A novel D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance effect

In this paper, a novel D-shaped photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR) effect is proposed. By introducing a smiley-faced hole and Ag-TiO₂ composite micro-grating, the high RI sensing performances can be realized. With finite element method, the propagation characteristics of the proposed D-shaped SPR-PCF RI sensor are numerically investigated. The simulation results show that the average wavelength sensitivity (WS) is 5400 nm/RIU, and the maximum WS can reach 15,500 nm/RIU in the RI range from 1.30 to 1.39. Besides, the proposed D-shaped SPR-PCF RI sensor can obtain the maximum resolution (R) of 4.95 × 10⁻⁵RIU and the maximum figure of merit (FOM) of 423.78 RIU⁻¹, respectively. It is believed that the proposed SPR-PCF RI sensor has potential applications in the fields of environmental monitoring, biomedical analysis, and food safety management.