We propose and demonstrate an all-fiber liquid-level sensor using an in-line multimode-single-mode-multimode (MSM) fiber structure. A piece of single-mode fiber (SMF) is spliced to two sections of equivalent multimode fiber (MMF) which are used as both mode splitter and mode coupler. The cladding mode will be excited when the light propagates from MMF to SMF, and then it will be combined with fundamental mode to form a Mach-Zehnder interferometer (MZI) when the light propagates from SMF to the other MMF. The liquid level is detected by the selected resonant dips shift of the transmission spectrum. A sensing sensitivity of 264.6 pm/mm is achieved for the proposed sensor with an SMF length of 26mm. Due to its compact structure, easy fabrication, and high sensitivity, the proposed liquid-level sensor is attractive for practical applications in a variety of fields, such as marine detection and chemical processing.
K. Shannon, X. Li, Z. Wang, and J. D. N. Cheeke, “Mode conversion and the path of acoustic energy in a partially water-filled aluminum tube,” Ultrasonics, 1999, 37(4): 303–307.
F. Reverter, X. J. Li, and G. C. M. Meijer, “Liquid-level measurement system based on a remote grounded capacitive sensor,” Sensors and Actuators A: Physical, 2007, 138(1): 1–8.
B. W. Northway, N. H. Hancock, and T. Tran-cong, “Liquid level sensors using thin walled cylinders vibrating in circumferential modes,” Measurement Science & Technology, 1995, 6(1): 85.
Y. S. Zhang, W. G. Zhang, L. Chen, Y. X. Zhang, S. Wang, and T. Y. Yan, “High sensitivity optical fiber liquid level sensor based on compact MMF-HCF-FBG structure,” Measurement Science and Technology, 2018, 29(5): 055104.
N. S. Fabián, A. B. Socorro-Leránoz, I. D. Villar, S. Díaz, and I. R. Matías, “Multimode-coreless-multimode fiber-based sensors: theoretical and experimental study,” Journal of Lightwave Technology, 2019, 37(15): 3844–3850.
K. Iwamoto and I. Kamata, “Liquid-level sensor with optical fibers,” Applied Optics, 1992, 31(1): 51–54.
T. Guo, Q. D. Zhao, Q. Y. Dou, H. Zhang, L. F. Xue, G. L. Ling, et al., “Temperature-insensitive fiber Bragg grating liquid-level sensor based on bending cantilever beam,” IEEE Photonics Technology Letters, 2005, 17(11): 2400–2402.
K. R. Sohn and J. H. Shim, “Liquid-level monitoring sensor systems using fiber Bragg grating embedded in cantilever,” Sensors and Actuators A: Physical, 2009, 152(2): 248–251.
H. Y. Fu, X. W. Shu, A. P. Zhang, W. S. Liu, L. Zhang, S. L. He, et al., “Implementation and characterization of liquid-level sensor based on a long-period fiber grating Mach-Zehnder interferometer,” IEEE Sensors Journal, 2011, 11(11): 2878–2882.
Y. Huang, B. K. Chen, G. D. Chen, H. Xiao, and S. U. Khan, “Simultaneous detection of liquid level and refractive index with a long-period fiber grating based sensor device,” Measurement Science and Technology, 2013, 24(9): 095303.
B. B. Gu, W. L. Qi, Y. Y. Zhou, Z. F. Wu, P. P. Shum, and F. Luan, “Reflective liquid level sensor based on modes conversion in thin-core fiber incorporating tilted fiber Bragg grating,” Optics Express, 2014, 22(10): 11834–11839.
T. Osuch, T. Jurek, K. Markowski, and K. Jedrzejewski, “Simultaneous measurement of liquid level and temperature using tilted fiber Bragg grating,” IEEE Sensors Journal, 2015, 16(5): 1205–1209.
C. Li, T. G. Ning, C. Zhang, J. Li, X. D. Wen, L. Pei, et al., “Liquid level measurement based on a no-core fiber with temperature compensation using a fiber Bragg grating,” Sensors and Actuators A: Physical, 2016, 245: 49–53.
Y. Q. Wen, L. Xia, Y. L. Ran, J. Rohollahnejad, and D. M. Liu, “All-fiber in-line SNS structure liquid level sensor,” Asia Communications and Photonics Conference 2015, Hong Kong, Nov. 19–23, 2015.
H. Y. Choi, M. J. Kim, and B. H. Lee, “All-fiber Mach-Zehnder type interferometers formed in photonic crystal fiber,” Optics Express, 2007, 15(9): 5711–5720.
T. Lü and S. Yang, “Extrinsic Fabry-Perot cavity optical fiber liquid-level sensor,” Applied Optics, 2007, 46(18): 3682–3687.
C. W. Lai, Y. L. Lo, J. P. Yur, W. F. Liu, and C. H. Chuang, “Application of Fabry-Perot and fiber Bragg grating pressure sensors to simultaneous measurement of liquid level and specific gravity,” Measurement, 2012, 45(3): 469–473.
M. M. Sun, Y. X. Jin, and X. Y. Dong, “All-fiber Mach-Zehnder interferometer for liquid level measurement,” IEEE Sensors Journal, 2015, 15(7): 3984–3988.
Q. Wu, Y. Semenova, B. B. Yan, Y. Q. Ma, P. F. Wang, C. X. Yu, et al., “Fiber refractometer based on a fiber Bragg grating and single-modemultimode-single-mode fiber structure,” Optics Letters, 2011, 36(12): 2197–2199.
Z. L. Xu, Q. Z. Sun, J. H. Wo, Y. Dai, X. L. Li, and D. M. Liu, “Volume strain sensor based on spectra analysis of in-fiber modal interferometer,” IEEE Sensors Journal, 2013, 13(6): 2139–2145.
J. H. Wo, Q. Z. Sun, H. Liu, X. L. Li, J. J. Zhang, D. M. Liu, et al., “Sensitivity-enhanced fiber optic temperature sensor with strain response suppression,” Optical Fiber Technology, 2013, 19(4): 289–292.
Y. Gong, T. Zhao, Y. J. Rao, and Y. Wu, “All-fiber curvature sensor based on multimode interference,” IEEE Photonics Technology Letters, 2011, 23(11): 679–681.
This study was supported in part by the National Natural Science Foundation of China (NSFC) (Grant Nos. 61727816, 61520106013, and 61705031), in part by China Postdoctoral Science Foundation (Grant Nos. 2017M610175 and 2018T110216), in part by Fundamental Research Funds for Central Universities (Grant No. DUT19LAB32) Sponsor, and financial support acknowledgments are placed here.
About this article
Cite this article
Sun, T., Liu, Z., Liu, Y. et al. All-Fiber Liquid-Level Sensor Based on In-Line MSM Fiber Structure. Photonic Sens (2020). https://doi.org/10.1007/s13320-020-0586-1
- Liquid-level sensor
- MSM fiber structure
- optical fiber sensor