Special Issue "Fiber Bragg Gratings: Fundamentals, Materials and Applications"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (31 January 2019)

Special Issue Editor

Guest Editor
Prof. Dr. Ralf Hellmann

Applied Laser and Photonics Group, University of Applied Science Aschaffenburg, Wuerzburger Strasse 45, D-63743 Aschaffenburg, Germany
Website | E-Mail
Interests: applied optics and lasers; Bragg Grating based sensors; laser material processing; additive manufacturing; nanotechnology; applied materials

Special Issue Information

Dear Colleagues,

Ever since their first observation, Fiber Bragg Gratings (FBG) have become a technically-mature technology in both optical communication and sensing. However, continuous research is ongoing to address both fundamental and application related topics of the particular photonic structure. This Special Issue “Fiber Bragg Gratings: Fundamentals, Materials and Applications” will concentrate on all aspects of fundamental and applied research with a particular focus on photonics. Both, original research papers, as well as review papers, are welcome.

Topics of interests include, but are not limited to:

  • Fabrication of Fiber Bragg Grating (techniques, materials, grating types)

  • Bragg gratings in specialty fibers and planar substrates

  • Integration and Packaging of FBGs

  • Advances in interrogation systems (low cost, high-speed)

  • Modeling and simulation of Fiber Bragg Grating

  • Photonic applications (filters, amplifiers, lasers, sensors)

  • Fiber Bragg Grating based integrated photonic systems

  • Novel applications

The objective of this Special Issue is to compile and spotlight both the fundamentals of Fiber Bragg Grating technologies and applications, as well as interdisciplinary topical photonic trends of Bragg Grating research.

Prof. Ralf Hellmann
Guest Editor

Manuscript Submission Information

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Keywords

  • Fabrication of Fiber Bragg Grating (techniques, materials, grating types)

  • Bragg gratings in specialty fibers and planar substrates

  • Integration and Packaging of FBGs

  • Advances in interrogation systems (low cost, high-speed)

  • Modeling and simulation of Fiber Bragg Grating

  • Photonic applications (filters, amplifiers, lasers, sensors)

  • Fiber Bragg Grating based integrated photonic systems

  • Novel applications

Published Papers (8 papers)

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Research

Open AccessArticle Temperature Sensing of Stepped-Metal Coated Optical Fiber Bragg Grating with the Restructured Dual-Peak Resonance
Appl. Sci. 2019, 9(2), 286; https://doi.org/10.3390/app9020286
Received: 19 December 2018 / Revised: 11 January 2019 / Accepted: 11 January 2019 / Published: 15 January 2019
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Abstract
This paper demonstrates a method for the development of stepped-metal coating on optical fiber Bragg grating. The paper also analyzes the dual-peak resonance restructured by the nickel/copper stepped-metal coating. According to the coefficients of linear thermal expansion of the coatings, the modeling and [...] Read more.
This paper demonstrates a method for the development of stepped-metal coating on optical fiber Bragg grating. The paper also analyzes the dual-peak resonance restructured by the nickel/copper stepped-metal coating. According to the coefficients of linear thermal expansion of the coatings, the modeling and experimental analysis is categorized into three types: Type A, Type B, and Type C. We denote the temperature sensitivity difference between the two peaks as ΔKT for Type A, ΔKT for Type B, and ΔKT for Type C. The experimental results show that ΔKT, ΔKT, and ΔKT are 2.1 pm/°C, 6.5 pm/°C, and 0.8 pm/°C, respectively. The model analysis and the experimental results all show the Type B stepped-metal coating causes the most obvious temperature sensitivity difference between the two resonance peaks. The stepped-metal coating on the same one Bragg grating can restructure the single resonance into dual-peak resonance with different temperature sensing, and Type B can be used to develop a dual-parameter optical fiber Bragg grating sensor at one location which can measure two physical parameters simultaneously. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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Open AccessArticle A Temperature Fiber Sensor Based on Tapered Fiber Bragg Grating Fabricated by Femtosecond Laser
Appl. Sci. 2018, 8(12), 2616; https://doi.org/10.3390/app8122616
Received: 10 October 2018 / Revised: 7 December 2018 / Accepted: 10 December 2018 / Published: 14 December 2018
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Abstract
A temperature fiber sensor based on tapered fiber Bragg grating (tapered FBG) fabricated by femtosecond laser has been proposed and realized with good reproducibility. Firstly, the fiber taper with 25 μm diameter and 1000 μm length is fabricated by arc-discharge elongation using two [...] Read more.
A temperature fiber sensor based on tapered fiber Bragg grating (tapered FBG) fabricated by femtosecond laser has been proposed and realized with good reproducibility. Firstly, the fiber taper with 25 μm diameter and 1000 μm length is fabricated by arc-discharge elongation using two standard single-mode fibers. Secondly, two first-order FBGs are fabricated in tapered and non-tapered fiber regions for comparison. Both FBGs are point-by-point direct-written by femtosecond laser, and the grating lengths are 1000 μm. Thirdly, a temperature experiment is performed using a heating chamber, and experimental results show that in the range of 30~350 °C, the temperature sensitivity of the tapered FBG has increased from 11.0 pm/°C to 12.3 pm/°C. The tapered FBG proposed here can be further configured for sensing other parameters in physical, chemical, and biomedical applications. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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Open AccessArticle Passively Conducted Vibration Sensing with Fiber Bragg Gratings
Appl. Sci. 2018, 8(9), 1599; https://doi.org/10.3390/app8091599
Received: 14 July 2018 / Revised: 22 August 2018 / Accepted: 28 August 2018 / Published: 10 September 2018
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Abstract
Measuring vibrations is a common method of monitoring the integrity of structures and heavy machinery, that are subject to dynamic loads. Strong vibrations for prolonged periods of time can be caused by various sources, such as trains, motors and heavy machinery. These strong [...] Read more.
Measuring vibrations is a common method of monitoring the integrity of structures and heavy machinery, that are subject to dynamic loads. Strong vibrations for prolonged periods of time can be caused by various sources, such as trains, motors and heavy machinery. These strong vibrations should be identified and managed to ensure operational safety. This study proposes a flexible metal beam sensor with a fiber Bragg grating (FBG) mounted on the surface to measure the vibrational frequency. We present a sensor for measuring the vibrational frequencies on-site by placing the beam so that it makes physical contact with the vibrating body. The sensor has been tested in the range of 50–200 Hz. The sensing beam can detect the vibrations that are induced in other metallic bodies where there are metallic structures of low stiffness to conduct the vibration. The results show that the sensing beam is capable of detecting the frequency of forced vibrations from its periphery when placed in different orientations. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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Open AccessArticle Strain Transfer Characteristic of a Fiber Bragg Grating Sensor Bonded to the Surface of Carbon Fiber Reinforced Polymer Laminates
Appl. Sci. 2018, 8(7), 1171; https://doi.org/10.3390/app8071171
Received: 13 June 2018 / Revised: 13 July 2018 / Accepted: 16 July 2018 / Published: 18 July 2018
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Abstract
Structural health monitoring is of great importance for the application of composites in aircrafts. Fiber Bragg grating (FBG) sensors are very suitable for structure strain measurement. However, the strain measured by FBG sensors is different from the original strain in host materials. The [...] Read more.
Structural health monitoring is of great importance for the application of composites in aircrafts. Fiber Bragg grating (FBG) sensors are very suitable for structure strain measurement. However, the strain measured by FBG sensors is different from the original strain in host materials. The relationship between them is defined as strain transfer. As composites are anisotropic, the traditional strain transfer model, which regards the elasticity modulus of host materials as a constant, is inadaptable. In this paper, a new strain transfer model is proposed for FBG sensors bonded to the surface of carbon fiber reinforced polymer (CFRP) laminates. Based on the measurement structure, the model is established and the transfer function is derived. The characteristics influencing the strain transfer are analyzed. The stacking directions, stacking numbers, and stacking sequences of CFRP laminates have a distinct effect on the transfer efficiency, which is different from the isotropy host materials. The accuracy of the proposed model was verified by experiments on a nondestructive tensile system, and the maximum model error is less than 0.5%. Moreover, the model was applied to the strain measurement of CFRP wing skin, which indicates that measurement errors decrease by 11.6% to 19.8% after the compensation according to the model. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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Open AccessArticle An Indirect Method for Monitoring Dynamic Deflection of Beam-Like Structures Based on Strain Responses
Appl. Sci. 2018, 8(5), 811; https://doi.org/10.3390/app8050811
Received: 10 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
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Abstract
An indirect method for monitoring dynamic deflection of beam-like structures using strain responses measured by long-gauge fiber Bragg grating (FBG) sensors is proposed in this paper. Firstly, a theoretical derivation shows that structural deflection is in direct and linear relationship to long-gauge strain. [...] Read more.
An indirect method for monitoring dynamic deflection of beam-like structures using strain responses measured by long-gauge fiber Bragg grating (FBG) sensors is proposed in this paper. Firstly, a theoretical derivation shows that structural deflection is in direct and linear relationship to long-gauge strain. Meanwhile, the method is suitable for structures with different boundary conditions and irrelevant to external loads. Secondly, the influence of boundary conditions, load type and sensor gauge length on the method is investigated by numerical simulation. Finally, an experiment of a simply supported beam subjected to dynamic loads was designed to verify the method. Experimental results show that both deflection time-history of arbitrary points of structures and deflection distribution along structures at a certain time can be obtained with high-precision. Therefore, the method presented can be a new alternative for the deflection evaluation and maintenance of engineering structures. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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Open AccessArticle Design and Optimization of an Opened Suspended Core Fiber-Based SPR Sensor with Gold Cylinder Structures
Appl. Sci. 2018, 8(4), 592; https://doi.org/10.3390/app8040592
Received: 22 February 2018 / Revised: 1 April 2018 / Accepted: 3 April 2018 / Published: 9 April 2018
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Abstract
In this study, an opened three-hole suspended core fiber surface plasmon resonance sensor structure based on the combination of photonic crystal fiber and surface plasmon resonance (SPR) mechanism was proposed and analyzed. One hole in the clad layer was exposed to the outside, [...] Read more.
In this study, an opened three-hole suspended core fiber surface plasmon resonance sensor structure based on the combination of photonic crystal fiber and surface plasmon resonance (SPR) mechanism was proposed and analyzed. One hole in the clad layer was exposed to the outside, and a lay of gold cylinders with the same size and gap was placed along the inside of the opened hole. The existence of the gold cylinders could stimulate the SPR effect and selecting the suitable gaps between the cylinders could enhance the SPR effect and increase its sensitivity. Then COMSOL software was used to simulate how the cylinder diameter, the gaps between the cylinders, and the fluid refractive index variation affect the sensor’s transmission loss spectrum, field enhancement effect, and the sensitivity. The optimized results show that the sensitivity of this proposed SPR sensor could be high, up to 1 × 10−5 RIU/nm, and it was much higher than the sensitivity of the existing photonic crystal fiber SPR sensor (1 × 10−4 RIU/nm), which was an order of magnitude improvement. This study could provide a reliable theoretical basis for future research and design of real-time and high-sensitivity opened fiber SPR sensors. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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Open AccessArticle Pipeline Leak Localization Based on FBG Hoop Strain Sensors Combined with BP Neural Network
Appl. Sci. 2018, 8(2), 146; https://doi.org/10.3390/app8020146
Received: 14 December 2017 / Revised: 11 January 2018 / Accepted: 19 January 2018 / Published: 24 January 2018
Cited by 4 | PDF Full-text (2857 KB) | HTML Full-text | XML Full-text
Abstract
Pipelines function as blood vessels serving to bring life-necessities, so their safe usage is one of the foremost concerns. In our previous work, a fiber Bragg grating (FBG) hoop strain sensor with enhanced sensitivity was developed to measure the pressure drop induced by [...] Read more.
Pipelines function as blood vessels serving to bring life-necessities, so their safe usage is one of the foremost concerns. In our previous work, a fiber Bragg grating (FBG) hoop strain sensor with enhanced sensitivity was developed to measure the pressure drop induced by pipeline leakage. Some hoop strain information during the leakage transient process can be extracted from the amount of FBG hoop strain sensors set along the pipeline. In this paper, an integrated approach of a back-propagation (BP) neural network and hoop strain measurement is first proposed to locate the leak points of the pipeline. Five hoop strain variations are employed as input neurons to achieve pattern recognition so as to predict the leakage point. The RMS error can be as low as 1.01% when choosing appropriate hidden layer neurons. Furthermore, the influence of noise on the network’s performance is investigated through superimposing Gaussian noise with a different level. The results demonstrate the feasibility and robustness of the neural network for pipeline leakage localization. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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Open AccessArticle Application of Fiber Bragg Grating Sensing Technology for Bolt Force Status Monitoring in Roadways
Appl. Sci. 2018, 8(1), 107; https://doi.org/10.3390/app8010107
Received: 21 December 2017 / Revised: 8 January 2018 / Accepted: 11 January 2018 / Published: 12 January 2018
Cited by 6 | PDF Full-text (2911 KB) | HTML Full-text | XML Full-text
Abstract
Bolts support have become a major active support method in coal mine roadways to control roadway roof failure and improve surrounding rock structure stability. The traditional bolt force status monitoring (BFSM) method has poor anti-interference performance, is easily affected by harsh downhole environments, [...] Read more.
Bolts support have become a major active support method in coal mine roadways to control roadway roof failure and improve surrounding rock structure stability. The traditional bolt force status monitoring (BFSM) method has poor anti-interference performance, is easily affected by harsh downhole environments, and cannot support remote real-time monitoring. This paper presents a fiber Bragg grating (FBG) bolt force sensor that monitors the force of roadway bolts. This sensor uses a cantilever and a diaphragm as elastic elements and two FBGs bonded on the top and bottom surfaces of the cantilever as sensing elements. The experimental results indicate that the measuring sensitivity is improved by using the center wavelength difference between the two FBGs. The sensitivity is 38.79 pm/kN within the range from 0 to 150 kN, and the correlation coefficient reaches 99.98%. The engineering applications show that the FBG sensing technology can automatically acquire, and monitoring results are of great significance in roadway anchorage engineering safety and bolt support quality evaluation. Furthermore, such a sensor is also widely used in quasi-distributed measurement and long-term online monitoring of bolt force status in such fields as geotechnical engineering, tunnel engineering, and slope engineering. Full article
(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)
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