Design and simulation of a fiber sensing system for metal ion detection based on side-polished fiber and a coated fiber grating

Subject of study. A fluid metal ion detection device is designed to solve the issue of heavy metal water quality detection in real life, which is used by a fusion of a side-throwfiber-assisted fluid structure and a long-period fiber grating coated with a metal chelator film. The aim of the work is to design a fiber-optic fluid system for the simultaneous qualitative and quantitative analysis of metal ions in a liquid. Method. The refractive index bands of common contaminated water sources are selected for the numerical simulation of metal ion species and concentration sensing characteristics. Main results. The results show that the interference wavelength is red-shifted with the increase of the filled fluid concentration. Its refractive index sensing sensitivity is calculated to be about 3343.33 nm/RIU. Meanwhile, when the refractive index of the long-period fiber grating film layer increases from 1.2 to 1.44, the loss peak decreases by a total of 6.011 dB, and thus the ion species can be identified. Practical significance. Therefore, this sensing system offers the possibility of real-time detection of fluid ion orientation. (c) 2024 Optica Publishing Group