Articles

about Fiber Bragg Gratings (FBG), FBG Sensors and Monitoring Systems

Fiber Bragg gratings in bogie frame

on April 6, 2020

wheelThe application of fiber optic technology as temperature and strain gauges is quite surprising in bogie frames. To be more precise, these fiber optic sensors are applied for examining the carbon fiber bogie, in addition to standard surface-mounted electrical-resistance fiber optic strain gauges.

Optical fibers of 125 micrometers in diameter or 250 micrometers with a coating layer are perfect for this aim. The thing is that the optical fiber is improved to produce fiber Bragg gratings (FBG) in the fiber, efficiently producing a number of semi-reflective mirrors over short but equal intervals.

The operating principle of the FBG system is based on the reflection of the signal (a small amount of the signal at each semi-reflective mirror) when the light is transmitted through a fiber Bragg grating. Herewith, “the originally reflected wavelengths (without the influence of strain) from each Bragg grating are compared to the reflected wavelengths when the structure is loaded.”

It should be noted that in the case of FBG deformation by strain, the spacing between the semi-reflective mirrors is either enlarged (tension) or decreased (compression). Therefore, the change combined with the efficient refractive index and the period of the fiber Bragg gratings leads to a shift in the reflected central Bragg wavelength.

The thing is that the wavelength size demonstrates the strain magnitude. Nevertheless, there is the same effect happened with temperature change, while the temperature effect is over 10 times the strain effect that is why the fiber optic technology needs to correct for temperature.

The researchers present the techniques applied to compensate for temperature where the fiber Bragg grating is placed close to the end-face of a cleaved optical fiber. The fact is the optical fiber with FBG is put in a capillary tube where one end is fused to the fiber, well away from the grating, and the opposite end is sealed. Finally, the FBG system responds only to temperature.

Nonetheless, it is not enough only to install several strain gauges into the bogie and link them to the instrumentation either. Ir is required to choose the proper fiber, for instance, bend-insensitive optical fibers are suitable. These are optical fibers where the diameter of the core includes 9.5-micrometer fibers with 4.5 mm long fiber Bragg gratings.

Additionally, it is necessary to properly install FBG systems to the bogie so as to act as a homogeneous part of the structure. Fiber Bragg gratings provide such benefits as efficient strain gauge transfer, capable to accommodate localized variations in the surface topology of the composite.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

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editorFiber Bragg gratings in bogie frame

Distributed temperature sensors promote warning systems

on March 30, 2020

smart-3871774_1280Temperature is a key safety indicator in any industry. The technology of distributed temperature sensors using optical fiber allows measuring the temperature at any point in the fiber, with an interval of 1 meter, resulting in the detailed temperature dependence of all required areas. The data obtained by this technique makes it possible to develop intelligent warning systems based on it, therefore, replacing outdated point-based monitoring systems.

The optical fiber itself acts like a fiber optic sensor, and the distributed nature of the DTS technology enables us to determine the temperature change at an arbitrary point, spreading many kilometers from it. Moreover, the measurement quality is not affected by electromagnetic radiation, thus, the distributed temperature technology is free from false alarms.

To be more precise, distributed temperature sensors (DTS) allow measuring the characteristics of an object along a fiber optic cable, while the fiber cable is a linear sensor, which is a continuously distributed sensing element throughout its entire length.

The operating principle is based on the reflectivity of stimulated Raman scattering of light (Raman effect). A semiconductor laser is also used to determine the location of temperature changes in a fiber optic cable. The fact is that the structure of the optical fiber changes when the temperature changes. 

When laser beam light from the laser system enters the area of temperature change, it interacts with the changed structure of the optical fiber and in addition to direct light scattering, reflected light appears.

The main advantages of fiber optic sensors in comparison with classical analogs are the following:

  • Compact size;
  • Very fast response to parameter changes in the environment;
  • Low weight;
  • Multiple parameters can be registered simultaneously by a single distributed sensor;
  • Reliability;
  • Very wide operating temperature range of DTS;
  • Small price per unit length of the sensing system;
  • High sensitivity;
  • Long operating time;
  • The high spatial resolution of temperature sensors;
  • Resistance to chemicals and aggressive environments;
  • DTS is not affected by electromagnetic disturbances;
  • The sensitive part of the fiber sensor does not require connection to power lines.

The processing unit measures the propagation speed and power of both direct and reflected light and determines where the temperature changes. For instance, at a wavelength of 1550 nm, a pulsed generation mode is used with a laser power limit of 10 mW.

There are several types of optical fibers, each of which meets certain requirements for its properties, depending on the application due to the fact that the properties of the optical fiber can be varied over a wide range. 

Physical effects on the optical fiber, such as pressure, deformation, temperature change, affect the properties of the fiber at the point of exposure and it is possible to measure the environmental parameters by measuring the change in the properties of the fiber at a given point.

In general, a fiber optic sensor consists of two concentric layers: fiber core and optical coating. The fiber optic light guide part can be protected by a layer of acrylate, plastic, reinforced sheath, etc., depending on the application of this fiber cable.

Thus, distributed fiber optic sensors are perfect for industries related to combustible and explosive materials, such as coal, oil and gas production, etc. for use in fire alarm systems of various structures.

alarm-3410065_640Application of distributed temperature sensors includes:

  • fire alarm systems in the road, rail or service tunnels;
  • thermal monitoring of power cables and overhead transmission lines to optimize production processes;
  • improving the efficiency of oil and gas wells;
  • ensuring the safe working condition of industrial induction melting furnaces;
  • monitoring the tightness of containers with liquefied natural gas on ships in unloading terminals;
  • detection of leaks in dams;
  • temperature control in chemical processes;
  • leak detection in pipelines.

In addition, DTS systems combined with other tools open completely new areas of application. For example, it is possible to design a specialized device – a fire detector based on a distributed fiber optic temperature sensor.

Detecting a fire in an industrial environment is not an easy task because of the large number of disturbing factors, many of which can be considered by detectors as carriers of fire signs. In addition, dust deposited on the DTS‘ sensitive elements makes it difficult to operate and it can disable them.

It is also necessary to take into account the possible smoldering of the deposited dust, which can also lead to false alarms. The presence of fumes and aerosols makes it impossible to operate smoke optical-electronic fire detectors. The presence of carbon monoxide will trigger gas fire detectors.

Industrial facilities and production are characterized by large volumes of premises, high ceilings, the presence of long tunnels, collectors, mines, inaccessible areas and premises with a complex configuration and geometry. And in these conditions, it is certainly possible to protect using traditional fire alarm systems, but this involves the use of a large number of detectors, and therefore they have high costs, including installation and maintenance of alarm systems and automation.

It is difficult to select detectors for explosive zones, especially for use in underground operations and mines. Aggressive media are often present in chemical industries. There are also objects of sea and river transport, characterized by the aggressive salt fog.

The use of non-electric sensing devices, the use of fiber optic cable allows the DTS to be applied in enterprises of the oil and gas complex, mines, underground operations, chemical industries (including those with aggressive environments), and metallurgy and energy enterprises.

As for oil companies, the active development of high-viscosity oil fields, which imposes strict requirements on the production equipment, and the severe depletion of most oil and gas fields require mining organizations to conduct prospecting and exploration operations, change production technologies and control the technical condition of wells.

The main task for mining companies to increase the well’s production capacity in real-time is to track information about the processes occurring in wells and fields. Solutions based on standard temperature sensors suggest well logging using point measuring instruments, which leads to the inaccuracy of the data obtained. 

The disadvantages of such sensing devices include the inability to fix the distribution of one of the most important parameters of the well – the temperature profile in real-time, as well as the need for power supply, the impact on the measurement results of external electromagnetic fields, labor and time costs required for the departure of the team and performing various operations, including the immersion of the fiber sensor element and its movement along the well, data processing, etc.

The fiber optic sensing system consists of distributed temperature sensors designed to measure temperature along the borehole, and point-to-point fiber pressure sensor. Optical fibers of a distributed temperature sensing system and pressure sensors can be structurally installed in a single fiber cable.

The fiber optic cable is resistant to mechanical damage. Additional fiber optic cable protection is not required during descent and lifting operations, but the protection of the fiber cable from mechanical damage during descent and lifting operations can be provided by the use of protective coatings.

If you want to obtain a highly efficient distributed temperature sensing system, you should choose the Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. 

Distributed temperature system provides continuous underground power lines monitoring of temperatures, detecting hot spots, delivering operational status, condition assessment, and power circuit rating data. This helps operators to optimize the transmission and distribution networks, and reduce the cost of operation and capital.

Usually, the DTS systems can detect the temperature to a spatial resolution of 1 m with precision to within ±1°C at a resolution of 0.01°C. Measurement distances of greater than 30 km can be monitored and some specialized systems can provide even tighter spatial resolutions.
The advantages of working with Optromix:

  • Our DTS system has the superior quality, however, its price is one of the lowest in the market;
  • Optromix is ready to develop DTS systems based on customer’s specifications.

If you are interested in DTS systems and want to learn more, please contact us at info@optromix.com

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editorDistributed temperature sensors promote warning systems

New concept of distributed fiber optic sensors

on March 23, 2020

illuminatedFiber optic technology promotes a new era of the Internet because optical fibers transmit huge amounts of data information all around the world. Herewith, fibers are regarded as an excellent platform for fiber optic sensors. It is possible to spread fiber sensors over hundreds of kilometers, simply install within structures, and even in a severe environment where the application of electricity is forbidden. Nevertheless,  optical fiber sensors have some inevitable problems as well.

The operating principle of an optical measurement is based on the light that touches the medium under test but conventional optical fibers are developed to perform the exact opposite. To be more precise, the design of optical fibers includes a glass cladding, with a much thinner, inner core. Herewith, the light is sent at the inner core, and every effort is made to keep light from leaking outside. “A substance under test, in most cases, lies outside the much larger cladding. Unfortunately, guided light does not touch upon much of the outside world.”

The only solution to the problem is coupling to the cladding modes that need for the inscription of permanent, periodic perturbations in the optical fiber medium (fiber Bragg gratings). FBGs are written at specific, discrete locations. Fiber optic sensor has limits to point-measurements only because their erasement or movement are prohibited. Optical fiber sensors are perfect in spatially-distributed analysis, in which every fiber optic segment operates as an independent measurement node. Additionally, it is possible to use two strong optical waves into the optical fiber instead as an alternative to the fiber Bragg gratings.

Also, there are Brillouin dynamic gratings, which can be switched on and off at will compared to standard FBGs. It is possible to short segments of arbitrary locations, and scan along the optical fiber. The thing is that the developed distributed fiber optic sensor is considered to be a first of its kind. Researchers have overcome some challenges: they succeeded to demonstrate the accurate measurement of refractive index outside the cladding boundary of traditional, unmodified optical fiber resulting in an 8cm spatial resolution. Herewith, the analysis demonstrates proper identification of short fiber optic sections immersed in water and ethanol, and clearly distinguished between the two. 

The researchers claim that it is a new concept of distributed fiber optic sensors. Such fiber sensors allow overcoming a decades-long challenge: fiber optic sensors perform the distributed mapping of refractive index outside the cladding of conventional optical fiber, where light does not achieve. The applications of distributed fiber optic sensors include leak detection in critical infrastructure, and process monitoring in the petrochemical industry, desalination plants, food and beverage production and more.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

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editorNew concept of distributed fiber optic sensors

FBG sensors prevent tunnel fire

on March 16, 2020

railway-tunnel-4427611_640Tunnel fires are not regarded as usual, however, they also can perform great damage to lives and properties if they take place. The process of fire detection inside the lengthy and curved tunnel is challenging. Nevertheless, fiber optic sensors based on fiber Bragg grating or FBG technology allows detecting tunnel fires and FBG sensors are considered to be a novel methodology that determines not only the presence but also locates the fire inside the tunnel.

To be more precise, FBG sensors are installed across the inner sides of the tunnel where they control it by the optical spectrum analyzer or wavelength division multiplexing sensor interrogator at the exit. “The change in the center wavelength from the original spectrum at the output denotes the temperature change (fire occurrence) inside the tunnel.” FBG fiber optic sensors offer output with more precision, herewith, fiber Bragg gratings can hold very high-temperature values.

It should be noted that it is possible to detect fires applying various ways, for instance, installing temperature sensors inside the tunnel or controlling the tunnel through the camera. Temperature sensors enable to sense of tunnel fires but their location presents difficulties. Moreover, such a temperature sensor as a thermistor can not stand very high temperatures (1000˚C) as well as there is a problem of self-healing.

FBG sensors, in their turn, provide a highly efficient process of sensing and locating. The thing is that fiber Bragg gratings in fiber optic sensors lead to a narrow range of wavelengths to shift and the rest of it to transmit through it. The center of the reflected wavelength is Bragg’s Wavelength. The features of FBG sensors allow measuring temperature or strain changes in the structures. Additionally, FBG fiber optic sensors have a greater temperature steadiness ability, more immune to electromagnetic interferences, longer lifetime, explosion safe and it is possible to be multiplexed.

Fiber Bragg grating is a short part of optical fibers that reflects a specific light wavelength and transmits all other wavelengths. FBGs operate as an optical notch filter. The operating principle is based on the Bragg grating patterns inside the fiber that perform the reflection. The design of fiber Bragg gratings includes holographic interference or a phase mask to undergo a short length of optical fiber to a periodic distribution of light intensity. 

The developed FBG sensors have been already tested and demonstrated the following results: the sensitivity value of the fiber optic sensor achieves 20 pm/˚C. Also, it is possible to increase the accuracy of fire location inside the tunnel by increasing the number of FBG fiber optic sensors for the considered tunnel length of 4 km. Thus, FBG technology can help to perform operations very fast and can save many lives and properties.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

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editorFBG sensors prevent tunnel fire

Totally new application of DAS systems

on March 2, 2020

date-palm-223250_640The red palm weevil is regarded as a serious problem for the cultivation of date palms leading to massive economic losses worldwide. Although curative techniques are not challenging, early detection is still difficult to be performed. Fiber optic technology allows overcoming the threat and offers reliable detection of RPW by a distributed acoustic sensor (DAS).

Modern DAS systems enable to detect feeding sound created by larvae as young as 12 days, in an infected tree. Compared to traditional methods, the DAS technique provides a cost-effective and non-invasive alternative that can perform 24-7, real-time monitoring of 1,000 palm trees or even more. Moreover, distributed sensors allow controlling temperature, a crucial characteristic to monitor farm fires, one more important problem for the cultivation of palm trees around the world.

Nowadays there are various techniques to detect the weevils. For example, it is possible to use trained dogs to smell the odor, however, such sensing is not precise and has low efficiency. That is why distributed acoustic sensors are considered to be the most promising early detection techniques. Current sensing technologies use sound probes to install them right into the tree trunk but such acoustic sensors damage plants and create a nest for other insects.

The novel distributed acoustic sensor combined with a signal processing algorithm offer a reliable solution for the early detection of red palm weevils. The design of the DAS system is based on the use of the laser and photodetector installed within a single unit, while only the optical fiber is wound around the palm trees to create an optical network. The developed DAS technique has been already tested on two palm trees (one healthy and one infested with ~12 days old larvae.).

The thing is that the novel distributed acoustic sensors are “uniquely non-invasive, providing 24-7 monitoring, at relatively low cost, and offering wide coverage of the farming area, using only a single fiber optic cable.”

To be more precise, all the optical/electronic components applied to design acoustic sensors are put into a sensing unit, which is linked to an optical fiber that is extended throughout the palm-trees farm. Herewith, the fiber circles each tree trunk, from the ground up to a ~1 m height because the probability of RPW is extremely high there. Also, the fiber optic cable between trees can be either put on the ground buried in the soil providing real-time monitoring that promotes precise identification of locations of the infected and healthy trees.

The design of DAS systems includes the use of phase-sensitive optical time-domain reflectometry (Φ-OTDR) that has numerous potential applications in the oil and gas industries as well as for real-time structural health monitoring. The operating principle of distributed acoustic sensors is based on “launching a train of optical pulses generated by a narrow linewidth laser into a single-mode fiber.”

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring of commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

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editorTotally new application of DAS systems

The noise of Distributed Acoustic Sensing is suppressed

on February 17, 2020

ear-2972890_640A technique of noise suppression used f-x deconvolution and the wavelet transform allows reducing jump edges in the phase noise of distributed acoustic sensing. The DAS system has been already tested and demonstrated great results of high performance in terms of increasing the quality level of seismic waves. Distributed acoustic sensing provides relatively stable phase sensitivity as well as better the signal-to-noise ratio, leading to more remarkable features of seismic wave signals.

To be more precise, distributed fiber optic sensing based on Rayleigh scattering is not new and used in various applications to control current assets and employ new resources. It is possible to apply such DAS systems to provide efficient and comparatively inexpensive development of perimeter security systems and produce defensive redundancy.

Different methods have been used to apply Rayleigh scattering in the development of distributed fiber optic sensors. For instance, a distributed sensing technology of optical time-domain reflectometry (OTDR) was used for the first time over three decades ago. Nowadays a noise suppression technique based on f-x deconvolution and the wavelet transform is considered to be the most efficient for distributed acoustic sensors.

The thing is that f-x deconvolution is regarded as a traditional technique of seismic data processing. The application includes the treatment of seismic signals by fiber optic sensors as a two-dimensional (2D) image in terms of time and channel. The DAS system enables us to extract the signal characteristics of each channel with a comparatively stable noise distribution between channels. 

Usually, such techniques as deconvolution or the wavelet transform are applied separately in traditional seismic noise processing but here these techniques are combined in distributed sensing technology to minimize the number of wavelet transform layers and reach effective low-frequency noise suppression. The DAS system offers such benefits as comparatively stable phase sensitivity over the whole sensing range, the reduction of jump edges in phase noise, and more evident features of seismic wave signals.

The operating principle of distributed acoustic sensing used f-x deconvolution is based on “the assumption that desired signals are continuous and predictable whereas random noise is incoherent and unpredictable.” DAS sensors are actively used for oil and gas exploration. Thus, the noise compression technique improves the phase noise performance of the DAS system. Moreover, the jump edges from the noise of fiber optic sensors are reduced with the same peaks and valleys compared to the original signals which play a crucial role in calculating the time delay of peaks and valleys between various channels. 

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring of commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

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editorThe noise of Distributed Acoustic Sensing is suppressed

Extremely precise FBG sensors promote smaller chips

on February 10, 2020

electricAn electrical engineer from the Netherlands has developed a fiber optic sensor based on fiber Bragg grating technology (FBG)with a super-precision of less than the size of an atom. Such FBG sensors favor the production of smaller chips, which in turn are required to develop faster computers.

The developed fiber sensor allows measuring deformations less than the width of an atom is possible to be measured. Thus, these fiber optic sensors offer a highly promising application that enables to improve the accuracy of current machines. It should be noted that even the slightest deformation of the wafers in machines may result in serious problems.

“These wafers are actually quite stiff, but because they are moved about at such great speed, they are subject to g-forces that slightly deform them. Measuring this deformation by FBG sensors gives the opportunity to compensate for it in some or other way, and opens up the possibility of producing even smaller chips.”

This is the main reason why the engineer began developing a fiber sensor based on FBG technology, enabling sensing these deformations of roughly one nanometer per meter. The operating principle of this extremely precise FBG sensor is that it is possible to measure the deviations in the frequency of laser beam light with high precision, as well as the principle used by fiber Bragg grating – an optical fiber of sorts treated in such a way that it becomes opaque for a very specific color of light.

Herewith, such a resonance frequency is dependant on the extent to which the optical fiber is stretched. Therefore, fiber Bragg gratings can be employed here to the moving parts as a way to measure the wafer’s deformation. The fiber optic sensing system based on FBG technology has been already tested in the lab. Although modern machines require dozens of such fiber sensors, it is not a challenge because FBG sensors are not expensive and light-weight.

The engineer claims that it succeeded in achieving the accuracy of 5 nanometers per meter, thus, the fiber optic sensor of a few centimeters in length allows measuring the deformation of a couple of dozen picometers, herein, that is less than the diameter of an atom. Nevertheless, several challenges have to be overcome before this incredible level of precision could be reached due to fiber Bragg gratings.

The first challenge is a need for sophisticated stabilization techniques to provide that the laser beam light has the right frequency. However, the main problem is considered to be the resonance frequency of the FBG sensor that depends on not only the deformation but also the temperature. 

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

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editorExtremely precise FBG sensors promote smaller chips

Fiber optic seismic sensors from submarine cables

on February 3, 2020

A team of researchers from France proposes for the first time the opportunity to detect the propagation of seismic dmitry-bayer-GH8fTXN1P5k-unsplash (1)waves on the seafloor by fiber optic seismic sensors made from submarine telecommunications cables. The researchers confirm that the potential application of such seismic sensors includes the use of existing infrastructure for the detection of earthquakes, as well as swell and underwater noise.

It should be noted that about 1.2 million kilometers of telecommunications cables cut across the ocean floor that is equal to three times the distance from the Earth to the Moon. The cables consist of optical fibers leading to simple communication by phones, SMS or e-mail. Herewith, the optical fibers could soon find a new application, that of detecting acoustic and seismic waves.

To be more precise, the researchers apply a 41 km-long fiber cable installed at the coast of Toulon in southern France for their tests to obtain data from the fiber optic sensors of the underwater observatory that is at a depth of 2500 m. Moreover, a special technique based on small impurities in the optical fibers is used for sending light back to the transmitter.

The thing is that “by stretching or contracting the optical fiber, the passage of a seismic or acoustic wave alters the distance between these impurities, and thus the backscattered signal, by a tiny amount.” Nonetheless, the researchers have to prove the opportunity to detect these differences in submarine fiber optic cables because of the insulating layers that surround the optical fibers.

Thus, the pulses of light put at the optical fiber and allow analyzing the backscattered signal. The researchers use the 41 km of optical fibers for tests and change them into more than 6000 fiber optic seismic sensors. Moreover, such fiber sensors enabled to detect a magnitude 1.9 earthquake that happened during the test at each of the sensing areas with a sensitivity close to that of a coastal seismic station, even despite the fact that it was located over 100 km from the fiber optic cable.

Nevertheless, the benefits of seismic sensors do not complete: the sensing points of fiber cable are highly sensitive to waves that go through the ocean, for instance, those created by the swell. The influence of waves on the seafloor near the coast, as well as the effect on the abyssal plain, where they produce “seismic background noise” was captured.

Finally, the fiber optic seismic sensors make it real to find out for the first time how thee tiny vibrations that permanently interact with the Earth’s interior are created, allowing specialists in geophysics to examine its structure. Also, such fiber sensors may overcome a wide range of scientific and societal challenges like earthquakes, coastal erosion, the interaction between life, the oceans and the solid Earth, etc.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

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editorFiber optic seismic sensors from submarine cables

Distributed fiber optic sensing applies an entangled quantum network

on January 27, 2020

Quantum_NetworkQuantum-enhanced metrology is regarded as a popular area of research for years because of its promising applications, varying from atomic clocks to biological imaging. According to the researches, a non-standard distributed sensing system offers significant advantages compared to traditional fiber optic systems.

These researches help a team of scientists from Denmark to carry out an experiment on distributed fiber optic sensing and the benefits of employing an entangled quantum network to detect an averaged phase shift among numerous distributed sensing nodes. The fiber optic sensing technology uses several methods that enable collecting more accurate measurements in different areas.

The purpose of the new study is based on squeezed light and homodyne detection that is now established distributed fiber optic sensing techniques. The team aims at “measurement of a global property of numerous spatially separated objects and investigate whether probing these objects simultaneously with entangled light led to more accurate results than probing them individually”. 

Thus, the application of a quantum network to probe the objects simultaneously allows distributed sensing systems with far higher accuracy than that attainable when examining probes individually. To be more precise, the team measures the phase shifts (set with wave plates to a known value) by the fiber optic system that sends a weak laser beam through and detects the change in the light’s phase quadrature with homodyne detectors.

The benefit of applying distributed fiber optic sensing plays a really important role when it is necessary to measure the property of numerous objects connected in an optical network. Nevertheless, the losses in the network and detectors are required to be kept low in order to successfully raise the accuracy, alternatively, the quantum benefit of distributed sensing disappears.

The researchers succeeded in the experimental demonstration of the benefits connected with employing multi-mode entanglement for distributed fiber optic sensing. The thing is that the benefits have been previously predicted, however, only highly idealized scenarios and experimentally very difficult probe states or detection methods were taken into consideration. The developed fiber optic system demonstrates that these benefits are available even with current noisy sensing technology.

The fiber optic system finds potential applications in various areas of research and technology development. For instance, they provide a high sensitivity of molecular tracking devices, atomic clocks, and optical magnetometry methods. Moreover, the distributed fiber optic sensing gives valuable information about how quantum-enhanced metrology can be reached utilizing readily accessible technologies, for example, squeezed light generation and homodyne detection.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

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editorDistributed fiber optic sensing applies an entangled quantum network

Distributed sensors for structural health monitoring of bridges and dams

on January 20, 2020

damsNowadays distributed fiber optic sensors remain a subject of great interest for constant structural health monitoring of huge structures, for instance, bridges or dams. Herewith, the more sensing points there are, the more effective monitoring the sensing system offers. Thus, newly improved distributed sensors with 1 million sensing points provide prominently faster detection of structural problems that are now accessible.

Fiber optic sensors allow accurately detecting erosion or cracking before a dam fails. Therefore, earlier detection of a problem by fiber optic sensing systems may lead to its possible prevention from later deformation or provision of sufficient time for evacuation procedures. Fiber sensors are considered to be perfect for controlling infrastructure since they suit for use in harsh environmental conditions and in areas that lack nearby power supply.

The operating principle of distributed sensors is based on “changes in the structure at any of the sensing points along the optical fiber that cause detectable changes in the light traveling down the fiber”. Despite the high popularity of distributed fiber optic sensors, the main applications of sensors include the detection of leaks in oil pipes and structural health monitoring for landslides along railroads.

It should be noted that the novel fiber optic sensing system enables tracing train and temperature changes from 1 million sensing points over a 10-kilometer optical fiber in less than 20 minutes, while strain parameter demonstrates deformation or mechanical stress on an object of interest. Herewith, the new distributed sensor is regarded as to be about 4.5 times faster than previous fiber sensors with 1 million sensing points. A larger number of sensing points require fewer optical fiber units for structural health monitoring of an entire structure resulting in cost reduction.

A large density of sensing points makes distributed fiber optic sensors suitable for such applications as avionics and aerospace, where every inch of a plane wing has to be controlled properly. According to researchers, the conventional technique of generating the continuous signal in fiber sensors undertakes distortions in the fiber optic system at higher laser powers. This problem has been solved by using the approach known as Brillouin optical time-domain analysis.

The fiber optic sensor has been already tested and showed the opportunity to measure the temperature of a hot spot to within 3 degrees Celsius from the end of a 10-kilometer long optical fiber. Additionally, it is planned to improve the distributed sensor and make it even faster resulting in the further reduction of the acquisition time. Future enlargement of sensing point density will promote the fiber sensors being used in new fields, for example, biomedical applications.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

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editorDistributed sensors for structural health monitoring of bridges and dams