The fiber optic sensors also called as optical fiber sensors use optical fiber or sensing element. These Sensors can measure a large variety of parameters, such as temperature, pressure, strain, refractive index, vibrations, displacements, bending, loading, and liquid level or concentration of chemical species.
Over the past decade, the proliferation of fiber optic sensors and sensing systems has been ever-increasing, especially the use of fiber Bragg grating (FBG) based sensors.
Fiber optic sensors have become a focus in the field of sensing technologies by right of their many advantages such as compact, light-weighted, high sensitivity, high multiplexing, anti-electromagnetic interference and ease to be embedded into the material. Following the development of optical fiber communication industry, optical fiber sensing technologies become another major industry of optoelectronic technologies
Fiber Bragg grating (FBG)
A fiber Bragg grating (FBG) is a microstructure within the core of an optical fiber comprising a periodic modulation of the refractive index of the underlying glass material. If broadband light guided within the core hits on this periodic microstucture one specific wavelength gets reflected and all other wavelengths of the guided broadband light can pass unhindered. The fundamental principle behind the operation of an FBG is Fresnel reflection, where light traveling between media of different refractive indices may both reflect and refract at the interface.
A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror. Hence a fiber Bragg grating can be used as an inline optical fiber to block certain wavelengths, can be used for sensing applications, or it can be used as a wavelength-specific reflector
The periodicity of the FBG defines which specific wavelength gets reflected and is perpetually inscribed into the glass like a spectral finger print. Only if an external force or change in temperature is induced to the microstructure, the periodicity of the FBG will change slightly leading to a specific wavelength shift of the light reflected at the FBG
A fiber Bragg grating (FBG) is a microstructure typically a few millimeters in length that can be photo inscribed in the core of a single-mode fiber. This is done by transversely illuminating the fiber with a UV laser beam and using a phase mask to generate an interference pattern in its core. This will induce a permanent change in the physical characteristics of the silica matrix. This change consists in a spatial periodic modulation of the core index of refraction that creates a resonant structure.
The different methods of creating these fringes have a significant effect on physical attributes of the produced grating, particularly the temperature response and ability to withstand elevated temperatures.
FBGs are being increasingly adopted across numerous applications, owing to their advantages such as direct absolute measurement, unique wavelength multiplexing capability, and nonconductivity. Moreover, they are electrically passive and immune to EMI-induced noise.
Fiber bragg grating is designed to withstand any intense mechanical, electrical, and electromagnetic stresses. They have a stable structure, which makes them ideal for telecom applications, including add/drop, filters, dense wavelength division multiplexing, mux/demux, and lasers.
These sensors can detect temperature change, strain, and pressure fluctuations. They offer higher accuracy and longer stability. Moreover, they are compact. Owing to these factors, the fiber bragg grating sensors are among the most preferred sensors in measuring, monitoring, and sensing applications across various industries such as oil & gas, aerospace, power, telecommunication, civil, and transportation.
Fiber bragg grating sensors are being implemented to locate variations in vibration, temperature, and sound in aircraft and its components. With continuous technological developments and a decrease in telecommunications devices and equipment costs, FGBs are now getting utilized as sensors.
When fiber bragg grating is used with a high-power tunable laser, they can conduct measurements over long distances with minimal or no loss in signal integrity. In addition, every optical channel can measure dozens of fiber bragg grating sensors, unlike electrical sensing systems. This, in turn, lowers the size, complexity, and weight of measurement systems. Moreover, as fiber bragg grating provides direct absolute measurement compared to old, conventional electric & alternative fiber sensors, these are being used in medical, aircraft, research & development, industrial, and telecommunication applications. Hence, due to the advantages of fiber bragg grating, their adoption rate is booming, which is another driving factor for the fiber bragg market.
In medicine, the ability to perform all the fiber optic solutions’ benefits is very useful for operations and certain medical procedures. Fibers can be inserted in hypodermic needles or catheters. That allows for more precise positioning of the fiber optic sensors. Moreover, fiber Bragg grating sensors are applied for temperature profiling near patients’ internal organs. And finally, FBG sensors are produced for endoscopic/colonoscopic pressure profiling. Fiber optic technology has an impact on chemical and biochemical sensing. There are bioassays based on fiber Bragg gratings as the sensing element for protein or DNA interactions. Nowadays, because of the development of fiber optic solutions, new fiber Bragg gratings were created. They are able to cope with high temperatures and harsh environments. It is highly useful and even crucial in power plants and for combustion and jet engines.
FBG is majorly a sensor of strain and temperature, and hence, it is utilized as a sensor for obtaining measurements of load, temperature, strain, tilt, vibration, pressure, and displacement. It also helps measure the presence of several biomedical, chemical, and industrial substances in both dynamic and static modes of operation
Acting as a strain sensor
An FBG has unique characteristics to perform as a sensor. For example, when the fiber is stretched or compressed, the FBG will measure strain. This happens because the deformation of the optical fiber leads to a change in the period of the microstructure and of the Bragg wavelength
Acting as a temperature sensor
Sensitivity to temperature is also intrinsic to a fiber Bragg grating. In this case, the main contributor to Bragg wavelength change is the variation of the silica refraction index induced by the thermo-optic effect. There is also a contribution from thermal expansion which alters the period of the microstructure. However, this effect is marginal given the low coefficient of thermal expansion of silica.
One of the main advantages of this technology is its intrinsic multiplexing capability. In fact, hundreds of fiber Bragg gratings can be written on a single optical fiber, which can be as close as a few millimeters or separated by a few kilometers. With proper packaging, each of these microstructures can be made sensitive to parameters other than temperature or strain.
For example, pressure, acceleration, displacement, etc., grants the array of sensors a multifunctional characteristic. It is important to emphasize that all the sensors can be addressed using a single optical source. Also, the addition of more and more sensors on the same fiber results in only minor loss and no crosstalk, as long as enough spectral band of the spectrum of light is reserved for each sensor
Being a fiber optic sensor, a Bragg grating has all the advantages usually attributed to these devices, such as low loss relative to the fiber length, immunity to electromagnetic and radio frequency interference, small size and weight, intrinsically safe operation in environments characterized by hazardous materials, high sensitivity and long-term reliability. In addition, fiber Bragg grating technology reveals an inherent serial multiplexing capacity and an ability to provide absolute measurements without the need for referencing. This makes it the natural alternative to conventional electrical sensing technologies.
Fiber Bragg Grating Market
Global Fiber Bragg Grating (FBG) Market size & share revenue was valued at around USD 1428.4 million in 2021 and is estimated to grow about USD 5167.4 million by 2028, at a CAGR of approximately 23.9% between 2022 and 2028.
Fiber bragg grating is used for different purposes, including structural health or strain monitoring of engineering structures such as footbridges, bridges, skyscrapers, dams, and aircraft wings; monitoring the behavior of ultrahigh quality precision tools, optical telescope, robotic surgical instruments, and more; and measuring nanometer level deformations in structures that lead to the beginning of cracks. Civil and geotechnical engineering; energy production, conversion, storage; security and perimeter monitoring; commercial transportation; performance vessels, vehicles, equipment; and medical & biotech are some additional applications where fiber bragg grating are being used. With the rising applications of fiber bragg grating globally, their adoption rate is also booming, which, in turn, is driving the market.
The rising demand for effective sensors capable of detecting several physical characteristics such as temperature, pressure, and acoustic waves in any given environment, the FBG market is likely to rise at a faster rate over the forecast period. The aircraft sector is known for its harsh and complicated operating environment, so selecting a sensor that can resist such extremes while also delivering the requisite accuracy, reliability, precision, and repeatability is critical. Furthermore, in aircraft protection systems, fiber optic technology configures easier and faster solutions for aircraft manufacturers to install more reliable and lighter weight solutions in order to measure and monitor the temperature along the aircraft bleed air ducts, control valves, and in critical areas of the plane.
Additional uses for fiber bragg grating include civil and geotechnical engineering, energy generation, conversion, and storage, security and perimeter monitoring, commercial transportation, performance boats, vehicles, and equipment, and medical and biotech. With the growing number of applications for fiber bragg grating around the world, their acceptance rate is also increasing, propelling the market forward.
Fiber Bragg Grating (FBG) Market: Segmentation Overview
By Type, the global market is distinguished into FBG Sensors and FBG Filter, and others. Sensors have revolutionized the supply chain of a variety of sectors, since the technology has substantially decreased human labor, enhanced accuracy, and saved a significant amount of time. Furthermore, technological advancements cleared the stage for automation. The majority of sensors are electric sensors, which require electricity and are susceptible to electromagnetic waves, which can cause the sensor to fail. The distributed bragg reflector architecture of fiber bragg grating sensors reflects a certain wavelength of light. Temperature, tension, and pressure variations can all be detected with these sensors.
By Application, the global is segregated into Telecommunication, Aerospace, Energy and Utilities, Transportation, and Others. The Aerospace Industry is expected to Grow Significantly. The aircraft sector is known for its harsh and complicated operating environment, so selecting a sensor that can resist such extremes while also delivering the requisite accuracy, reliability, precision, and repeatability is critical. Furthermore, in aircraft protection systems, fiber optic technology configures easier and faster solutions for aircraft manufacturers to install more reliable and lighter weight solutions in order to measure and monitor the temperature along the aircraft bleed air ducts, control valves, and in critical areas of the plane.
Key players include AOS GmbH, Alnair Labs Corporation, FBGS Technologies GmbH, HBM Fibersensing S.A., ITF Technologies, Ixblue Photonics, Micron Optics, Proximion AB, Technica,
A few developments by key players are listed below:
- In 2020, Luna Innovation Incorporated signed a US$ 6.2 million deal with Lockheed Martin to extend their long-term relationship, resulting in the development of new optical measurement products, which ensures that the global fleet of F-35 aircraft is ready for service.
- In 2018, Proximion AB entered into a development partnership for the industrialization of fiber optic sensing systems with SKF. The two companies are working together to combine SKF’s fiber optic bearing sensing technology with Proximion’s application integration experience and knowledge in developing and producing advanced fiber optic sensors and data collection hardware units.
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