High-Sensitivity Detection of Hazardous Chemical by Special Featured Grating-Assisted Surface Plasmon Resonance Sensor Based on Bimetallic Layer

In this article, we present the analysis of a special featured grating-assisted surface plasmon resonance (SPR) phenomena by multiple stacked metamaterial and silver layers as one grating structure. The bimetallic layer of gold (Au) and silver (Ag) has been used with stacked multiple negative refractive index (NRI) metamaterial layers to explore the special featured sensing capability. NRI grating with Ag layer supports better coupling to excite the multimode for the proposed structure at the same excitation condition. Hence, the alternating layer of NRI material along with Ag is used as a grating structure that is an excellent combination of the grating layer through which the proposed structure supports better coupling to the adjacent sensing region. The grating parameters have been optimized in such a way to enhance the number of resonance modes in the sensing region. It is found that SPR sensor sensitivity using negative diffraction order has a larger dip, while the resonant angle became wider for positive diffraction order. The transfer matrix method is used for the calculation of various parameters. The special featured structure with corresponding response graphs is described along with discussing what happens when the metamaterial layer thickness varies (and vice versa). Sensitivity tunability is demonstrated with variable metamaterial layer thickness. A sensitivity study is a significant parameter in the design of any high-sensitive sensor to enhance the performance. Hence, the sensitivity slope property has been explored further for each case.