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Zhou J, Sun Y, Liu H, Li H, Wang Y, Jiang J, Xu D, Yao J. The Highly Sensitive Refractive Index Sensing of Seawater Based on a Large Lateral Offset Mach-Zehnder Interferometer. SENSORS (BASEL, SWITZERLAND) 2024; 24:3887. [PMID: 38931671 PMCID: PMC11207972 DOI: 10.3390/s24123887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/24/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024]
Abstract
A novel fiber sensor for the refractive index sensing of seawater based on a Mach-Zehnder interferometer has been demonstrated. The sensor consisted of a single-mode fiber (SMF)-no-core fiber (NCF)-single-mode fiber structure (shortened to an SNS structure) with a large lateral offset spliced between the two sections of a multimode fiber (MMF). Optimization studies of the multimode fiber length, offset SNS length, and vertical axial offset distance were performed to improve the coupling efficiency of interference light and achieve the best extinction ratio. In the experiment, a large lateral offset sensor was prepared to detect the refractive index of various ratios of saltwater, which were used to simulate seawater environments. The sensor's sensitivity was up to -13,703.63 nm/RIU and -13,160 nm/RIU in the refractive index range of 1.3370 to 1.3410 based on the shift of the interference spectrum. Moreover, the sensor showed a good linear response and high stability, with an RSD of only 0.0089% for the trough of the interference in air over 1 h.
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Affiliation(s)
- Jingwen Zhou
- School of Marine Science and Technology, Tianjin University, Tianjin 300072, China;
| | - Yue Sun
- School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (Y.S.); (H.L.); (H.L.); (J.J.); (J.Y.)
| | - Haodong Liu
- School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (Y.S.); (H.L.); (H.L.); (J.J.); (J.Y.)
| | - Haibin Li
- School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (Y.S.); (H.L.); (H.L.); (J.J.); (J.Y.)
| | - Yuye Wang
- School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (Y.S.); (H.L.); (H.L.); (J.J.); (J.Y.)
| | - Junfeng Jiang
- School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (Y.S.); (H.L.); (H.L.); (J.J.); (J.Y.)
| | - Degang Xu
- School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (Y.S.); (H.L.); (H.L.); (J.J.); (J.Y.)
| | - Jianquan Yao
- School of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (Y.S.); (H.L.); (H.L.); (J.J.); (J.Y.)
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Du C, Zhao S, Wang Q, Jia B, Zhao M, Zhang L, Cui L, Chen S, Deng X. A Seawater Salinity Sensor Based on Optimized Long Period Fiber Grating in the Dispersion Turning Point. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23094435. [PMID: 37177639 PMCID: PMC10181512 DOI: 10.3390/s23094435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/28/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023]
Abstract
Variations of seawater salinity often cause ocean internal waves, water masses and stratification, which affect the stability of the ocean environment. Therefore, the study of seawater salinity is significant for the prediction of changes in the ocean environment. However, existing methods for measuring seawater salinity generally have the disadvantages of low sensitivity and low accuracy. In this work, we proposed a seawater salinity sensor based on long period fiber grating (LPFG) in the dispersion turning point (DTP), which has demonstrated the possibility to fabricate LPFG with a shorter grating period by CO2 laser in a thin single mode fiber (SMF) of 80 μm cladding diameter without etching. For obtaining higher sensitivity that could meet the measurement requirement in practice, the proposed sensor was optimized by combining etching cladding and DTP. After the LPFG working near DTP was fabricated by a CO2 laser, the cladding diameter was reduced to 57.14 μm for making cladding mode LP1,7 work near DTP by hydrofluoric acid (HF) solutions. The experimental results have demonstrated that a sensitivity of 0.571 nm/‱ can be achieved when the salinity increases from 5.001‱ to 39.996‱, and the sensor shows good repeatability and stability. Based on its excellent performance, the optimized LPFG is a prospective sensor to monitor seawater salinity in real time. Meanwhile, a low-cost way was provided to make LPFG work near DTP instead of ultraviolet exposure and femtosecond laser writing.
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Affiliation(s)
- Chao Du
- College of Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Shuang Zhao
- College of Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Qiuyu Wang
- College of Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Bin Jia
- College of Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Mingzhe Zhao
- College of Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Li Zhang
- College of Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Liqin Cui
- College of Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
- College of Physics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Shizhe Chen
- Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao 266001, China
| | - Xiao Deng
- College of Physics, Taiyuan University of Technology, Taiyuan 030024, China
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Li G, Wang Y, Shi A, Liu Y, Li F. Review of Seawater Fiber Optic Salinity Sensors Based on the Refractive Index Detection Principle. SENSORS (BASEL, SWITZERLAND) 2023; 23:2187. [PMID: 36850782 PMCID: PMC9965139 DOI: 10.3390/s23042187] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/21/2023] [Accepted: 02/11/2023] [Indexed: 06/18/2023]
Abstract
This paper presents a systematic review of the research available on salinity optic fiber sensors (OFSs) for seawater based on the refractive index (RI) measurement principle for the actual measurement demand of seawater salinity in marine environmental monitoring, the definition of seawater salinity and the correspondence between the seawater RI and salinity. To further investigate the progress of in situ measurements of absolute salinity by OFSs, the sensing mechanisms, research progress and measurement performance indices of various existing fiber optic salinity sensors are summarized. According to the Thermodynamic Equation of Seawater-2010 (TEOS-10), absolute salinity is recommended for sensor calibration and measurement. Comprehensive domestic and international research progress shows that fiber-optic RI sensors are ideal for real-time, in situ measurement of the absolute salinity of seawater and have excellent potential for application in long-term in situ measurements in the deep ocean. Finally, based on marine environmental monitoring applications, a development plan and the technical requirements of salinity OFSs are proposed to provide references for researchers engaged in related industries.
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Affiliation(s)
- Gaochao Li
- State Key Laboratory of Transducer Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongjie Wang
- State Key Laboratory of Transducer Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ancun Shi
- State Key Laboratory of Transducer Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Yuanhui Liu
- State Key Laboratory of Transducer Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Fang Li
- State Key Laboratory of Transducer Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
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Yu Q, Li X, Zhou X, Gao X, Lv R, Nguyen LV, Warren-Smith SC, Zhao Y. Temperature compensated fiber optic magnetic sensor based on the combination interference principle. OPTICS LETTERS 2022; 47:2558-2561. [PMID: 35561400 DOI: 10.1364/ol.456552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 04/21/2022] [Indexed: 06/15/2023]
Abstract
In this paper, a highly sensitive temperature compensated fiber optic magnetic field sensor by Sagnac and Mach-Zehnder combination interference (SMZI) is proposed and verified. The sensing structure relies on microstructured exposed core fiber (ECF) filled with ethanol and magnetic fluid (MF). The refractive index of MF and ethanol is affected by the magnetic field and temperature (MFT). SMZI is based on the multimode and birefringence characteristics of ECF. The measurement principle is that the spectra of Sagnac interference and Mach-Zehnder interference have respective sensitivities to the MFT. The magnetic sensitivity can reach 1.17 nm/mT, and the temperature sensitivity is up to -1.93 nm/°C. At the same time, the sensor has good repeatability and low detection limits of 0.41 mT and 0.25°C, respectively. It not only solves the cross-influence of temperature but also makes the spectral analysis more intuitive. The sensor has a broad development prospect in the application of MFT detection.
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Lin Z, Lv R, Zhao Y, Zheng H, Wang X. High-sensitivity special open-cavity Mach-Zehnder structure for salinity measurement based on etched double-side hole fiber: publisher's note. OPTICS LETTERS 2021; 46:3069. [PMID: 34197381 DOI: 10.1364/ol.433096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Indexed: 06/13/2023]
Abstract
This publisher's note contains corrections to Opt. Lett.46, 2714 (2021).OPLEDP0146-959210.1364/OL.428001.
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