Refractive index sensing characteristics in a D-shaped photonic quasi-crystal fiber sensor based on surface plasmon resonance

High FOM PCF-SPR refractive index sensor based on MgF2-Au double-layer films

A simple twin-core D-shape photonic crystal fiber sensor based on surface plasmon resonance (SPR) is designed for the measurement of refractive indices (RI). The twin-core D-shape structure enhances the SPR effect, and the M g F 2-Au dual-layer film narrows the linewidth in the loss spectrum, consequently improving both the sensitivity and figure of merit (FOM). The properties of the sensor are analyzed by the finite element method. In the RI range of 1.32-1.42, the maximum wavelength sensitivity, FOM, and resolution are 62,000 nm/RIU, 1281R I U -1, and 1.61×10-6, respectively.

Surface plasmon resonance sensor composed of a D-type photonic crystal fiber with a three-layer coating

A surface plasmon resonance sensor composed of photonic crystal fibers (PCF-SPR) with an A u-T i O 2-A u triple layer is designed for refractive index (RI) sensing and analyzed theoretically by the finite element method. The sensor exhibits enhanced resonance coupling between the core mode and surface plasmon polariton (SPP) mode as well as better sensitivity than the structure with a single gold coating. Furthermore, the A u-T i O 2-A u tri-layer structure narrows the linewidth of the loss spectrum and improves the figure of merit (FOM). In the analyte RI range of 1.30-1.42, the maximum wavelength sensitivity is 20,300 nm/RIU, resolution is 4.93×10-6, amplitude sensitivity is 6427R I U -1, and FOM is 559R I U -1. The results provide insights into the design of high-performance PCF-SPR sensors.

D-shaped photonic crystal fiber sensor based on the surface plasmon resonance effect for refractive index detection

In this paper, a photonic crystal fiber (PCF) sensor based on the surface plasmon resonance (SPR) effect for refractive index (RI) detection is proposed. We design a D-shaped polished PCF structure consisting of air holes arranged in a hexagonal lattice. The silver film is coated on the middle channel of the polished surface of the PCF. The finite element method is used to analyze the propagation characteristics of the proposed D-shaped SPR-PCF sensor. Simulation results show that the proposed D-shaped SPR-PCF sensor has a maximum wavelength sensitivity of 30,000 nm/RIU, an average wavelength sensitivity of 6785.71 nm/RIU, and a maximum resolution of 3.33×10-6 R I U in the RI range of 1.22-1.36. Owing to the high wavelength sensitivity in the considered RI range, the proposed D-shaped SPR-PCF sensor is suitable for applications in water contamination detection, liquid concentration measurement, food safety monitoring, etc.

Short dual-core GaAs photonic crystal fiber splitter with a broad bandwidth and ultrahigh extinction ratio

Microstructured polarization beam splitters (PBSs) have attracted much interest in recent years. Here, a ring double-core photonic crystal fiber (PCB) PSB (PCB-PSB) with an ultrashort, broadband, and high extinction ratio (ER) was designed. The effects of the structural parameters on the properties were analyzed by the finite element method, which revealed that the optimal length of the PSB was 19.08877 µm and the ER was -324.257d B. The operating bandwidth for an ER of less than -20d B is 440 nm, and the wavelength range spans the full E+S+C+L+U band between 1,320 and 1,760 nm. The fault and manufacturing tolerance of the PBS was demonstrated for structural errors of ±1%. Moreover, the influence of temperature on the performance of the PBS was determined and discussed. Our results show that a PBS has excellent potential in optical fiber sensing and optical fiber communications.

HE1,1 mode excited surface plasmon resonance for high-sensitivity sensing by photonic crystal fibers

Surface plasmon resonance (SPR) is widely used in photonic crystal fiber sensors. In this work, a photonic crystal fiber sensor based on HE_1,1 mode excited SPR is designed and analyzed by the finite element method. The maximum wavelength sensitivity, optimal resolution, and amplitude sensitivity of the optical fiber sensor are 24,600 nm/RIU, 4.07×10^-6RIU, and 1164.13RIU^-1, respectively, for the refractive index range between 1.29 and 1.39. The sensor has excellent properties and wide application prospects in bimolecular and biochemical sensing, environmental monitoring, food safety, and other fields.

Highly sensitive dual-core photonic quasicrystal fiber methane sensor based on surface plasmon resonance

A highly sensitive dual-core photonic quasicrystal fiber methane sensor based on surface plasmon resonance is designed and analyzed. In this sensor, cryptophane E is doped with polysiloxane and Ag and used as the sensitive film and plasma medium, respectively, for sensitive detection of methane. The influence of the structural parameters on the sensor properties is analyzed by the finite element method. The optimized dual-quasi-D-shape structure has excellent methane-sensing properties such as maximum and average wavelength sensitivities of 14 and 10.98 nm/%, respectively, in the methane concentration range of 0%-3.5%. The sensitivity is better than that of similar sensors reported previously.

Bragg grating sensor for refractive index based on a D-shaped circular photonic crystal fiber

In this paper, a silica-based D-shaped circular photonic crystal fiber Bragg grating sensor for refractive index sensing is proposed theoretically. D-shaped fiber construction can effectively enhance the coupling effect between the guiding mode and external liquid analyte, which then causes a distinct shift in the typical reflection spectrum as the refractive index of the analyte varies. This design exhibits highly improved sensitivity of 487 nm/RIU in a large refractive index range from 1.30 to 1.40 compared with the previous fiber grating sensors. Study of the dependence of sensing performance on the structure parameters suggests that the resonance peak shifts towards longer wavelengths with the increased air-hole diameter of fiber, while it is almost immobile as the hole spacing and the number of air-hole layers change in a certain range. For the influence of the Bragg grating structure, results show that the resonance peak is not sensitive to the grating length, but linearly increases as the grating period expands. The effects of polishing depth and fiber preparation error on the sensor are also discussed in detail. This high-sensitivity sensor based on a D-shaped photonic crystal fiber and Bragg grating has great potential in biochemical detection, environmental monitoring, and medical sensing.

High-sensitivity methane sensor composed of photonic quasi-crystal fiber based on surface plasmon resonance

A photonic quasi-crystal fiber (PQF) methane sensor based on surface plasmon resonance (SPR) is designed and described. The double-side polished six-fold photonic quasi-crystal fiber coated with a silver film produces enhanced SPR effects and sensitivity. A nanostructured thin film with cryptophane-E-doped polysiloxane is deposited on silver as the methane-sensitive surface layer and to mitigate oxidation of silver. The sensor is analyzed and optimized numerically by the full-vector finite element method. For methane concentrations in the range of 0% to 3.5%, the maximum sensitivity of the sensor is 8 nm/%, and the average sensitivity is 6.643 nm/%. Compared to traditional gas sensors, this sensor provides accurate sensing of methane besides offering advantages such as the low cost, miniaturized size, online monitoring, and immunity to electromagnetic field interference.

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.

Side-coupled liquid sensor and its array with magneto-optical photonic crystal

In this paper, a side-coupled liquid sensor and its array based on magneto-optical photonic crystal are proposed. The sensitivity and quality factor of a single magneto-optical photonic crystal sensor are 0.492 mm/RIU and 181,760, respectively. After arraying, the sensitivity of the single microcavity sensor can reach from 0.1 to 0.35 mm/RIU, and the corresponding quality factor can reach from 5×10⁴ to 7×10⁴. Moreover, the structure has good robustness. This work will provide reference for the design of high-performance photonic crystal microcavity sensor arrays.