Graphene enhanced dielectric-metal hybrid structure for high performance LSPR sensing

In this paper, we introduce what we believe to be a novel hybrid localized surface plasmonic resonance (LSPR) sensing structure that integrates silver nanodisks (Ag-disks), a zinc sulfide (ZnS) layer, and two-dimensional graphene material as a critical intermediary. By exciting the LSPR between the Ag-disks and the surface of the ZnS film, two sensing channels can be achieved in visible spectra. The sensing performance of the proposed sensor is experimentally investigated from two aspects: bulk refractive index and surface sensitivities. As a result, the bulk refractive index sensitivity of 271 nm/RIU is obtained, which is 56 percent higher than that of the sensor without the graphene nanosheets. Furthermore, in terms of surface sensitivity, the sensor with graphene also demonstrates a heightened response to the tiny change in the surface environment. The enhancement is attributed to the graphene-assisted near-field enhancement, which improves the excitation efficiency of LSPR. This work provides a theoretical basis feasible approach for the design of dual channel sensor and paves the way for the experimental exploration of LSPR sensing devices integrated with the 2D materials.