Double-layered side-polished ultra-highly sensitive photonic crystal fiber-based surface plasmonic refractive index sensor

In this work, we offer a double-layered side-polished ultra-highly sensitive photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor for various biochemical analyte detection. Gold with titanium oxide (TiO2) as an adhesive layer has been employed acting as the plasmonic material. This study is fully based on simulation with finite element method for numerical inspection. Analyte channel along with a perfectly matched layer as the boundary condition has been placed at the outermost section of the sensor. After regulating different parameters, we attain a maximum wavelength and amplitude sensitivity of 138,800 nm/RIU and 2868 RIU−1, respectively, with a sensing range of 1.33–1.425 refractive indices of the analytes. Minimum wavelength resolution of 7.20 ×\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\times $$\end{document} 10–7 RIU is observed which ensures superior detection accuracy. In addition, the sensor achieves an ultra-high figure of merit (FOM) of 5783 RIU−1 which certifies an excellent detection limit. The FOM is the highest among all the previously reported PCF-SPR sensors to the best of the authors’ knowledge up to date. The sensor also reveals a very low average confinement loss of 2.40 dB/cm which assures practical feasibility by minimizing complexity associated with sensor length and splicing. A discontinuous plasmonic material layer has been used in the sensor which enhances cost-efficiency and sensitivity factor. On account of ultra-high sensitivity, low confinement loss, and excessive FOM, our proposed sensor can be very convenient and impressive in detecting various liquid biological and biochemical analytes.