▎ 摘　　要

A D-shaped photonic crystal fiber (PCF)-based plasmonic sensor is proposed for detecting refractive index (RI) variations within the range of 1.33-1.38. The center hollow core has formed using Bezier curves, which confines light within the core by the principle of photonic band gaps. An analyte is injected into a core to adjust its refractive index. Light propagating in the air core is affected by the analyte filled in the core, causing plasmon waves to be produced on the metal surface. On top of this structure, a chemically stable gold (Au) metal layer is placed as a plasmonic material. Numerical studies are carried out using the finite element method (FEM). The gold layer thickness is optimized and obtained an average sensitivity of 5600 nm/RIU. The sensor's sensitivity is enhanced by sandwiching graphene between an analyte and a gold film. The average sensitivity of the sensor increases by 2000 nm/RIU after graphene is incorporated, having reached 7600 nm/RIU according to the results obtained. The sensor can efficiently detect slight variations in the analyte indices and, thus, it is used in various chemical and biosensing applications.