Optical characteristics of surface plasmon resonance based on ZnO and metallic nanograting structures

We proposed the grating coupled surface plasmon resonance (GC-SPR) sensors using ZnO and metallic nanograting structures to enhance the sensitivity of an SPR sensor. The GC-SPR sensors were analyzed using the finitedifference time-domain method. The optimum resonance angles of 49 and 55.5 degrees are obtained in the 150 nm wide grating structure with a period of 300 nm for the ZnO thickness of 30 and 50 nm, respectively. Here, an enhanced evanescent field is obtained due to the surface plasmon on the edge of the bandgap when the ZnO and metallic grating structures are used to excite the surface plasmon.