Research on Characteristics of Wedge-Shaped Open-Cavity Mach-Zehnder Sensing Structure for Seawater Temperature

• Published in: IEEE transactions on instrumentation and measurement 2021, Vol.70, p.1-7
• Main Authors: Lin, Zi-Ting, Zhao, Yong, Lv, Ri-Qing, Zheng, Hong-Kun, Wang, Xi-Xin
• Format: Article
• Language: English
• Subjects: High sensitivity; Loss measurement; low cost; low loss; Mach–Zehnder interferometer (MZI); Ocean temperature; Optical fiber sensors; Optical fibers; Optical variables measurement; Seawater; Sensitivity; Splicing; Temperature; Temperature measurement
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2021.3088429

For the purpose of monitoring seawater temperature, a novel Mach-Zehnder (MZ) temperature-sensing structure with a wedge-shaped open cavity is presented and experimentally studied in this article. The open-cavity structure realizes the direct contact between the sensing optical path and the external environment, and ensures the high sensitivity of the structure. At the same time, it achieves not only low loss by direct fusion splicing instead of dislocation fusion splicing, but also low cost by hydrofluoric (HF) etching instead of femtosecond processing. In addition, the temperature sensitivity of the sensor structure proposed in this article can reach 1.5 nm/°C without temperature-sensitive material filled, and 6 nm/°C with silicone oil filled. Moreover, the resolution of the sensing structure is 0.24 °C based on the criterion of 3\sigma .