High sensitivity with wide detection range refractive index sensor based on dual-core photonic crystal fiber

This paper proposes a dual-core photonic crystal fiber (PCF) refractive index sensor. And we use the full vector finite element method (FEM) under the anisotropic perfect matching layer (PML) boundary condition to study the effects of various parameters of the sensor on performances. By two airholes which filled with the liquid to be analyzed, the two cores coupled with each other, the refractive index range is 1.36–1.44. Numerical calculations were carried out on the sensor characteristics. The simulation results show that: when the refractive index range is 1.36–1.42, the average sensitivity can be up to 10,315 nm/RIU (refractive index unit), the highest sensitivity can be up to 13,502 nm/RIU when the liquid refractive index is 1.42, the quadratic fitting coefficient R12\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${R}_{1}^{2}$$\end{document} = 0.99969. And when the refractive index range is 1.42–1.44, the average sensitivity can be up to 17,980 nm/RIU, the highest sensitivity can be up to 22,380 nm/RIU when the liquid refractive index is 1.44, the quadratic fitting coefficient R22\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${R}_{2}^{2}$$\end{document} = 0.99999. The sensor we proposed is suitable for biomolecules and chemistry, as its conventional wide detection range with high sensitivity. Most importantly, a new idea of broadening the detection range is put forward for reference.