Sensitivity and linearity enhanced wide-detection range surface-plasmon-resonance photonic-crystal-fiber sensor

A refractive-index (RI) sensor based on photonic crystal fiber (PCF) and surface plasmon resonance (SPR) is proposed and demonstrated in this paper. The influences induced by the changes of the diameter of gold nanowire, air-hole spacing, diameter of central hole and diameter of the air hole on both sides of central hole are investigated to analyze and optimize the performances of the SPR-PCF sensor. It is indicated that the proposed sensor is suitable for the detection of the RI of material in the range from 1.15 to 1.45. Moreover, the optimized RI sensitivity can reach -5893.9 nm/RIU and the optimized R-2 can be larger than 0.999. Detections of the alcohol with different concentrations are carried out to demonstrate the performance of the SPR-PCF. The sensitivities in both polarization directions are -192 nm/% and -198 nm/% when the concentration is changed from 10% to 87%. Moreover, the sensitivities for RI-detection are -5900 nm/RIU and -6116 nm/RIU with the corresponding R-2 larger than 0.9993 in both polarization-directions. Our detailed results will help to understand the SPR phenomenon in hexagonal PCF, and promote the realization and application of SPR-PCF sensors.

Automated summary

This study introduces and demonstrates a novel refractive-index sensor based on photonic crystal fiber and surface plasmon resonance, suitable for detecting the refractive index of materials ranging from 1.15 to 1.45 with optimized RI sensitivity and R-2 values. Experimental results show high sensitivity and stability in detecting alcohol with different concentrations, indicating the potential of the sensor for practical applications.