Fiber Bragg grating sensors in smart cities

The infrastructure of modern cities is becoming increasingly more complex; it includes roads, pavements, railways, tunnels, and ducts. These structures are not only made of composite materials in which behavior under harsh environments can often be unpredictable, but they also interconnect. These systems are subjected to extreme environmental conditions, like severe winds, earthquakes, flooding, etc.; due to this, they are susceptible to catastrophic failure.

One of the main aspects of any smart city is safety. The transportation network needs to be assessed through gathering data on roadway conditions, like dangerous conditions due to roadway degradation, icing, and hydroplaning. Autonomous data gathering is vital for the safety and efficiency of the transportation network. The data gathered gives information on the inevitable roadway and infrastructure degradation over time, which enables informed decisions for life extension or timely replacement of these critical systems.

Computational tools are often not adequate for the task of condition assessment of complex infrastructure systems. These tools lack the capability to reliably predict response to extreme events. Therefore, a distributed sensor system is needed in order to ensure the safety and longevity of infrastructures in a smart city. The sensing system should also be capable of providing critical information to computational models to enable informed maintenance planning as opposed to the reactive maintenance schemes currently employed.

Fiber optic sensing systems provide the most efficient and economical solution. Fiber optic systems allow for the assessment of thousands of sensors in real-time on a single cable. FBG sensor systems are well-suited to the detection and recording

of critical structural response characteristics as well as environmental indicators that lead to degradation. FBG strain sensors are useful in the process of assessing the response to stressors, e.g. traffic, wind, earthquakes, blast events, support settlement, etc. Distributed acoustic sensing is ideal for the direct assessment of localized damage in steel and reinforced concrete that may occur due to seismic events, fatigue cracking, corrosion, etc. FBG sensors are also ideal for monitoring of weather conditions, as the presence of entrapped moisture in asphalt paving systems, as they are often the main cause of the rapid degradation.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: FBG sensors, FBG interrogators, and multiplexers, Distributed Temperature Sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world. We provide a distributed acoustic sensing system that is much less expensive than other analogous systems present on the market.

If you are interested in Optromix distributed acoustic sensing system or Optromix FBG sensor systems, please contact us at info@optromix.com

Distributed acoustic sensing

The development of modern technology and an ever-increasing need for larger volumes of production drive the optical fiber technologies forward towards more precise measurement. Optical fiber technology has been rapidly developing for the past 30 years and now approaches the theoretical limits in terms of attenuation and precision manufacturing. The refinements have been taken advantage of in many non-transmission applications, where optical fiber sensing has come to the forefront of numerous industries and applications.

There are numerous embodiments of fiber optic technologies in modern industries, that include distributed temperature sensors, FBG strain sensors, FBG strain sensors, FBG pressure sensors, FBG interrogators, FBG multiplexers, etc. One of them – Distributed Acoustic Sensing (DAS) – provides near real-time measurements by using optical fiber by taking advantage of its low attenuation and long reach. The dielectric nature of distributed acoustic sensing and its immunity to radiofrequency and electromagnetic interference also present an important benefit of DAS to multiple applications.

The technology behind distributed acoustic sensing relies on coupling coherent laser energy pulses into an optical fiber and analyzing naturally-occurring Rayleigh backscatter. As light travels from the input to the distal end, it interacts with fiber, which causes a small amount of light to backscatter. The light that returns to the input end is detected and analyzed. Acoustic waves interact with the material that constitutes the fiber create changes in the refractive index. The changes in the refractive index have an effect on the backscatter characteristics that become detectable for the system. The time-domain techniques are then used to determine the location of the event, which provides fully distributed sensing with a resolution of 1 meter or less.

Distributed acoustic sensing has been found useful and necessary for many different applications, some of which include:

  1. Oil and gas monitoring;
  2. Perimeter security;
  3. Wells monitoring;
  4. Powerlines monitoring.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators, and multiplexers, Distributed Temperature Sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world.

We provide a distributed acoustic sensing system that is much less expensive than other analogous systems present on the market. If you are interested in Optromix distributed acoustic sensing system, please contact us at info@optromix.com

Performance of fiber Bragg gratings in radiation environments

The developments in photonics led to a communication revolution over the past two decades. The technologies developed for telecommunications are now being used in the development of sensors for a wide variety of applications. The sensors based on photonic technology are especially valuable for applications where the measurements need to be taken in harsh environments like ones encountered in space exploration and nuclear power plants. Fiber Bragg grating sensors are preferred as they are compact in size, have low power consumption, and are tolerant to environmental influences.

The sensing in FBG sensors relies on using the sensitivity of the device to changes in the refractive index of the host material. In FBG sensors the resonant condition is directly proportional to the refractive index of the waveguide. A small change in the environment, for example, a temperature drop or increase, leads to a significant change in resonance wavelength which has been used for photonic thermometry. The sensitivity of FBG sensors to small changes in the refractive index raises the question of the FBG sensor performance under harsh conditions, such as high radiation environments.

The past studies have shown that FBG sensors are fully functional for several years under exposure to radiation doses ranging from a few Gy/h to a few kGy/h. Some studies have indicated a small, but significant drifts in Bragg resonances; this suggests that the resonance wavelength redshifts with increasing dose rate, however, other studies have reported a blue shift of comparable magnitude.

Overall, FBG temperature sensors show significant peak center drift due to accumulated dose, however, the temperature sensitivity shows no changes. The changes in the measurements are assumed to be due to the complex changes in the fiber. An understanding of the changes that occur in the fiber during the exposure to radiation could enable integrated dose measurements of absorbed radiation dose with the use of appropriate correction factors.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Temperature Sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world.

If you are interested in Optromix FBG sensors, please contact us at info@optromix.com

Voltage measurements with fiber Bragg gratings

Voltage measurement is essential for many fields such as power grids, telecommunications, metallurgy, railways, oil production, etc. Voltage measurements are related to fault detection and monitoring of the state of large equipment, which is essential for these fields. As the technologies used in these fields continue to develop, voltage monitoring becomes increasingly more important to the system of fault location.

Traditional voltage-sensing devices and methods are not ideal and possess multiple drawbacks, such as:

  1. Narrow bandwidth;
  2. Large weight;
  3. A possibility of combustion under heavy working conditions;
  4. Contact sensing.

Due to the multiple drawbacks of these methods, a need for a new voltage sensor has emerged. The new method of voltage measurement needs to have good amplitude-frequency characteristics and transmission characteristics in order to build smart sensing systems.

Currently, the biggest emphasis is put on fiber optic technology. Researchers attach great importance to voltage monitoring with optical elements as they offer multiple advantages that are vital for voltage monitoring in various fields:

  1. FBG sensors are passive;
  2. They are immune to electromagnetic interference;
  3. FBG sensors are compact and lightweight;
  4. FBG sensors can be mounted on any surface;
  5. They possess a wide sensing range;
  6. FBG sensors are stable under high temperatures.

The use of FBG sensors for voltage measurements allows us to obtain the data of switching overvoltage and lightning invasion overvoltage, analyze the overvoltage incidents, and overvoltage mechanisms.

Optromix R&D team, established in 2004, has extensive experience in the development of fiber optic products and solutions, based on the advanced research work and patents of internationally recognized scientists. Our main goal is to deliver the best quality fiber optic products to our clients. We produce a wide range of fiber optic devices, including our cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems.

Fiber Bragg grating for shallow landslide triggering detection

Shallow landslides pose a serious threat to structures situated in close proximity. The most dangerous are some flow-like landslides that travel at significant rates for long distances. The detaching area is the starting point for flow slides that erode and engage large amounts of soil along their path and may discharge great impact energy to engineering structures.

The detection of landslide triggers has been an important issue for many years; significant efforts have been undertaken to understand the mechanisms responsible for landslide triggering, as well as to identify the first signs of soil instability. This information will aid in the development and implementation of effective early warning systems. Among triggering, factors for a landslide are slope saturation, groundwater seepage, excavation, erosional processes, seismic action, etc. All these factors increase shear stress and pore water pressure, which in turn cause sliding surfaces due to high strain in the sliding mass. The strain increases with the approach of flow sliders; the strain increases exponentially as the landslide approaches. Soil instability follows, which causes erosion.

Therefore, the strain is the most important parameter for landslide monitoring. In recent years, fiber optic technology has attracted significant interest due to the multiple advantages that it provides. Fiber optic strain sensors are already widely used in geotechnical applications, including landslide monitoring. recently, the results of experiments involving FBG strain sensors have revealed that FBG sensors can be successfully used for measuring strain in the soil since it is possible to effectively couple the fiber cable with the soil.

One of the most attractive attributes of FBG strain sensors for landslide triggering detection is that FBG sensors do not interfere with the phenomenon that they are designated to monitor.

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators, and multiplexers, Distributed Temperature Sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world.

If you are interested in Optromix FBG strain sensors, please contact us at info@optromix.com