Abstract

A novel π-phase-shifted (PS) long-period fiber-grating (LPFG) sensor operating near the phase-matching turning point (PMTP) was proposed. The PS-LPFG sensor can simultaneously detect temperature, strain, refractive index (RI), and pH. Due to the introduction of π phase shift, the double resonance peak of the selected cladding mode was divided into four loss peaks, which is convenient for multiparameter measurement. By monitoring the resonant-wavelength shifts of four dips of PS-LPFG, simultaneous detection of temperature, strain, RI, and pH can be achieved. Moreover, using a simple LPFG design on one fiber and a multiparameter matrix algorithm, the crosstalk between multiple signals was eliminated. Graphene oxide/polyvinyl alcohol (GO/PVA) hydrogel was coated onto the grating sensing area to measure the change in pH, and the sensitivity was higher than that of the same type of fiber-grating sensor. Results showed that the maximum sensitivity of temperature, strain, RI, and pH of the fabricated phase-shifted grating sensing structure were 0.2128 nm/°C, 0.1225 nm/με, 718 nm/RIU, and -1.0166 nm/pH, respectively. Overall, the proposed sensor had great potential applications in monitoring marine environments and biochemistry sensing.

Reflective long-period fiber grating-based sensor with Sagnac fiber loop mirror for simultaneous measurement of refractive index and temperature

Jianying Yuan, Chun-Liu Zhao, Yumeng Zhou, Xiangdong Yu, Juan Kang, Jianfeng Wang, and Shangzhong Jin
Appl. Opt. 53(29) H85-H90 (2014)

Smart design of a long-period fiber grating refractive index sensor based on dual-peak resonance near the phase-matching turning point

Qiang Ling, Zhengtian Gu, and Kan Gao
Appl. Opt. 57(10) 2693-2697 (2018)

Strain, bending, refractive index independent temperature sensor based on a graded index multimode fiber embedded long period fiber grating

Huiwen Niu, Wenhuan Chen, Yue Liu, Xiren Jin, Xiang Li, Feng Peng, Tao Geng, Shuo Zhang, and Weimin Sun
Opt. Express 29(15) 22922-22930 (2021)

Simultaneous measurement of the surrounding refractive index and temperature using a local-micro-structured long-period fiber grating sensor operating near the phase-matching turning point

Ying Wang, Zhengyuan Li, Bo Pang, Xinyu Wang, Yihao He, Jinghong Zhang, Leaven Romeo Mupfukirei, Kai Zhang, Qiang Ling, Zhangwei Yu, and Daru Chen
J. Opt. Soc. Am. B 41(4) 915-920 (2024)

Phase-shift formed in a long period fiber grating and its application to the measurements of temperature and refractive index

Keisuke Hishiki and Hongpu Li
Opt. Express 21(10) 11901-11912 (2013)