Dual-core wide detection range D-shaped photonic crystal fiber dual parameters sensor based on surface plasmon resonance

Abstract

A dual-core D-shaped photonic crystal fiber sensor based on surface plasmon resonance is proposed for simultaneous detection of refractive index and temperature. The sensor features a fully symmetrical dual-core configuration with uniform air-hole diameters arranged in a hexagonal lattice, wherein two open-ring channels are incorporated on the D-shaped polished surface. One channel is coated with a gold (Au) film for RI sensing, while the other is filled with ‘polydimethylsiloxane (PDMS) + Au film’ mainly for temperature sensing, thereby effectively suppressing cross-sensitivity of the two sensing parameters. First, the finite element method (FEM) is employed to numerically optimize the structural parameters, within the optimized configuration, the proposed sensor can detect the RI and T simultaneously, with a range of 1.18–1.34 and − 40 °C to 100 °C, achieving a maximum RI sensitivity of 19,000 nm/RIU when RI is 1.34 and an average T sensitivity of − 0.5 nm/℃. Then, combining the sensitivity matrix decoupling method with the segmented fitting method, the detection accuracy of dual-parameter sensing has been effectively improved. Finally, a fabrication tolerance analysis confirms that a ± 10% variation in structural parameters exerts negligible influence on the resonance wavelength, demonstrating excellent robustness. Comparative analysis with previously reported dual-parameter sensors demonstrates that the proposed sensor provides competitive advantages in terms of wide low-RI detection range, broad temperature detecting range especially for low-temperature environment, and structural simplicity, making it highly promising for applications in gas sensing, chemical analysis, biomedicine, and low-temperature industrial monitoring.