Surface plasmon resonance sensor based on U-shaped photonic quasi-crystal fiber.

A high-sensitivity surface plasmon resonance (SPR) sensor is designed and analyzed numerically. The sensor is constructed on the eightfold U-shaped photonic quasi-crystal fiber (PQF) and coated with indium tin oxide (ITO). The coupling between the core mode and surface plasmon polariton mode is enhanced due to shortening of the distance between the core and the ITO layer, so that the PQF-SPR sensor exhibits high refractive index (RI) sensitivity in the near-infrared region. The maximum wavelength sensitivity and the corresponding resolution of this sensor are 42,000 nm/RIU and 2.38×10-6RIU, respectively. The average wavelength sensitivity is 12,750 nm/RIU in the refractive index range of 1.306-1.386. This advanced sensor is suitable for the determination of RIs in the near-infrared region.

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 1.034×10-6RIU 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.

Surface plasmon resonance sensor based on eccentric core photonic quasi-crystal fiber with indium tin oxide.

A sensing device composed of an eccentric core photonic quasi-crystal fiber based on surface plasmon resonance is designed using indium tin oxide (ITO) as the sensitive materials. The ITO film is deposited on the outside surface of the fiber to excite plasmonic interactions and facilitate refractive index (RI) detection. This eccentric core structure makes the evanescent field coupled effectively with analyte to achieve higher sensitivity. The influence of RI and structural parameters of different analytes on sensor performance was calculated by the finite-element method. In the analyte RI range between 1.33 and 1.39, the wavelength sensitivity reaches 21,100 nm/RIU, and the average sensitivity of 8750 nm/RIU is achieved at a resolution of 4.739×10-6 RIU. The sensor has large potential in the detection of unknown RI analytes in the near-infrared region.