▎ 摘　　要

A D-shaped photonic crystal fiber (PCF) with graphene-polymethyl methacrylate (PMMA) stack was employed to determine the refractive index from 1.33 to 1.41 and improve the extinction ratio. The proposed sensor was numerically analyzed using the finite element method. The polishing depth, period of the graphene-PMMA stack, and number of graphene layers on the sensing performance of the proposed structure were evaluated. The results indicate that the spectrum and sensitivity may be modulated. The proposed sensor exhibits a wavelength sensitivity of 2200 nm/RIU, a wavelength resolution of 4.54 x 10(-5) RIU, and linearity of 0.9918 with a high extinction ratio. Thus, this device has potential applications in PCF sensors.