Photonic crystal fiber refractive index sensor based on SPR

In this paper, a photonic crystal fiber sensor for surface plasmon resonance (SPR) is proposed and verified by wavelength interrogation. The structure design of the proposed PCF model is simple, and the size of the outer air hole has little effect on the sensor performance. Compared with the previously proposed sensor, the fabrication process of the sensor is very easy. At the same time, the surface plasmon resonance effect formed by the silver film on the polished surface provides a platform for the detection of liquid analytes. The numerical simulation results show that the trapezoidal photonic crystal fiber refractive index sensor based on silver-silicon cladding has an air hole d1 = 1.2 μm, an air hole d2 = 1.3 μm, an air hole spacing v = 1.5 μm, a metal silver film thickness t_Ag = 30 nm, the best sensing performance is achieved when the silicon oxide protective layer t_SiO2 = 20 nm. Its wavelength sensitivity is 24000 nm/RIU, the analyte refractive index detection range is 1.31–1.39, the resolution is 1.1102 × 10–6, and the amplitude sensitivity is − 4314.65RIU−1. Our proposed sensor uses SIO2 layer as a protective layer, which can not only prevent the plasma metal silver film from being oxidized, but also increase the sensitivity of the sensor. Therefore, the sensor designed in this study is very suitable for organic chemical detection and medical diagnosis.