Plasmonic Sensor for Detecting High Refractive Index with Analyte-Infused Photonic Crystal Fiber

This article introduces an innovative sensor leveraging surface plasmon resonance constructed within the framework of photonic crystal fiber (PCF) for measuring refractive indices. This innovative sensor strategically places liquid analyte within a central, larger air hole of the PCF, while housing the plasmonic medium in a separate air hole, effectively mitigating potential oxidation issues arising from aqueous environments. Three distinct configurations, denoted as Model A, Model B, and Model C, for employing the plasmonic medium in PCF are introduced. Model A utilizes gold nanowire in one air hole, Model B employs thin film coatings in one air hole, and Model C features thin film coatings in double air holes around the core. Numerical investigations of these sensor designs are conducted using finite element methods, and their performance is assessed through wavelength and amplitude integration techniques. These diverse configurations offer varying refractive index detection ranges of 1.42-1.48, 1.44-1.52, and 1.45-1.53, each exhibiting impressive maximum wavelength sensitivities of 17,000, 16,000, and 15,000 nm/RIU, respectively. Furthermore, the maximum amplitude sensitivities are measured at 647, 1551, and 1542 RIU
^-1
. Notably, the nanowire-based sensor displays superior linearity among these schemes. With detection ranges surpassing that of silica, these sensors are poised for diverse applications across fields such as chemistry, biology, and medical diagnostics.