Abstract
A surface plasmon resonance (SPR) sensor based on dual-layered air hole shaped photonic crystal fiber (PCF) is proposed to realize the simultaneous measurement of refractive index (RI). The plasma materials silver (Ag) and titanium dioxide (TiO2) were sequentially coated on the outer surface of PCF to obtain enhanced sensing properties. By carefully adjusting the geometrical parameters, the simulation results show a maximum wavelength sensitivity of 72,000 nm/RIU for analyte refractive indices ranging from 1.26 to 1.365, which realizes the high-sensitivity sensing in the visible to near-infrared optical band. Moreover, the sensor attains a maximum figure of merit (FOM) of 229 and RI resolution of 1.29 × 10− 6. This work shows great potential for real-time, affordable, and accurate measurement in biomedical, biological and organic chemical domains.
Highlights
Over the past few years, surface plasmon resonance (SPR) sensing technology based on photonic crystal fibers (PCFs) has achieved notable applications in environmental monitoring, medical diagnostics, biochemical analysis, and food safety testing due to its outstanding performance and wide range of utilization (Cao et al 2018; Liu et al 2017b; Tong et al 2018)
When analyte is filled in air holes inside the PCF to form sensing channels, it is called internal sensing, while when the analyte directly contacts the outer surface of the PCF, this type of is referred to as external sensing
We propose a novel silver and TiO2 coated PCF-SPR sensor based on external sensing and operating at the visible to near-infrared optical band
Summary
Over the past few years, surface plasmon resonance (SPR) sensing technology based on photonic crystal fibers (PCFs) has achieved notable applications in environmental monitoring, medical diagnostics, biochemical analysis, and food safety testing due to its outstanding performance and wide range of utilization (Cao et al 2018; Liu et al 2017b; Tong et al 2018). Coating a high dielectric titanium dioxide (TiO2) film outside the metal layer can protect the silver from corrosion, and can significantly enhance the performance of the SPR sensor (Wang et al 2019; Zhou et al 2020). We propose a novel silver and TiO2 coated PCF-SPR sensor based on external sensing and operating at the visible to near-infrared optical band. Both theory and experiments demonstrated that the penetration depth of the evanescent field is deeper in the near-infrared band, which results in enhanced detection properties, and the appropriate laser source is accessible conveniently and affordably (Ziblat et al 2006). In order to obtain optimal performance, we carefully optimized numerous geometric parameters, such as fiber core diameter, pitch distance, analyte channel thickness and Ag/TiO2 coating thickness
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