Tag: FBGs

The development of fiber Bragg gratings using highly doped aluminosilicate glass optical fibers

The continuous development of high-temperature fiber Bragg grating technology (FBG technology) promotes a significant increase in novel applications. For instance, nowadays FBG applications include such fields as “the temperature profiling of high-temperature manufacturing equipment, monitoring of fuel combustion machinery, temperature regulation of large diesel engines in trains, as well as assessment the structural integrity of a building post-fire”.

Additionally, high-temperature FBG technology is used in oil and gas industries where the resistance to the temperatures higher than 500 °C is totally recommended. To be more precise, the sensors based on fiber Bragg gratings are able to stand temperature conditions below and above 800 °C. Herewith, the thermal stability of FBG sensors depends closely on the intrinsic thermal stability of the core-cladding materials.

This is the reason why the development of fiber optic technology with higher thermal resistance, for example, the molten core technique, is still required. Thus, it was decided to apply a circular core/cladding glass optical fiber containing a yttrium-doped aluminosilicate core and a silica cladding in FBG sensors that may withstand about 900 °C.

The following types of FBG sensors are based on the nature of refractive index modifications induced by laser irradiation. The following types of FBGs are distinguished:

The type I in fiber Bragg gratings produces a laser irradiation regime that emits an isotropic increase of the refractive index.
The type II in FBGs, in its turn, has a connection with the creation of an anisotropic index change upon irradiation, generally emitted by the presence of nanogratings, and leads to the observation of form birefringence.
Ultra-high temperature regenerated fiber Bragg gratings are able to operate above 800 °C in silica optical fibers. Therefore, these FBGs find their application in such areas as the profiling of high-temperature manufacturing equipment, dual pressure/temperature sensing for gas turbines, sodium-cooled nuclear reactors, high-temperature air flow meters for internal combustion engines and train engine temperature regulation.
Femtosecond fiber Bragg gratings are made by ultrafast laser systems usually in the NIR spectral range, resulting in their use as temperature sensors for monitoring fluidized bed combustors, as well as for radiation-resistant temperature sensors.
Sapphire fiber Bragg gratings allow achieving even higher temperature operation by using materials with higher melting points.

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

Low-cost FBG interrogator for dynamic measurements

Fiber Bragg grating technology (FBG technology) offers fiber optic sensors that allow carrying out the measurement of such parameters like temperature and/or mechanical strain. However, the high cost of fiber sensing systems is considered to be a major disadvantage for commercial applications.

It should be noted that the popularity and fast growth of fiber optic technology for sensing applications promote numerous research in various areas, for example, industry, medicine, aerospace, civil applications where such physical and chemicals factors as acceleration, level, temperature, strain, pressure, deformation, refractive index play a very important role.

Optical fiber sensors are perfect for use in the mentioned measurements. Fiber optic technology offers numerous benefits that include “intrinsic safety, resistance to chemical corrosion, immunity to electromagnetic interference, electric isolation, compact size, lightweight sensing heads, high resolution, easy multiplexing, and capability for extremely remote monitoring without the need of electrical power at the measuring point”.

Moreover, fiber Bragg gratings are the most used technology for the measurement of temperature and/or mechanical strain parameters among other optical fiber sensors. To be more precise, the term “fiber Bragg gratings defines as nanometer periodical refractive index changes engraved in an optical ﬁber core.”

The principle of FBG technology operation is based on the injection of a broadband light spectrum in the optical fiber. Herewith, there is a concentration of the reflected spectrum at the fiber Bragg grating wavelength, herewith, it is possible to see a suppression in the transmitted signal at the same wavelength.

Additionally, the same operation principle of the FBG technology is used in new and more complex structures, for example, planar FBG sensors. Thus, the FBGs offer very precise measurements due to the wavelength that is considered to be a permanent feature of the signal along the optical fibers.

Nevertheless, the FBG interrogators have some challenges in large commercial applications because of their high cost. That is why the development of new, low-cost alternatives to the current FBG interrogators is highly required. Therefore, there are several solutions to the present problem.

One of the solutions is the use of frequency-to-amplitude conversion (a fast and low-cost FBG interrogation technology), in which the spectral variations of fiber Bragg gratings are straightforwardly transmitted into optical power variations. Herewith, the presented FBG technology is based on the twist between both the FBG sensors and the edge filter spectra.

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Fiber Bragg gratings make semiconductor lasers more stable

Researchers from the Czech Republic demonstrate a new technique that allows improving wavelength stability and tunability of semiconductor laser diodes in fiber laser interferometers due to fiber Bragg gratings (FBGs) technology. This simulation technique makes the calculation of arbitrary fiber Bragg grating (apodized, chirp, etc.) with a high level of accuracy by a combination of techniques based on layered dielectric media (LDM) and transfer matrix technology.

Thus, based on the simulations and measurements made by the commercially available FBG technology, it has succeeded in the development of a special 100 mm long fiber Bragg grating with apodization. Herewith, the researchers confirm that the new FBG technology of improved linewidth and mode-hop free tuning range of semiconductor laser systems at the wavelength 760 nm enables to increase the resolution of a laser interferometer. Therefore, the absolute fiber laser interferometer with Vertical Cavity Surface Emitting Laser (VCSEL) to easily apply the FBG system to make the wavelength parameter more stable and monitor the tuning range was produced.

Typically, two types of fiber Bragg gratings are distinguished in the used technology: FBG with a period of ~0.5 µm, and Long-Period Fiber Bragg Gratings (LPFGs) with a period from 100 to 500 µm. Additionally, it should be mentioned that their production requires different methods. Thus, the creation of fiber Bragg gratings is performing by interference patterns, while long-period FBGs are produced by side irradiation of the fiber optic components through an amplitude mask or using the fiber translating technique.

Therefore, the application of FBGs offers high thermal stability, retaining optical properties up to 500 °C. Moreover, the production technique has a dependence on such parameters as the length, the type, and the other factors of the FBG technology. It is possible to determine the necessary parameters on the basis of the FBG spectral profile.

Finally, the simulation technique based on the application of fiber Bragg gratings was developed and tested several types of FBGs. For example, chirped and apodized fiber Bragg gratings (FBGs with modulation of the amplitude and with modulation of the spacing). Herewith, this new FBG system provides numerous benefits in comparison to other types of FBGs.

The main benefit is suppressing the side lobes in the fiber Bragg grating spectral properties. The developed FBG system is a compact reliable one that ensures the operation in an industrial environment where the majority of optical components would be fiber-optic.

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FBG sensors in Biomechanics and Rehabilitation Application

Nowadays the technology of fiber Bragg gratings is considered to be quite attractive for sensing applications in biomechanics and rehabilitation engineering fields thanks to the proposed FBG benefits such as compact size, lightweight, biocompatibility, chemical inertness, multiplexing capability, and immunity to electromagnetic interference.

Additionally, FBG technology overcomes other traditional technologies for the measurement of a range of physical parameters or for the performance of high-sensitivity biochemical analysis because fiber Bragg gratings offer a high-performance alternative to conventional sensing devices.

It should be noted that the sensing application of FBG sensors includes such areas as aeronautics, automotive, civil engineering structure monitoring, and undersea oil exploration. Nevertheless, the use of FBG sensors in biomechanics and rehabilitation is quite novel and it still requires its practicality for full-scale implementation.

The potential application of FBG technology may include the following fields: strain detection in bones, “pressure mapping in orthopedic joints, stresses in intervertebral discs, chest wall deformation, pressure distribution in Human Machine Interfaces (HMIs), forces induced by tendons and ligaments, angles between body segments during gait, and many others in dental biomechanics”.

FBG sensors demonstrate great potential for biomechanics and rehabilitation engineering thanks to their benefits, thus, making FBG technology suitable for a human body. To be more precise, fiber sensors are able to adapt to the body, so it is possible to employ them for in vivo measurement and to left for long-term monitoring.

Moreover, fiber Bragg gratings can change traditional sensing technologies such as electrical strain gauge (ESG), piezoelectric, resistive, or another solid-state sensing, both for measuring physical characteristics or for carrying out high-sensitivity biochemical analysis. The development of FBG continues, and it is possible that very soon new FBG sensors with improved characteristics appear.

If you want to obtain a highly efficient 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. The company provides a wide range of sensors: temperature sensors, strain sensors, displacement sensors, tiltmeters, accelerometers. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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Space application of FBG sensors

Fiber Bragg grating sensors are highly useful fiber optic sensing devices that help carry out the monitoring of temperature and strain characteristics even during a nanosatellite mission. FBG sensors present highly attractive reliable fiber optic solutions for process monitoring in a spacecraft. Additionally, it is possible to install these fiber sensors in composite structures or attached on their surface for structural health monitoring during the entire life cycle of a satellite.

To be more precise, space application of fiber optic sensors requires the use of two fiber Bragg gratings to measure temperature and strain characteristics during one space mission. The main aim of the mission is the validation and demonstration of the suitability and reliability of fiber optic technologies when it comes to a small area with numerous restrictions in terms of mass and power consumption.

Despite the fact that FBG sensors offer great performance in various fields of application, especially in industry, engineering and science, however, the use of fiber sensors in space application is not so popular, although fiber optics are presented more than 30 years in space but typically applied to transmit data or to guide the light for illumination purposes.

Fiber sensors based on fiber Bragg grating technology have numerous benefits such as electromagnetic immunity, the possibility of multiplexing, and weight-saving by taking copper harness away. This is the reason why fiber sensing technology is perfect for the harsh space environment.

Also, FBG sensors are better than other optical fiber sensors because their optical response does not depend on the optical power of the light source the eventual loss of energy transmitted along with the optical fiber, and of the response of the photodetector, thus, the response of the fiber sensor is considered to be wavelength-coded.

The used FBG technology has been successfully tested and the tests presented the capability and reliability of fiber optic sensors based on fiber Bragg gratings in space environmental conditions. In spite of the high restrictions in terms of mass, volume, and power consumption, FBG sensors offer an optimal performance of all-optical fiber components after their 3 years’ application in the space environment.

Finally, during the whole space mission crucial attenuation proving the degradation of fiber optic components because of harsh environmental conditions (as well as radiation and vacuum conditions) has not been registered. Herewith, the used tunable laser system for telecommunications purposes also presented excellent results in the space environment. It is possible that these FBG sensors contribute to the creation of more complex sensor arrays with a more complex FBG interrogator unit that will enable better resolution and operation in a wider temperature range.

If you want to obtain a highly efficient 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. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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FBG accelerometers measure acceleration and vibration on trains

Nowadays train accidents often cause severe injuries and even cases of death. Nevertheless, researchers from China have designed new fiber optic sensors that allow measuring acceleration and vibration characteristics on trains. Additionally, this optical fiber technology can be used in a combination with artificial intelligence in order to prevent potential railway accidents and catastrophic train derailments.

To be more precise, the FBG accelerometers are able to monitor problems in the railway track or the train in real-time to detect defects before an accident happens. Such fiber optic devices identify frequencies more than double that of conventional optical fiber accelerometers, making them ideal for monitoring wheel-rail interactions.

The principle of durable FBG sensors’ operation is based on the use of no moving parts, herein, the fiber accelerometers demonstrate good operation in the noisy as well as in high-voltage environmental conditions found in the railway field of application. Moreover, the researchers confirm that their novel FBG accelerometers can be applied in other vibration monitoring applications. For example, fiber optic applications include structural health monitoring for buildings and bridges and vibration measurements of aircraft wings.

It should be noted that the researchers have been developing condition-monitoring optical fiber systems for more than 15 years using an all-optical sensing network to continuously monitor crucial railway components. It is planned that these fiber optic sensing systems help change poor efficient traditional railway maintenance routines by predictive maintenance based on actual conditions.

The developed FBG accelerometers demonstrate the following benefits that include:

immunity to electromagnetic interference;
long transmission distance;
no need for electricity.

But a need for FBG sensors for the measurement of various characteristics in railway systems still remain. Traditionally, fiber accelerometers are based on fiber Bragg gratings whose use is limited by 500 Hz vibrations. Therefore, such fiber optic technology was not suitable for the measurement of the wheel-rail interactions that are considered to be an important source of track wear.

Finally, the researchers have developed totally new FBG accelerometer based on a specific optical fiber (a polarization-maintaining photonic crystal fiber). It has been tested by installing the optical fiber device on an in-service train. Thus, the FBG accelerometer demonstrates a similar operation to the piezoelectric accelerometer, but it does not require expensive shielded fiber cables to take the effects of electromagnetic interference down.

If you want to obtain a highly efficient 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. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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Fiber optic inclinometer demonstrates the versatility of FBG sensors

Fiber optic inclinometer is considered to be one of the most important optical fiber devices used in numerous fields of application. For example, in geophysical engineering, the inclinometer based on the fiber Bragg grating technology (FBG) allows monitoring the angle of inclination at regular intervals along the borehole to profile the land displacement.

Current fiber optic inclinometers utilizing FBG sensors demonstrate a high level of sensitivity and angle of measurement resolution of 0.006°. It should be noted that traditional inclinometers have disadvantages when it comes to their involuntary twist during the process of installation. And optical fiber sensors were widely thought to overcome these limitations due to the absence of moving parts.

Nevertheless, the combination of traditional inclinometers with FBG technology enables us to resolve the challenge and make the fiber optic inclinometers’ operation independent of twisting, therefore, the precision remains constant. Moreover, despite numerous fiber optic techniques that measure temperature, strain, pressure, and other parameters, new fiber optic inclinometer based on a fiber’s taper and a long-period fiber Bragg grating have been recently developed.

The principle of the fiber optic device is based on the use of conventional fiber Mach-Zehnder interferometer that allows dividing the incoming light between two optical fibers and recombining it at a second junction. To be precise, in a Mach-Zehnder system, a long-period fiber Bragg grating dissipates light at its resonant wavelength from the optical fiber core into the cladding, while a second-long period FBG takes light from the cladding back into the fiber core.

The novel fiber optic inclinometer is a simpler device that includes only a single long-period fiber Bragg grating. Moreover, it uses the taper that enables to increase the core field so that part of its light is coupled into the cladding. The fiber optic inclinometer offers the following advantages in its operation:

the immunity to electromagnetic interference;
the high sensitivity;
the compact size;
the multiplexing and remote interrogation abilities.

This optical fiber device based on the interferometer was tested in the measurement of angular displacement. During the experiment, the optical fiber on either side of the taper was sheathed in capillary tubes and then twisted accurately at the taper. Thus, such a bend influences the fringe visibility, but not the location of the fringes.

Optromix is a FBG sensor manufacturer that provides top of the line FBG sensing systems suitable for monitoring of the constructions’ inclination. If you have any questions or would like to buy a FBG product, please contact us at info@optromix.com

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The use of fiber optic sensing solutions on active warships

The researchers from NASA Armstrong Flight Research Center form a partnership with members of the Naval Surface Warfare Center to create fleet maintenance capabilities with the help of new fiber optic sensing systems. Thus, the development of novel highly promising fiber optic sensing solutions becomes possible.

The thing is that fiber optic technology is considered to be one of the most essential and promising techniques, and the cooperation of the mentioned above organizations may help to find the solution to all current challenges. Herewith, there was a project of Remote Environmental and Condition Monitoring Systems that could be restarted again with the help of new possibilities of optical fiber technology offered by companies.

The main function of fiber optic sensing systems is the record of every parameter. For example, today fiber optic sensors are applied for monitoring temperature, relative humidity, shock, and vibration. Future fiber optic applications include the monitoring of hypergolic propellant fuels, liquid detection, contamination, radiation, strain, and electric and magnetic fields.

Fiber optic sensing solutions allow fulfilling a need to control high valued assets applying fiber optic sensing technology that can be installed with live ordnance. Moreover, the fiber optic sensing system was tested on a self-defense test ship before its installation on real warships.

Such fiber optic technology enables us to increase confidence in real-time fiber optic applications on active warships and ensure sensing systems are ready before future improvements. This optical fiber sensing system contains as many fiber optic sensors as possible to develop a new project that allows demonstrating and detecting main challenges in a relatively short time.

The Office of Naval Research offers fiber optic sensing solutions that are able to monitor, identify, and forecast the health of most critical components, hot spots, fatigue, and damage-prone parts of weapon systems in a reliable and economical way.

Such fiber optic technology may enhance sensing systems while cutting the maintenance cost, current parts life, and new materials. The advantages of fiber optic sensing solutions are based on the application of lightweight, compact fiber optic sensors compared to traditional big, heavy, and hard resisting gages.

Finally, the researchers from NASA developed fiber Bragg Grating or FBG (a fiber optic sensor that reflects certain wavelength and sends all others), as well as two techniques they apply in their fiber optic sensing systems: conventional Wavelength Division Multiplexing and unique FBG Interrogation Technology called the Optical Frequency Domain Reflectometry.

If you want to obtain a highly efficient 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. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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FBG pressure sensors for pipeline leakage detection

The technology of fiber Bragg grating or FBG is widely used in numerous sensing technology fields of application. For example, today FBG pressure sensors are installed to detect the leakage process of prestressed concrete cylinder pipe. This type of pressure sensor is based on the use of a Bourdon tube with two fiber Bragg gratings attached on its outside and inside surfaces.

Such a wider sensing application is caused by an increasingly large number of attractive characteristics of FBG sensors that include intrinsic safety, immunity to electromagnetic fields, remote sensing, and large multiplexing capabilities. Therefore, the pressure parameter remains the most important physical factor in the process industry.

Nevertheless, conventional pressure sensors based on electrical train gauge, vibration wire, mechanics have several disadvantages that include the absence of the ability to withstand harsh environmental conditions with critical electromagnetic interference, adventurous chemicals, or explosion matters. Moreover, such sensing systems do not allow making pressure’s multipoint measurement and online monitoring at a long distance.

It should be noted that the intrinsic pressure sensitivity of an FBG sensor is considered to be about 3.04 pm/MPa, which is quite a low index for the practical pressure measurement. Despite numerous ways proposed to increase the sensitivity factor of FBG pressure sensors, such as the installation of FBG in polymer, soldering metal-coated FBGs on a free elastic cylinder, and embedding the FBG fiber to a diaphragm, all these techniques propose relatively complex structures which are difficult to produce.

The thing is that the prestressed concrete cylinder pipe is widely used for water transportation in different areas, for example, municipal, industrial, and plant piping systems. Thus, the role of FBG pressure sensors for security monitoring and reliability management of huge cylinder pipes remains very important because now the sensing technology still faces numerous challenges.

Nevertheless, the use of a Bourdon tube in FBG pressure sensors as the spring element allows detecting spring elements. Herewith, the measurement sensitivity increases and becomes 1.414 pm/kPa in a range from 0 to 1 MPa while the correlative coefficient is 99.949%. That is the reason why the development of a totally new pressure sensor is planned, which probably finds new FBG sensing applications of pressure quasi-distributed measurement or online monitoring in industry and manufacture fields.

If you want to obtain a highly efficient 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. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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Absolutely new optical gauge allows cutting well surveillance costs

Fiber optic technology is highly promising now, in spite of the fact that fiber optic solutions found their place in numerous fields of application, the optical fiber sphere still continues developing. Thus, recently a group of researchers from the UK demonstrated a novel optical pressure-temperature gauge of compact size.

The optical gauge is considered to enlarge the fiber optic application, especially when it comes to a well surveillance area. Moreover, this optical device allows cutting all the costs and offering a new alternative to conventional downhole fiber sensors and other electronic logging tools.

Also, it should be mentioned that it is possible to combine the optical gauge with other devices, for example, with a simple deployment mechanism and distributed sensing technology, adding new properties and offering savings of 50-90% compared to traditional logging techniques.

A fiber optic gauge is a special tool that is based on fiber Bragg gratings without using electronics, external connections, or power supply equipment. Herewith, optical gauges provide the following advantages that include:

Immunity to electromagnetic fields;
Potential application in highly explosive environments;
Ability to withstand high vibration loads without any mechanical failure of sensor material;
Reduced number of connection lines and consequently, less impact on test purposes;
Low interconnection is required because of the possibility to include numerous sensors with different fiber Bragg grating wavelengths in one optical fiber.

The novel optical gauge can be installed in the fiber optic line and used in harsh atmospheres. Moreover, this fiber optic device is able to measure up to 10,000 psi (689 bar) and 150°C (302°F), optionally enlarged to 20,000 psi (1,379 bar) and 300°C (572°F).

Herein, the size of the optical gauge is about 10 cu mm, that is why the device can be easily implemented in various optical sensors and even installed in narrow access wells to log data during descent and to capture bottom hole temperature and pressure over time.

Finally, the optical pressure-temperature gauge is able to operate several months without human control, streaming real-time, live well information along with the optical fiber back to the surface. Usually, fiber optic sensors are applied in complex surveillance systems that have a high cost, sometimes they need either batteries or electrical power as well as special equipment compared to the novel optical gauges. Nevertheless, FBG sensors remain number one in the market today due to their lightweight, simple installation and relatively low cost.

If you want to obtain a highly efficient 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. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

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