Design and analysis of arc-shaped single core photonic crystal fiber sensor based on surface plasmon resonance

The selection of a suitable plasmonic material is crucial for achieving high-performance photonic crystal fiber-based surface plasmon resonance (PCF-SPR) sensors. However, most numerical investigations have been limited to PCF-SPR sensors with conventional circularly coated plasmonic metals due to their availability and rigid properties. In this work, a single-core arc-shaped PCF is designed and studied with sensing ingredients coated outside the fiber. The simulation and numerical analyses are performed using the full-vector finite element method to examine the effects of using gold as an active metal and also the deposition of Ta₂O₅ on gold. The results show that the arc-shaped sensor with gold film can obtain the maximum wavelength interrogation sensitivity (WIS) of 9500 nm/RIU within the refractive index (RI) range of 1.25–1.39 while the maximum amplitude interrogation sensitivity (AIS) reaches 579.26 RIU⁻¹ at 1.39 and resolution is 1.05 × 10⁻⁵. However, depositing Ta₂O₅ on the gold gives an improved maximum WIS and AIS of 22,000 nm/RIU and 1209.21 RIU⁻¹, respectively. With the coating of Ta₂O₅, the resolution improves to 4.55 × 10⁻⁶, making the proposed sensor design undoubtedly effective in detecting food chemicals such as butyl acetate and hydrocarbons along with different bio-analyte samples with a wide range of RI.