High sensitivity and stability probe-type refractive index sensor based on an optical fiber metasurface

Abstract

A specific probe-type sensor based on an optical fiber metasurface was proposed and simulated for refractive index (RI) sensing. In this work, a metasurface has been integrated with an optical fiber platform, which has huge potential applications in imaging, sensing, and communications. The designed RI sensor consists of stacking layers of Au and ZnO in a 2D structure deposited on the end face of commercial multimode optical fiber. The parameters and performance of the sensor structure are designed and simulated. The results show that the designed sensor structure can generate mode resonance and realize RI sensing. Numerical simulations reveal that when the pair of Au/ZnO layers is 4, the width of the nanopillars is 300 nm, the thickness of the Au layer is 45 nm, the thickness of ZnO layer is 40 nm, and the RI sensitivity of the designed sensor reaches 1415 nm/RIU. In addition, the high RI of Au/ZnO, along with its compatibility with the fiber core (SiO2), makes it a perfect candidate to realize a multifunctional device. It also is a the biocompatible material that can be functionalized easily and used to realize biosensing.