surface plasmon polaritons. The results indicate that the transmission enhancement is highly dependent on the refractive index and thickness of SiO_xN_y. A higher transmission efficiency and narrower peak are obtained in Au/SiO_2.1N_0.3/Au structure with a small refractive index (1.6) and thin thickness (0.2 μm).