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

FBGs made of doped fibersThe 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

Fiber Bragg gratings make semiconductor lasers more stable

FBGs for lasersResearchers 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 technologyIt 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.

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

FBG accelerometers measure acceleration and vibration on trains

FBG accelerometers for train monitoringNowadays 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

The use of fiber optic sensing solutions on active warships

FBGs for active warshipsThe 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

NASA offers collaboration to companies providing fiber optic solutions

FBGs in fiber optic solutionsThe members of NASA company have decided to offer collaboration to companies providing fiber optic sensing solutions for monitoring of structures and asset management. The fact is fiber optic sensing technology unifies advanced optical fiber sensors and innovative algorithms that allow making precise and cost-efficient monitoring of numerous crucial parameters in real-time.

The mentioned abilities of fiber sensing solutions play a significant role in structural health monitoring and tank gauging applications. The following parameters are taken into consideration: position or deformation (2D and 3D displacement, twist, and rotation), the level of stiffness (bending, torsion, and vibration), operational loads (bending moments, shear loads, and torques), magnetic fields (different defects in safety-critical structures made from metal materials), and stress/strength parameters such as pressure or fatigue and breakage prediction.

Moreover, fiber optic sensing systems enable to provide not only the structural health monitoring of a tank but optical fiber technology is able to sense the inventory of the tank: for example, the level of the tank’s content, evaporation rate, temperature (that can varies from cryogenic up to 300 degrees Celsius), and stratification (oil vs. water, sediment vs. liquid, and thermal layers).

Fiber optic sensing solutions offer numerous advantages that include:

  • low cost opening new fields of application across industries;
  • low  power consumption of fiber sensors due to highly efficient  algorithms and high-speed processing platform enabling quick  data processing and real-time analysis;
  • fast speed and high level of efficiency;
  • precise and adaptive fiber optic technology because of the ability of optical fiber sensors to automatically increase resolution  where/when needed;
  • easy installation of fiber device;
  • high reliability of operation even in humid/liquid environments and harsh temperature conditions.

The numerous abilities of fiber optic sensing systems create a potential solution for a myriad range of monitoring applications. Structural health monitoring and integrity, tang gauging, active control, safety and protection area, non-destructive evaluation, and medical usage refer to potential optical fiber applications.

The principle of fiber sensor operation is based on the use of fiber Bragg grating sensors that are installed in an optical fiber at intervals as small as 0.25 inches (0.64 cm). Finally, such a fiber optic sensing system allows monitoring strain, stresses, structural instabilities, temperature distributions, and numerous other engineering parameters in real-time with a single instrumentation system which weight is less than 10 pounds (4.54 kg). Herewith, the fiber optic solution is able to differentiate between liquid and gas states in a tank or other container, offering precise measurements.

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

Fiber optic solutions for fire detection and temperature measurement

FBGs for fire detectionProper fire detection in the mining area is the number one priority because fire can evoke damages to valuable assets, downtime in operation, and even loss of lives. Herewith, the installation of fire protection devices can be complicated by harsh environmental conditions of the mining area because industrial equipment produces dirt, dust, humidity, and corrosive atmospheres in the production, storage, or transport of goods. Nevertheless, the application of modern fiber optic sensors based on distributed temperature sensing or DTS is considered to be a proven and efficient technology for fire detection and temperature measurement.

The fact is DTS technology provides precise temperature measurement along the length of a conveyor belt due to the use of autonomous fiber optic cables, therefore, even very long conveyor routes can be efficiently monitored. Thus, cases of fires and overheating during mining operations can be quickly and easily identified and localized to within one-meter precision by distributed temperature sensors, enabling to activate the safety countermeasures. Also, it should be mentioned that it is required the proper installation of the fiber optic sensor cables and adjustment of the alarm zones for heat detection of industrial rollers.

Nowadays mining industry applies fiber optic linear heat detection systems for these purposes, however, the new distributed sensing technology may significantly improve and increase the protection of assets in combination with the one mentioned above. The principle of DTS technology operation is based on the use of optical fibers as a distributed microphone, moreover, it means that fiber optic sensors allow measuring not only the temperature but also the acoustics. Such additional information is important because it helps to determine potential sources of danger and improves the whole purpose of fire prevention. To be precise, the DTS is highly important in hot roller detection that is the main reason for conveyor fires.

Also, it is difficult to identify the initial smoldering stage with traditional techniques, herewith, the majority of common gas detecting systems do not work properly because of high air currents. An optical fiber-based on distributed temperature sensing technology, in its turn, provides numerous benefits during both normal operation and dangerous situation that include:

  • Reliable fiber optic cable that is resistant to dirt and dust;
  • Long-distance (up to 10 km) and up to 4 measurement channels monitor several conveyors with one DTS system;
  • Practically maintenance-free;
  • Accurate localization of fires and hot rollers;
  • DTS is able to detect fires in spite of unfavorable environmental conditions.

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

Fiber optic cables for earthquake monitoring

FBG sensors for earthquake monitoringNowadays researchers from California are planning to use “dark fiber optic cables”, i.e. unused fiber cables, for underground monitoring of sound waves or signals came from earthquakes. It should be noted that today millions of fiber optic cable miles remain unused underground in spite of the fact that they have numerous applications.

Thus, the researchers have developed a new technique of fiber optic underground monitoring that allows higher-resolution measurements of the Earth’s crust movement than the seismic detector networks could offer at the present time. Herewith, in traditional seismology the number of optical sensors for earthquake detection is limited but this technology makes each couple of meters a separate sensor.

Also, today’s problem is the measurement of the Earth’s surface vibrations because, in some seismically active places, there are a lot of fiber optic sensors while the areas that are far from tectonic plates have only a few. That is why it remains difficult to take measurements in places with fracking-induced earthquakes.

The new technique is based on distributed acoustic sensing that includes laser pulses with the aim of vibration detection along with the fiber. Moreover, the researchers use FBG interrogators that are placed along the fibers that transmit and detect short infrared laser signals.

The principle of the interrogator operation includes the detection of tiny strains caused by seismic activity on the fiber, then they force the laser light to reflect and bounce back to the fiber sensor. Thus, the researchers are able to determine light changes scattering over time by analyzing the rapid pulses, and this information shows where the seismic activity occurred.

The technology of distributed acoustic sensing was tested in real-world conditions and enable to extract information about the speed of waves traveling through the Earth’s surface. Moreover, the researchers succeeded in the earthquake measurement that happened in Mexico due to the distributed acoustic method and used fiber optic cables.

The potential application of DAS technology is the determination of groundwater location, nevertheless, the tests were not successful although the researchers could measure passing trucks and trains.  Unfortunately, this experimental method is not ready for application beyond research yet because there are a lot of limitations. For example, now a single sensing location along the line is less sensitive than a single seismometer and is able to measure the fiber strain only in one direction. The second problem of fiber optic cables is a huge amount of data that are difficult to manage, store, and organize. Herewith, the new DAS technique cannot be used yet on underwater lines.

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 creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in acoustic measurement systems and want to learn more, please contact us at info@optromix.com

Fiber optic solutions for security monitoring system

FBGs for security monitoringRecently a new simple low-cost technology has been developed for security monitoring of the borders. Initially, the technology that includes fiber-optic cables has been tested at the US-Mexico border. It allows the determination of a wide range of invasions such as animals, people, vehicles and it is even possible to detect their precise location.

In spite of the fact that this fiber-optic application is not new and has been around for years, the government of the USA has been slow to use it. The fiber-optic cable technology is able to detect exactly what is moving above it, and it does not matter whether it is a huge man, a group of people, a passing car, or a wandering dog.

Today, the US government continues to build a border wall that critics name a “medieval” solution to provide security, even despite the fact that the use of the fiber-optic system is cheaper than the building of a real wall. Other advantages of fiber optic cables include:

  • precise determination of border invasion location;
  • accurate detection of border invaders;
  • possibility to send quickly the information to border patrol agents in real-time.

It should be mentioned that only 1% of human communications is accounted for by satellites, and 99% is accounted for by fiber-optic cables spreading across the seafloor, buried under cities. Herewith, comparing to satellites, the fiber-optic technology is able not only to transmit data but also to determine movement that makes it more advantageous.

Moreover, the fiber-optic technology is already developed enough to be implemented in the security monitoring system of the US-Mexico border, and it is nearly ten times cheaper than a wall and can be put into operation instantly. Nevertheless, the main obstacle is the support of the US government.

The fiber-optic system is quite simple, that is why it is not necessary to put any sensors on the fiber because the fiber itself is a sensor that is able to determine motion as well as events anywhere along the fiber-optic cable length. Some companies made some improvements and enlarge the field of fiber-optic applications that now includes telecommunication, security monitoring, and even broadband internet access.

The principle of work is based on converting sound waves into acoustic information. Although the fiber-optic technology on its own will not completely get rid of the activity such as illegal border-crossing and drug-smuggling, its combination with border patrol agents will significantly improve the situation.

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

Fiber optic spark monitoring for EDM

FBG sensors for EDMEDM or electrical discharge (spark) machining is the most advanced of metalworking technologies. EDM is worldwide used because of its high accuracy and machining applications where traditional metal removal is highly difficult or even impossible.

The principle of EDM operation includes the spark that moves from the wire electrode to the work item approximately at the same speed as the electrical signals transmitting through the wires of the monitoring system. Nevertheless,  the distance between this work item and the wire electrode is shorter than the space interval between the spark and the control, that is why there are some difficulties in monitoring.

Thus, spark monitoring is very important and needs some technical improvements. Fiber optics is the best solution for the challenge that provides a high level of process control, increases the life of the wire, and eliminates the possibility of wire damage. Moreover, the use of a fiber optic spark monitoring system improves the problem of slow electrical signals and thereby, allows making timely all required adjustments and maintaining permanent sparks.

The main aim of fiber-optic cable use is the reduction of wire wear to save costs for the user. For example, previous machines had stronger sparks and low frequency that provoked high wire pressure. Novel fiber monitoring systems have a higher number of sparks per second with less intensity.

It should be mentioned that fiber-optic cables are not limited by the electricity speed comparing to electrical wires because fiber cables transmit data through light pulses. Moreover, they are almost one hundred times faster than electrons. This improvement allows not only reducing wire wear but also keeping spark output and decreasing the necessary voltage.

Also, fiber optic cables leave behind electrical wires because of the following reasons:

  • safety due to nonconduction of fiber optics;
  • lightness despite the required power and distance;
  • higher data bandwidth at longer distances;
  • faster transmission speed;
  • the thinness of the cable;
  • the durability of fiber cables;
  • better reliability;
  • lower total costs.

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

Total information about fiber optic temperature sensor

FBG temperature sensorsToday all modern industries include highly complex and sensitive operations that require permanent operational conditions that are possible to provide due to the use of advanced technologies for temperature measurement. One of the potential solutions is the use of fiber optic temperature sensors.

 

There are several ways of temperature measurement: classic mercury glass thermometer, infrared pyrometer, electronic thermometer. However, the most effective method is fiber temperature sensing because it provides accurate measurement compared to the mentioned techniques and has numerous fields of application such as high voltage machines, nuclear power plants, chemical power plants, etc.

The types of fiber temperature sensors include interferometric and non-interferometric sensors. The traditional non-interferometric sensor has multi-mode optical fiber construction and materials that are sensitive to temperature. Also, they are able to register changes, for example, absorption, transmission, and reflection parameters due to temperature variation.

The simple interferometric fiber optic temperature sensors are more flexible and provide the sensitivity of a higher level. The fields of the use include temperature, pressure, rotation, strain, etc. The principle of the operation is the comparison of the beam phase through sensing fiber with the reference beam.

The advantages of optical temperature sensors:

  • Immunity to electromagnetic and stray radiation;
  • Possibility of the use in hard electrical conditions;
  • Greater accuracy and faster response time;
  • Lightweight and compact size;
  • Low cost;
  • Wide temperature measurement range.

Nevertheless, fiber optic temperature sensors are not ideal and have some disadvantages such as different temperature ranges of operation and measurement accuracy for different types of sensors, the difficulties of development expensive price for some optical sensors.

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 creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in temperature measurement systems and want to learn more, please contact us at info@optromix.com