A High-Sensitivity Surface Plasmon Resonance Sensor Utilizing a Butterfly-Shaped Core for Ethanol Concentration Detection

In this study, we propose a highly responsive plasmonic refractive index (RI) biosensor based on a dual-core photonic crystal fiber (PCF). We employ the finite element method (FEM) to quantitatively assess the proposed design. The results obtained demonstrate that the amplitude interrogation strategy produces the maximum amplitude sensitivity for y-polarization, 605.82 RIU ⁻¹ . The method of wavelength interrogation for y-polarized modes showcases an impressive maximum sensitivity at wavelengths, measuring approximately 17000 nm per refractive index unit (RIU), alongside an exceptional wavelength resolution reaching 5.88× RIU. The recommended sensor has a figure of merit of about 298, and it is sensitive to changes in refractive index between 1.28 and 1.40. These promising results, coupled with its extensive sensing range, position the proposed biosensor as an outstanding option for detecting organic solutions, especially ethanol concentration.