Dual-side polished SPR-PCF ultra-wide refractive index sensor with high amplitude sensitivity

Abstract A highly sensitive polished photonic crystal fiber sensor with an external sensing method has been proposed, which utilizes the surface plasmon resonance optical sensing technique. The two polished sides are coated with a plasmonic material called aluminum-doped zinc oxide that enhances the coupling strength and enables the SPR technology. The finite element method is employed to analyze the PCF numerically, which confirms a refractive index spanning from 1.18 to 1.45 for analyte detection. After analysis, the maximum value of amplitude sensitivity was found to be 6113.95 RIU-1, and the highest wavelength sensitivity of 20,500 nm/RIU was attained. Moreover, the maximum amplitude resolution of 1.46439×10-6 RIU and the highest wavelength resolution of 4.88×10-6 RIU were achieved from the designed PCF. The confinement loss was also fairly low, perfect for longer sensor lengths. The figure of merit resulted to be 820.924 RIU-1. This PCF sensor has been designed to be very stable during operation due to its high linearity in the visible and infrared spectrum. The proposed SPR-based PCF sensor has the merits of an extremely wide range of refractive index detection with high sensitivity and a significantly improved polished design, which can be used in various applications, including chemical analysis, gas detection, and biological cell detection with extremely high accuracy.