Metal Nanowire Assisted Hollow Core Fiber Sensor for an Efficient Detection of Small Refractive Index Change of Measurand Liquid

Abstract

In this article, a cost-effective hollow core fiber (HCF)-based refractive index (RI) sensor using surface plasmon resonance (SPR) is designed and demonstrated. The sensor consists of a metal nanowire inside an HCF along with the sensing medium of various refractive indices. SPR effect between polaritons and the guided core mode of designed HCF is exploited to enhance the sensing performance. A full vectorial finite element method (FEM) is used for the design and analyses of the sensing probes which exhibit very high sensitivities of 12,400 nm/RIU, 10560 nm/RIU, and 6400 nm/RIU for copper (Cu), gold (Au), and silver (Ag), respectively with a resolution of 1.61 × 10−6 RIU. Additionally, the influence of metal wire dimension is also investigated in this paper. The reported simple and low-cost sensor exhibits high sensitivity for liquid with refractive indices slightly higher than that of the dielectric tube, such as olive oil, turpentine, kerosene, chloroform, carbon tetrachloride, glycerol, and toluene.