Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating

In this work, we propose a fiber Bragg grating (FBG)-based sensor for curvature measurements. Two gratings are inscribed through the protective coating in a specialty optical fiber using focused femtosecond laser pulses and point-by-point direct writing technology. One grating is inscribed on the ce...

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Main Authors: Ruibin Chen, Lutian Li, Qianqing Yu, Zhijun Luo, Zhenggang Lian, Chuanxin Teng, Hang Qu, Xuehao Hu
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Micromachines
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Online Access:https://www.mdpi.com/2072-666X/15/11/1310
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author Ruibin Chen
Lutian Li
Qianqing Yu
Zhijun Luo
Zhenggang Lian
Chuanxin Teng
Hang Qu
Xuehao Hu
author_facet Ruibin Chen
Lutian Li
Qianqing Yu
Zhijun Luo
Zhenggang Lian
Chuanxin Teng
Hang Qu
Xuehao Hu
author_sort Ruibin Chen
collection DOAJ
description In this work, we propose a fiber Bragg grating (FBG)-based sensor for curvature measurements. Two gratings are inscribed through the protective coating in a specialty optical fiber using focused femtosecond laser pulses and point-by-point direct writing technology. One grating is inscribed on the central core adjacent to an air channel, while the other is inscribed on the eccentric core. The bending characteristics of the two-core fiber strongly depend on the bending direction due to the asymmetry of the fiber cores. A bending sensitivity of 58 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">p</mi><mi mathvariant="normal">m</mi><mo>/</mo><msup><mrow><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></semantics></math></inline-formula> is achieved by the FBG in the eccentric fiber core over the curvature range of 0–50 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></semantics></math></inline-formula>. Temperature and humidity cross-sensitivity could be significantly reduced by analyzing the differences in peak shifts between the two gratings. The sensor features a large sensing range and good robustness due to the presence of its protective buffer coating, which makes it a good candidate for curvature sensing in engineering fields.
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spelling doaj-art-10e94b7e18d144f4a092f02beebd05f32025-08-20T01:54:03ZengMDPI AGMicromachines2072-666X2024-10-011511131010.3390/mi15111310Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective CoatingRuibin Chen0Lutian Li1Qianqing Yu2Zhijun Luo3Zhenggang Lian4Chuanxin Teng5Hang Qu6Xuehao Hu7Research Center for Advanced Optics and Photoelectronics, Department of Physics, College of Science, Shantou University, Shantou 515063, ChinaResearch Center for Advanced Optics and Photoelectronics, Department of Physics, College of Science, Shantou University, Shantou 515063, ChinaYangtze Optical Electronics Co., Ltd., East Lake Hi-Tech Developzone, Wuhan 430205, ChinaYangtze Optical Electronics Co., Ltd., East Lake Hi-Tech Developzone, Wuhan 430205, ChinaYangtze Optical Electronics Co., Ltd., East Lake Hi-Tech Developzone, Wuhan 430205, ChinaGuangxi Key Laboratory of Optoelectronic Information Processing, Guilin University of Electronic Technology, Guilin 541004, ChinaResearch Center for Advanced Optics and Photoelectronics, Department of Physics, College of Science, Shantou University, Shantou 515063, ChinaDepartment of Electromagnetism and Telecommunication, University of Mons, Boulevard Dolez 31, 7000 Mons, BelgiumIn this work, we propose a fiber Bragg grating (FBG)-based sensor for curvature measurements. Two gratings are inscribed through the protective coating in a specialty optical fiber using focused femtosecond laser pulses and point-by-point direct writing technology. One grating is inscribed on the central core adjacent to an air channel, while the other is inscribed on the eccentric core. The bending characteristics of the two-core fiber strongly depend on the bending direction due to the asymmetry of the fiber cores. A bending sensitivity of 58 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">p</mi><mi mathvariant="normal">m</mi><mo>/</mo><msup><mrow><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></semantics></math></inline-formula> is achieved by the FBG in the eccentric fiber core over the curvature range of 0–50 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></semantics></math></inline-formula>. Temperature and humidity cross-sensitivity could be significantly reduced by analyzing the differences in peak shifts between the two gratings. The sensor features a large sensing range and good robustness due to the presence of its protective buffer coating, which makes it a good candidate for curvature sensing in engineering fields.https://www.mdpi.com/2072-666X/15/11/1310two-core fiberFBGcurvature measurements
spellingShingle Ruibin Chen
Lutian Li
Qianqing Yu
Zhijun Luo
Zhenggang Lian
Chuanxin Teng
Hang Qu
Xuehao Hu
Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating
Micromachines
two-core fiber
FBG
curvature measurements
title Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating
title_full Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating
title_fullStr Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating
title_full_unstemmed Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating
title_short Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating
title_sort large range curvature measurement using fbgs in two core fiber with protective coating
topic two-core fiber
FBG
curvature measurements
url https://www.mdpi.com/2072-666X/15/11/1310
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