High-sensitivity SPR sensor based on the eightfold eccentric core PQF with locally coated indium tin oxide

A highly sensitive surface plasmon resonance (SPR) sensor comprising an eccentric core photonic quasi-crystal fiber (PQF) coated with indium tin oxide is designed and numerically analyzed. The novel, to the best of our knowledge, structure with an eccentric core layout and local coating not only strengthens coupling between the core mode and surface plasmon polariton mode but also provides higher refractive index sensitivity in the near-infrared region. Analysis based on the finite element method to assess the performance of the sensor and optimize the structural parameters reveals that the maximum wavelength sensitivity and resolution are 96667 nm/RIU and 1.034 × 10⁻⁶ RIU in the sensing range between 1.380 and 1.413, respectively. Meanwhile, the average sensitivity is enhanced to 25458 nm/RIU. The sensor is expected to have broad applications in environmental monitoring, biochemical sensing, food safety testing, and related applications due to the ultrahigh sensitivity and resolution.