Bending hollow-core negative-curvature fiber for refractive index sensing based on surface plasmon resonance effect

We numerically investigated a novel refractive index (RI) sensor based on a liquid-filled and Au -coated hollow-core negative-curvature fiber (HC-NCF). In the design, the cladding area of the HC-NCF was composed of only one ring of six silica tubes, all the air holes in the fiber were filled with analytic liquids. The fiber bent in either the x or y-axis direction and Au-coated inside the single cladding tube in the corresponding bending direction. The influences of Au-coated HC-NCF structure parameters on the propagation characteristics under different bending directions were investigated using the finite element method (FEM). Moreover, the sensing performances in the RI range of 1.30-1.35 were evaluated through analyzing the position of the confinement loss peak. The simulation results showed that the HC-NCF RI sensor in the y-axis bending direction showed higher sensitivity, and the maximum sensitivity was 6.974 mu m/RIU. The sensor shows high sensitivity and provides an effective method for measuring the RI of liquids.