Design and numerical analysis of a fractal cladding PCF-based plasmonic sensor for refractive index, temperature, and magnetic field

This paper presents a new fractal cladding PCF-based plasmonic sensor for refractive index (RI), temperature, and magnetic field using a single-polarization, single-peak scanning technique. A layer of gold (Au) is sputtered on the outer circular surface of the PCF for direct RI sensing. One-half of the outermost air holes are filled with a temperature-sensitive fluid, and the other half with a magnetic-field-sensitive liquid. An in-depth analysis and numerical examination of the coupling behavior and sensing features are presented by the finite element method (FEM). In the infrared wavelength interval from 1.40 µm to 1.80 µm, the RI sensing benchmarks in the 1.40–1.46 range indicate a maximum wavelength sensitivity of 3000 nm/RIU and a maximum amplitude sensitivity of 362.67 /RIU. The wavelength resolution associated with RI is 3.33 × 10⁻⁵ RIU. The benchmarks for temperature sensing show maximum values of amplitude sensitivity, wavelength sensitivity, and resolution of 24.46/°C, − 1.2 nm/°C, and 8.33 × 10–2/°C respectively, from 0 °C to 75 °C. Finally, the magnetic field sensing benchmarks show 103.52/Oe, 0.67 nm/Oe, and 1.0 × 10^-4 Oe as maximum values for amplitude sensitivity, wavelength sensitivity, and resolution, respectively, in the range of 5–200 Oe. The proposed fractal cladding PCF-based plasmonic sensor can potentially be deployed as a lab-on-a-PCF for a variety of applications, including hyperthermia monitoring, medical and chemical sample analysis, biomolecular engineering, climatology, magnetocardiography, and magnetomyography.