D-shaped photonic crystal fiber plasmonic refractive index sensor based on gold grating

In this work, we proposed a high resolution D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor based on gold grating. Gold grating is introduced to modulate the resonance wavelength and enhance the refractive index (RI) sensitivity. Structure parameters of PCF and gold grating are analyzed by finite element method (FEM) for optimizing the SPR sensor. The simulation results indicate that air hole pitch, air hole diameter and gold thickness and grating constant have little influence on the sensitivity of refractive index, which reduces the requirement of precise processing. For improving the resolution of RI sensing, two-feature (2F) interrogation method which combines wavelength interrogation and amplitude interrogation is used and the maximum theoretical resolution of SPR sensor reaches to 5.98*10-6 RIU in range of 1.36-1.38 and the wavelength sensitivity reaches to 3340nm/RIU. The proposed SPR sensor shows potential applications on developing a high-sensitivity, real time and fast-response SPR-RI sensor.