Design and research of a dual-parameter photonic crystal fiber sensor

We propose a dual-parameter photonic crystal fiber (PCF) sensor based on a surface plasmon resonance (SPR). It is used to detect a change in the refractive index (RI) and the temperature of the liquid. The contact area between the PCF and the liquid to be tested increases by polishing the PCF up and down. The large air holes that are on the upper and lower sides of the fiber core are plated with gold and silver film, respectively, to detect the RI of the external liquid. Moreover, polydimethylsiloxane (PDMS) is introduced into the large upper air hole to detect the temperature of the external liquid. Based on the finite element method, the diameter of the large air hole, the diameter of the ordinary air hole, the period, and the thickness of the metal layer are analyzed and discussed to find the most suitable parameter values to improve the sensor’s performance. The simulation results show that when the RI detection is in the range of 1.34–1.46, and the temperature detection is in the range of 20°C–30°C, the maximum RI sensitivity is 8400 nm/RIU and the maximum temperature sensitivity is 4.5 nm/°C. The proposed design is simple in structure and principle and solves the problem of multiparameter cross-sensitivity.