This paper presents a graphene-Au coated photonic crystal fiber (PCF) sensor in the visible regime. Designing a side-polish D-shaped plane over the PCF's defect of the periodic air holes can effectively enhance the evanescent field. Graphene on gold can enhance the sensor's sensitivity because it can stably adsorb biomolecules and increase the propagation constant of the surface plasmon polariton (SPP). Using the finite element method (FEM), we demonstrated that the sensing performance is greatly improved by optimizing the PCF's geometric structural parameter. The proposed PCF sensor exhibited high performance with a maximum wavelength sensitivity of 4200 nm/RIU, maximum amplitude sensitivity of 450 RIU-1, and refractive index resolution of 2.3 × 10-5 RIU in the sensing range 1.32-1.41. This research provides a potential application for the design a new generation of highly sensitive biosensors.
Keywords: graphene; optical fiber sensor; photonic crystal fiber; surface plasmon resonance.