Research

15 pages, 3082 KiB

Open AccessArticle

Compact Interrogation System of Fiber Bragg Grating Sensors Based on Multiheterodyne Dispersion Interferometry for Dynamic Strain Measurements

by Dragos A. Poiana, Julio E. Posada-Roman and Jose A. Garcia-Souto

Sensors 2022, 22(9), 3561; https://0-doi-org.brum.beds.ac.uk/10.3390/s22093561 - 07 May 2022

Cited by 4 | Viewed by 1935

Abstract

Dual-comb multiheterodyne spectroscopy is a well-established technology for the highly sensitive real-time detection and measurement of the optical spectra of samples, including gases and fiber sensors. However, a common drawback of dual-comb spectroscopy is the need for a broadband amplitude-resolved absorption or reflection [...] Read more.

Dual-comb multiheterodyne spectroscopy is a well-established technology for the highly sensitive real-time detection and measurement of the optical spectra of samples, including gases and fiber sensors. However, a common drawback of dual-comb spectroscopy is the need for a broadband amplitude-resolved absorption or reflection measurement, which increases the complexity of the dual comb and requires the precise calibration of the optical detection. In the present study, we present an alternative dispersion-based approach applied to fiber Bragg grating sensors in which the dual comb is compacted by a single dual-drive-unit optical modulator, and the fiber sensor is part of a dispersion interferometer. The incident dual comb samples a few points in the spectrum that are sensitive to Bragg wavelength changes through the optical phase. The spectra reading is improved due to the external interferometer and is desensitized to changes in the amplitude of the comb tones. The narrow-band detection of the fiber sensor dispersion changes that we demonstrate enables the compact, cost-effective, high-resolution multiheterodyne interrogation of high-throughput interferometric fiber sensors. These characteristics open its application both to the detection of fast phenomena, such as ultrasound, and to the precise measurement at high speed of chemical-/biological-sensing samples. The results with a low-reflectivity fiber Bragg grating show the detection of dynamic strain in the range of 215 nε with a 30 dB signal to noise ratio and up to 130 kHz (ultrasonic range). Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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19 pages, 8243 KiB

Open AccessCommunication

Distributed Acoustic Sensor Using a Double Sagnac Interferometer Based on Wavelength Division Multiplexing

by Andrey A. Zhirnov, Tatyana V. Choban, Konstantin V. Stepanov, Kirill I. Koshelev, Anton O. Chernutsky, Alexey B. Pnev and Valeriy E. Karasik

Sensors 2022, 22(7), 2772; https://0-doi-org.brum.beds.ac.uk/10.3390/s22072772 - 04 Apr 2022

Cited by 14 | Viewed by 2126

Abstract

We demonstrated a fiber optic distributed acoustic sensor based on a double Sagnac interferometer, using two wavelengths separated by CWDM modules. A mathematical model of signal formation principle, based on a shift in two signals analysis, was described and substantiated mathematically. The dependence [...] Read more.

We demonstrated a fiber optic distributed acoustic sensor based on a double Sagnac interferometer, using two wavelengths separated by CWDM modules. A mathematical model of signal formation principle, based on a shift in two signals analysis, was described and substantiated mathematically. The dependence of the sensor sensitivity on a disturbance coordinate and frequency was found and simulated, and helped determine a low sensitivity zone length and provided sensor scheme optimization. A data processing algorithm without filtering, appropriate even in case of a high system noise level, was described. An experimental study of the distributed fiber optic sensor based on a Sagnac interferometer with two wavelengths divided countering loops was carried out. An accuracy of 24 m was achieved for 25.4 km SMF sensing fiber without phase unwrapping. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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13 pages, 1623 KiB

Open AccessCommunication

A Review of Sensitivity Enhancement in Interferometer-Based Fiber Sensors

by Zengrun Wen, Ziqing Guan, Jingru Dong, Hongxin Li, Yangjian Cai and Song Gao

Sensors 2022, 22(7), 2506; https://0-doi-org.brum.beds.ac.uk/10.3390/s22072506 - 25 Mar 2022

Cited by 4 | Viewed by 2618

Abstract

Optical fiber sensors based on an interferometer structure play a significant role in monitoring physical, chemical, and biological parameters in natural environments. However, sensors with high-sensitivity measurement still present their own challenges. This paper deduces and summarizes the methods of sensitivity enhancement in [...] Read more.

Optical fiber sensors based on an interferometer structure play a significant role in monitoring physical, chemical, and biological parameters in natural environments. However, sensors with high-sensitivity measurement still present their own challenges. This paper deduces and summarizes the methods of sensitivity enhancement in interferometer based fiber optical sensors, including the derivation of the sensing principles, key characteristics, and recently-reported applications.The modal coupling interferometer is taken as an example to derive the five terms related to the sensitivity: (1) the wavelength-dependent difference of phase between two modes/arms

\partial ϕ_{d} / \partial λ

, (2) the sensor length

L_{w, A}

, (3) refractive index difference between two modes/arms

Δ n_{e f f, A}

, (4) sensing parameter dependent length change

α

, and (5) sensing parameter dependent refractive index change

γ

. The research papers in the literature that modulate these terms to enhance the sensing sensitivity are reviewed in the paper. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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11 pages, 5975 KiB

Open AccessArticle

Distributed Acoustic Sensing (DAS) Response of Rising Taylor Bubbles in Slug Flow

by Aleksei Titov, Yilin Fan, Kagan Kutun and Ge Jin

Sensors 2022, 22(3), 1266; https://0-doi-org.brum.beds.ac.uk/10.3390/s22031266 - 07 Feb 2022

Cited by 7 | Viewed by 3049

Abstract

Slug flow is one of the most common flow types encountered in surface facilities, pipelines, and wellbores. The intermittent gas phase, in the form of a Taylor bubble, followed by the liquid phase can be destructive to equipment. However, commonly used point flow [...] Read more.

Slug flow is one of the most common flow types encountered in surface facilities, pipelines, and wellbores. The intermittent gas phase, in the form of a Taylor bubble, followed by the liquid phase can be destructive to equipment. However, commonly used point flow sensors have significant limitations for flow analysis. Distributed acoustic sensing (DAS) can turn optical fibers into an array of distributed strain rate sensors and provide substantial insights into flow characterization. We built a 10 m vertical laboratory flow loop equipped with wrapped fiber optic cables to study the DAS response of rising Taylor bubbles. Low-passed DAS data allow for velocity tracking of Taylor bubbles of different sizes and water velocities. Moreover, we measured the velocity of the wake region following the Taylor bubble and explored the process of Taylor bubbles merging. The amplitude analysis of DAS data allows for the estimation of Taylor bubble size. We conclude that DAS is a promising tool for understanding Taylor bubble properties in a laboratory environment and monitoring destructive flow in facilities across different industries to ensure operations are safe and cost-effective. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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21 pages, 4289 KiB

Open AccessArticle

SARS-CoV-2 Detection Using Optical Fiber Based Sensor Method

by Muhammad Usman Hadi and Menal Khurshid

Sensors 2022, 22(3), 751; https://0-doi-org.brum.beds.ac.uk/10.3390/s22030751 - 19 Jan 2022

Cited by 14 | Viewed by 3075

Abstract

The SARS-CoV-2 Coronavirus disease, also known as the COVID-19 pandemic, has engendered the biggest challenge to human life for the last two years. With a rapid increase in the spread of the Omicron variant across the world, and to contain the spread of [...] Read more.

The SARS-CoV-2 Coronavirus disease, also known as the COVID-19 pandemic, has engendered the biggest challenge to human life for the last two years. With a rapid increase in the spread of the Omicron variant across the world, and to contain the spread of COVID-19 in general, it is crucial to rapidly identify this viral infection with minimal logistics. To achieve this, a novel plastic optical fiber (POF) U-shaped probe sensing method is presented for accurate detection of SARS-CoV-2, commonly known as the COVID-19 virus, which has the capability to detect new variants such as Omicron. The sample under test can be taken from oropharyngeal or nasopharyngeal via specific POF U-shaped probe with one end that is fed with a laser source while the other end is connected to a photodetector to receive the response and postprocess for decision-making. The study includes detection comparison with two types of POF with diameters of 200 and 500 µm. Results show that detection is better when a smaller-diameter POF is used. It is also seen that the proposed test bed and its envisaged prototype can detect the COVID-19 variants within 15 min of the test. The proposed approach will make the clinical diagnosis faster, cheaper and applicable to patients in remote areas where there are no hospitals or clinical laboratories due to poverty, geographic obstacles, or other factors. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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13 pages, 6557 KiB

Open AccessArticle

Liquid Resin Infusion Process Validation through Fiber Optic Sensor Technology

by Vincenzo Romano Marrazzo, Armando Laudati, Michele Vitale, Francesco Fienga, Gianni Iagulli, Marco Raffone, Andrea Cusano, Michele Giordano, Antonello Cutolo and Giovanni Breglio

Sensors 2022, 22(2), 508; https://0-doi-org.brum.beds.ac.uk/10.3390/s22020508 - 10 Jan 2022

Cited by 7 | Viewed by 2003

Abstract

In the proposed work, a fiber-optic-based sensor network was employed for the monitoring of the liquid resin infusion process. The item under test was a panel composed by a skin and four stringers, sensorized in such a way that both the temperature and [...] Read more.

In the proposed work, a fiber-optic-based sensor network was employed for the monitoring of the liquid resin infusion process. The item under test was a panel composed by a skin and four stringers, sensorized in such a way that both the temperature and the resin arrival could be monitored. The network was arranged with 18 Fiber Bragg Gratings (FBGs) working as temperature sensors and 22 fiber optic probes with a modified front-end in order to detect the resin presence. After an in-depth study to find a better solution to install the sensors without affecting the measurements, the system was investigated using a commercial Micron Optics at 0.5 Hz, with a passive split-box connected in order to be able to sense all the sensors simultaneously. The obtained results in terms of resin arrival detection at different locations and the relative temperature trend allowed us to validate an infusion process numerical model, giving us better understanding of what the actual resin flow was and the time needed to dry preform filling during the infusion process. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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17 pages, 7953 KiB

Open AccessArticle

Multichannel Approach for Arrayed Waveguide Grating-Based FBG Interrogation Systems

by Vincenzo Romano Marrazzo, Francesco Fienga, Michele Riccio, Andrea Irace and Giovanni Breglio

Sensors 2021, 21(18), 6214; https://0-doi-org.brum.beds.ac.uk/10.3390/s21186214 - 16 Sep 2021

Cited by 7 | Viewed by 1919

Abstract

In this manuscript, an optically passive fiber Bragg grating (FBG) interrogation system able to perform high-frequency measurement is proposed. The idea is mainly based on the use of an arrayed waveguide grating (AWG) device which is used to discriminate the fiber optic sensor [...] Read more.

In this manuscript, an optically passive fiber Bragg grating (FBG) interrogation system able to perform high-frequency measurement is proposed. The idea is mainly based on the use of an arrayed waveguide grating (AWG) device which is used to discriminate the fiber optic sensor (FOS) wavelength encoded response under test in function of its output channels. As made clear by the theoretical model studied in the proposed manuscript, the Bragg wavelength shift can be detected as in linear dependence with the proposed interrogation function which changes with the voltage produced by two (or more) adjacent AWG output channels. To prove the feasibility of the system, some experimental analyses are conducted with a custom electrical module characterized by high-speed and low-noise operational amplifiers. As static measurements, three FBGs with different full width at half maximum (FWHM) have been monitored under wide-range wavelength variation; while, as dynamic measurement, one FBG, glued onto a metal plate, in order to sense the vibration at low and high frequency, was detected. The output signals have been processed by a digital acquisition (DAQ) board and a graphical user interface (GUI). The presented work highlights the characteristics of the proposed idea as competitor among the entire class of interrogation systems currently used. This is because here, the main device, that is the AWG, is passive and reliable, without the need to use modulation signals, or moving parts, that affect the speed of the system. In addition, the innovative multi-channel detection algorithm allows the use of any type of FOS without the need to have a perfectly match of spectra. Moreover, it is also characterized by a high dynamic range without loss of sensitivity. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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15 pages, 1276 KiB

Open AccessArticle

An Optimized Self-Compensated Solution for Temperature and Strain Cross-Sensitivity in FBG Interrogators Based on Edge Filter

by Mariana L. Silveira, Helder R. O. Rocha, Paulo F. C. Antunes, Paulo S. B. André, Marcelo E. V. Segatto, Anselmo Frizera and Camilo A. R. Díaz

Sensors 2021, 21(17), 5828; https://0-doi-org.brum.beds.ac.uk/10.3390/s21175828 - 30 Aug 2021

Cited by 5 | Viewed by 2061

Abstract

Optical fiber sensors based on fiber Bragg gratings (FBGs) are prone to measurement errors if the cross-sensitivity between temperature and strain is not properly considered. This paper describes a self-compensated technique for canceling the undesired influence of temperature in strain measurement. An edge-filter-based [...] Read more.

Optical fiber sensors based on fiber Bragg gratings (FBGs) are prone to measurement errors if the cross-sensitivity between temperature and strain is not properly considered. This paper describes a self-compensated technique for canceling the undesired influence of temperature in strain measurement. An edge-filter-based interrogator is proposed and the central peaks of two FBGs (sensor and reference) are matched with the positive and negative slopes of a Fabry–Perot interferometer that acts as an optical filter. A tuning process performed by the grey wolf optimizer (GWO) algorithm is required to determine the optimal spectral characteristics of each FBG. The interrogation range is not compromised by the proposed technique, being determined by the spectral characteristics of the optical filter in accordance with the traditional edge-filtering interrogation. Simulations show that, by employing FBGs with optimal characteristics, temperature variations of 30 °C led to an average relative error of 3.4% for strain measurements up to 700μϵ. The proposed technique was experimentally tested under non-ideal conditions: two FBGs with spectral characteristics different from the optimized results were used. The temperature sensibility decreased by 50.8% as compared to a temperature uncompensated interrogation system based on an edge filter. The non-ideal experimental conditions were simulated and the maximum error between theoretical and experimental data was 5.79%, proving that the results from simulation and experimentation are compatible. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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9 pages, 3589 KiB

Open AccessCommunication

Distributed Static and Dynamic Strain Measurements in Polymer Optical Fibers by Rayleigh Scattering

by Agnese Coscetta, Ester Catalano, Enis Cerri, Ricardo Oliveira, Lucia Bilro, Luigi Zeni, Nunzio Cennamo and Aldo Minardo

Sensors 2021, 21(15), 5049; https://0-doi-org.brum.beds.ac.uk/10.3390/s21155049 - 26 Jul 2021

Cited by 6 | Viewed by 1968

Abstract

We demonstrate the use of a graded-index perfluorinated optical fiber (GI-POF) for distributed static and dynamic strain measurements based on Rayleigh scattering. The system is based on an amplitude-based phase-sensitive Optical Time-Domain Reflectometry (ϕ-OTDR) configuration, operated at the unconventional wavelength of 850 nm. [...] Read more.

We demonstrate the use of a graded-index perfluorinated optical fiber (GI-POF) for distributed static and dynamic strain measurements based on Rayleigh scattering. The system is based on an amplitude-based phase-sensitive Optical Time-Domain Reflectometry (ϕ-OTDR) configuration, operated at the unconventional wavelength of 850 nm. Static strain measurements have been carried out at a spatial resolution of 4 m and for a strain up to 3.5% by exploiting the increase of the backscatter Rayleigh coefficient consequent to the application of a tensile strain, while vibration/acoustic measurements have been demonstrated for a sampling frequency up to 833 Hz by exploiting the vibration-induced changes in the backscatter Rayleigh intensity time-domain traces arising from coherent interference within the pulse. The reported tests demonstrate that polymer optical fibers can be used for cost-effective multiparameter sensing. Full article

(This article belongs to the Special Issue Pervasive Fiber Optic Sensor Technology: Improvements and Applications)

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