Fiber Optic Sensor Technology Research Articles

Enhancing milk quality assessment: A novel approach using an optical tongue with fiber-based Mach–Zehnder interferometry

The incorporation of advanced technologies in agricultural industry procedures has boosted operational efficiency, enabling more effective data collection and analysis. In this study, we developed an ”optical tongue” using fiber-optic Mach–Zehnder interferometers (MZIs) built from micro tapered long-period fiber gratings (MT-LPFGs). This tool was employed to collect data related to milk quality, with results indicating a high potential to improve the quality control of dairy products. These advances demonstrate the potential of optical fiber sensor technologies in the agricultural industry and quality control.

Innovative Early Detection of High-Temperature Abuse of Prismatic Cells and Post-Abuse Degradation Analysis Using Pressure and External Fiber Bragg Grating Sensors

Innovative Early Detection of High-Temperature Abuse of Prismatic Cells and Post-Abuse Degradation Analysis Using Pressure and External Fiber Bragg Grating Sensors

Room temperature fiber optic gas sensor technology based Zn3(VO4)2/PMMA hybrid composites via facile hydrothermal route

In this study, the authors present a simple hydrothermal method for obtaining Zn3(VO4)2 nanoparticles encapsulated in a polymethyl-metha-acrylate (PMMA) matrix. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and boron nitride zeta potential were used to determine the structural, topological, and porosity characteristics, respectively. The materials' gas-sensing properties were evaluated using a clad-modified optical fibre sensor. Ammonia, hydrogen sulphide, ethanol, and acetone were used to assess the detecting capabilities of the clad-modified sensing devices. Concentration ranges from 0 to 1000 ppm were tested at RT using both pure and Zn3(VO4)2/PMMA sensors. Zn3(VO4)2 nanopowder-modified fibre optic gas sensors show high sensitivity to ammonia gas at room temperature. The results show that nanocrystalline Zn3(VO4)2/PMMA has the fastest response time (22.4 min) and the longest recovery time (31.5 min) to ammonia (127 counts/Kpa). These results show that the Zn3(VO4)2/PMMA-based clad-removed sensors produced in this study are a highly efficient, potential choice for real-world ammonia sensing.

Pile defect assessment using distributed temperature sensing: fundamental questions examined

Thermal integrity testing has been successfully used to assess the quality of cast-in-place piles for the past decade. It employs temperature data measured during concrete curing to identify defects along the piles’ length. However, the uptake of this technology has been rather limited in the piling industry. The main concerns are that the method is not standardised and its reliability is not well understood. In order to address these, there are a number of fundamental questions that need to be explored in more detail, including (a) the optimum time to conduct the assessment, (b) the defect thermal impact, (c) the zone of influence on temperature sensors, (d) the minimum detectable size of a defect and (e) the associated optimum sensor location required. In this paper, experimental and numerical studies were conducted to examine these questions. Fibre optic sensors were employed on model concrete piles in laboratory tests to provide fully distributed temperature data throughout the curing process. The test results showed that the optimum time to assess the defects is approximately at 60% of the time to reach peak temperature and the minimal detectable defect size, using the currently available optical fibre sensor technology, is 4% of the cross-sectional area. In addition, the thermal influence of different defect sizes is presented. Following this, it is shown in the paper that the minimum numbers of sensor cables required to identify defects with cross-sectional areas of 4%, 5% and 8% are eight, six and four cables, respectively. The optimum layout of these sensor cables within a pile cross-section has also been discussed. When specifying pile instrumentation for integrity assessment, the findings of this paper enable practising engineers to make informed judgements in relation to the size of defects they would like to detect (and hence the associated risk this entails) together with the corresponding instrumentation layout required.

Study the Dispersion and Losses in Fiber Optics Communication

This paper presents the dispersion of optical fiber in terms of mode of dispersion, attenuation, and losses, etc including optical fiber in terms of introduction, which gives an overview of the optical fiber, including the classifications, type, attenuation losses, etc. Some basic optical fiber sensor technologies are also reviewed .under this study the different types of sensors that introduced the principle and different types of optical sensors based on sensing location i.e. extrinsic and intrinsic sensors, based on operating principles i.e.ProcessinvolvingDemodulation, Sensor based on Intensity Modulation, SensorsbasedonPhase Modulation, Sensors based on Polarization Modulation, Sensors based on Wavelength Modulation, which are constructedonapplicationthatcanmeasure temperature, stress, pH, blood flow along with glucose content.

Optical fiber sensors in infrastructure monitoring: a comprehensive review

Abstract The purpose of this article is to review and further promote the application of optical fiber sensor technology in infrastructure monitoring. Compared with traditional sensors, optical fiber sensors have low maintenance costs and are small in size; consequently, they have gradually become a future development direction of sensors. This paper introduces the basic principles of several commonly used optical fiber sensors and the progress of optical fiber sensors in the monitoring of physical, mechanical, and chemical parameters and demonstrates the applications of optical fiber sensors in infrastructure.

Detection of road vehicles at a railway level crossing by means of optical fiber distributed sensor

The exploit of distributed optical fiber sensor technology for vibration source detection in a railway environment using standard telecommunication cables is a new area of research with great potential. In this work, the detection of vehicles passing at a railway level crossing in the south of France is investigated by analyzing optical signals from an optical fiber sensor system. The results show high reliability and accuracy in detecting vehicles along with their direction at the level crossing. There is a correlation indicating a possible linearity between the vehicle's weight and the signal, we even were able to visually classify vehicles into three different categories according to their weight. These results are promising and opening the way for further work on automation and real-time analysis.

Innovative safety monitoring system based on fiber optic sensors technology compatible with 4-20mA standard

In this contribution an innovative, full analog, fiber optic sensors (FOS) interrogator is designed which, being fully compatible with the 4-20 mA standard of the Programmable Logic Controller (PLC), enable the integration of the FOS technology in safety framework, such as the Detector Safety System (DSS) of the LHC Experiments. It is composed by a full analog electrical circuitry, capable to directly transduce the signal coming from the arrayed waveguide grating (AWG), into a monotonic electrical current in the range of 4-20mA. In a first experimental analysis, a temperature of 50°C was detected, exhibiting an output trend which can be fitted with a 3rd order polynomial equation over the whole range. Furthermore, in a reduced range of 20°C, the trend behaves linearly. The proposed system has the potential to be fully integrated in the DSS of the LHC experiments. Indeed, a validation on field is foreseen in the framework of the Compact Muon Solenoid experiment DSS.

Raman scattering-based distributed temperature sensors: A comprehensive literature review over the past 37 years and towards new avenues

Over the last 37 years, particular interest has been directed towards exploring the characteristics of the optical environment for sensing, giving rise to what would now be one of the largest applications of well-known optical fibers, typically employed to transmit data at high rates. Sensing temperature, pressure, liquid level, deformation, and other physical parameters utilizing optical fibers has become a growing branch of research and a business competing with well-established electrical sensors in the industry. Optical fiber sensors have all the inherent characteristics of a fiber optic cable, such as electromagnetic immunity, small size and weight, multiplexing, and so on. These exclusive features have made fiber sensors so versatile as to become a transformative technology by enabling several industrial processes to be carried out with higher reliability. Nowadays, there are several optical sensors, including fiber Bragg grating, interferometric, polarimetric, polymer fiber, distributed, and several others. Specifically, Raman-based distributed temperature sensor (RDTS) is a class of fiber optic sensors broadly employed in temperature measurement of large structures such as oil and gas wells, tunnels, and pipelines. Since 1985, many techniques have been proposed to break through the barriers of exploring Raman scattering as a distributed temperature measurement method. Range, spatial and temperature resolutions have been the most investigated parameters. In this perspective, this paper presents a comprehensive review focused on the progress of the RDTS technology over the past 37 years (1985–2022), covering an analysis of over 500 journal papers. First, a brief introduction to fiber optic sensor technology is presented as a theoretical basis, discussing the emergence of distributed sensors. Subsequently, Raman scattering in optical fibers is introduced, as well as how this nonlinear effect can be used to build temperature sensors. Next, RDTS technology is detailed, followed by a discussion of its applications and evolution over nearly four decades of development. Lastly, future perspectives are addressed in this review for the advancements in distributed temperature sensor technologies.

Simultaneous interrogation of multiple cores in a shape sensor fiber with a graded index fiber micro-turnaround.

A critical limitation for optical fiber sensor technology is the complexity of the interrogators used in such measurements, which has driven continued interest in enhanced optical fibers and fiber assemblies that will simplify interrogator design. In this work, we report on a novel multicore fiber shape sensor utilizing a distal graded index (GRIN) fiber micro-turnaround. We show that four offset cores of this fiber can be interrogated simultaneously with a single high performance optical frequency domain reflectometry measurement. The GRIN turnaround is 498 µm in length and reflects signal from one offset core to an opposite core with a 2 dB roundtrip attenuation. We show that the bend sensing accuracy of our single measurement system is similar to the accuracy of sequential measurements of four individual cores. We also demonstrate fiber shape reconstruction with a single measurement over 0.55 m with 80 µm spatial resolution when the fiber is wrapped around two posts.

Research on Silicon-Substrate-Integrated Widely Tunable, Narrow Linewidth External Cavity Lasers

Widely tunable, narrow linewidth external cavity lasers on silicon substrates have many important applications, such as white-light interferometry, wavelength division multiplexing systems, coherent optical communication, and optical fiber sensor technology. Wide tuning range, high laser output power, single mode, stable spectral output, and high side-mode suppression ratio external cavity lasers have attracted much attention for their merits. In this paper, two main device-integrated structures for achieving widely tunable, narrow linewidth external cavity lasers on silicon substrates are reviewed and compared in detail, such as MRR-integrated structure and MRR-and-MZI-integrated structure of external cavity semiconductor lasers. Then, the chip-integrated structures are briefly introduced from the integration mode, such as monolithic integrated, heterogeneous integrated, and hybrid integrated. Results show that the silicon-substrate-integrated external cavity lasers are a potential way to realize a wide tuning range, high power, single mode, stable spectral output, and high side-mode suppression ratio laser output.

The analysis of pile-pile cap behavior under static loading test using distributed fiber optic sensor

Pile-Pile cap behavior was investigated in this study through the utilization of fiber optic sensors to continuously transmit information along the bored pile at a reading interval of 40 mm during each cycle of the static loading test. It is important to note that the fiber optic cables were installed on the two sides of the bored pile connected up to the pile cap to monitor the stress distribution beneath the pile cap while fiber optic sensors were installed under the pile cap. The ultimate axial bearing capacity expected to be achieved using the pile-pile cap configuration was 190 tons x 250% but failure occurred when the load used was increased to 190% of the design load. Therefore, the strain measurement obtained from the Distributed Fiber Optic Sensor Technology was analyzed to obtain information on the load transfer, pile shortening, mobilized unit skin friction, and mobilized end bearing at the pile-pile cap. The load portion carried out by pile cap was approximated at 6% to 23% from the actual top load applied. It was also discovered that the fiber optic sensors initially installed were able to record the strain caused to the soil by the load on the pile cap. The strain measurements on the soil made the zone of influence due to the loading of the foundation to reach two times the length of the pile while the biggest zone of influence lies at the end of the foundation. From recorded strain, show higher strain from one side compared to the other, this may indicate eccentricity of the load.

Application of Smart Fiber Optic Sensor Technology in Feature Extraction, Recognition, and Detection

To improve the signal recognition effect of the security system, this paper studies the security system based on intelligent Fiber Optic Sensor (FOS) technology. Firstly, the research background of intelligent FOS is introduced, and its current situation in feature extraction, recognition, and detection is introduced. Secondly, the double Mach–Zehnder (M-Z) Optical Fiber- (OF-) based interferometer model is implemented, and the Wavelet Analysis (WA) theory is introduced to analyze the characteristic threshold and Frequency (F) characteristics of intrusion signal. Finally, the distributed intelligent FOS-based perimeter security system is constructed, and an empirical study is conducted to verify its performance. The results show that the intruder knocking-induced signal F, intruder climbing-induced signal F, noiseless environment-induced signal F, and rainy environment-induced signal F are 0–250 kHz, 0–25 kHz, 0–1.5 kHz, and 0–3.5 kHz, respectively; in all the four cases, excellent results have been obtained after wavelet threshold denoising. Meanwhile, the received signal is decomposed into seven layers through multiscale WA theory. The signal feature classification is based on WA and takes variance as the representation, and the clear classification results are obtained; when the False Alarm Rate (FAR) = 1%, the detection probability of the proposed system is about 99%, while the detection probability of the traditional system is about 3%. The reference arm and sensing arm of the distributed OF-based perimeter security system can be laid in the same optical cable. Therefore, the designed wavelet threshold filtering method is feasible, and the detection probability of the designed WA-based system is higher than that of the traditional security system. The research content provides a reference for the development of intelligent FOS technology in the field of security.

Liquid Resin Infusion Process Validation through Fiber Optic Sensor Technology.

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.

Road Map of Fiber Optic Sensor Technology in China

Road Map of Fiber Optic Sensor Technology in China

Application of fiber optic measurement in textile‐reinforced concrete testing

AbstractIn research on concrete constructions, fiber optic sensor technology is becoming increasingly important. It enables high‐frequency and quasi‐continuous measurement of temperature and strain distribution. Furthermore, this technology offers the opportunity to determine the crack width within the cross section of specimens and not, as with conventional instrumentation, only from the outside. While experience for application of fiber sensors in steel‐reinforced concrete research already exists for several years, only few findings are available for textile‐reinforced concrete (TRC). This article gives a short overview of the principle of fiber optic sensor technology, presents possible concepts for utilization in TRC testing, and explains the necessary post‐processing steps for the preparation of the measurement results by means of an example from current research. Finally, the results are validated with conventional measuring methods and the applicability and further challenges are discussed.

Model Test Study on Deformation of Snowflake Shaped Steel Sheet Pile Based on OFDR.

As a newly developed pile foundation, the snowflake shaped steel sheet pile is composed of three Y-shaped sections with an included angle of 120° and has a large specific surface area, which can give full play to the side friction of pile and improve the bearing capacity of single pile. At the same time, the snowflake shaped steel sheet pile has a high strength, relatively few materials, and it has good prospects with engineering applications. In order to accurately grasp the mechanical characteristics of the snowflake shaped steel sheet pile, this paper carried out the model test of snowflake shaped steel sheet pile based on OFDR (optical frequency domain reflector) distributed optical fiber sensor technology. The results show that: (1) OFDR distributed optical fiber sensing technology can effectively monitor the strain of snowflake steel sheet pile; (2) under the vertical load, the strain of snowflake steel sheet pile decreases along the length of the pile; (3) the strain of the same section of snowflake steel sheet pile is different at different positions, the strain at the junction between web and web is basically the same as the junction between web and flange, and the strain of the pile shaft on the flange edge is larger.

Recent Advances in Machine Learning for Fiber Optic Sensor Applications

Over the last three decades, fiber optic sensors (FOS) have gained a lot of attention for their wide range of monitoring applications across many industries, including aerospace, defense, security, civil engineering, and energy. FOS technologies hold great promise to form the backbone for next‐generation intelligent sensing platforms that offer long‐distance, high‐accuracy, distributed measurement capabilities and multiparametric monitoring with resilience to harsh environmental conditions. The major limitations posed by FOS are 1) cross‐sensitivity, 2) enormous volume and large data generation, 3) low data processing speed, 4) degradation of signal‐to‐noise ratio over the fiber length, and 5) overall cost of sensor and interrogator systems. These challenges can be overcome by building advanced data analytics engines enabled by recent breakthroughs in machine learning (ML) and artificial intelligence (AI). This article presents a comprehensive review of recent studies that integrate ML and AI algorithms with FOS technologies. This review also highlights several FOS technology development directions that promise a significant impact on widespread use for several industrial applications, with an emphasis on energy systems monitoring. A perspective on future directions for further research development is also provided.

Deformation monitoring of ultra-deep foundation excavation using distributed fiber optic sensors

The development and utilization of urban underground space is producing a large number of deep foundation pits. On-site monitoring is a key issue to ensure the safety of the foundation excavation, especially the monitoring of the horizontal displacement of the structure. The rapid development of distributed fiber optic sensors technology in recent years could avoid the deficiencies of manual monitoring methods, which can quickly, real-time and continuously monitor the horizontal displacement of deep soils. At the same time, with the support of the information platform, the monitoring data can be transmitted back to the computer terminal to realize remote monitoring. This paper relies on the ultra-deep circular foundation excavation project (58.65m deep, the deepest foundation pit in Shanghai) in the test section of the Suzhou River deep tunnel, and uses the distributed optical fiber monitoring technology of Brillouin optical frequency domain analysis (BOFDA) to monitor the horizontal displacement of the deep foundation. This paper introduces the process, methods and precautions of optical fiber monitoring from early installation, equipment debugging to data acquisition, data processing and data analysis. The analysis results not only obtained the deformation law of ultra-deep foundation excavation, but also proved the advantages of optical fiber monitoring in deep foundation excavation. Finally, the data has been uploaded to the digital platform for remote monitoring in the future.

Optical Fiber Sensor for Heavy Chemical Detection: An Overview

Heavy metal contaminations such as mercury, lead, arsenic, cadmium, and zinc are becoming more serious and have become a hazard to human health. Due to their non-biodegradable nature, they can easily accumulate in the environment and cause toxicity even at low concentrations. Therefore, detecting the presence of these metal ions requires a highly sensitive sensing method. Traditional detection methods, such as electrochemical analysis, require complicated sample preparation, are costly, and typically require a lengthy measurement period. These days, optical fiber sensors have been acknowledged due to their unique characteristics such as compact size, high sensitivity, low cost, high flexibility, and immunity to electromagnetic interference. An overview of an optical fiber sensor technology for heavy chemical measurement is discussed in this paper. The sensing mechanisms are summarized, as well as the chemical water quality parameters and sensitivities.