FBG has been considered as an excellent sensor element, which is currently receiving more and more research interest. In order to measure strain/temperature variations with high accuracy, the ability to detect small shifts in Bragg wavelength becomes an essential requirement for an FBG sensing system.
With the construction of high buildings and bridges, etc., in recent years, the importance of structural health monitoring technologies to assess building safety is being re-examined. In previous systems using electrical strain sensors, every sensor required power supply, and the installed sensors were easily affected by electromagnetic noise, thunderstorms, etc., causing noise components in the electrical signal measured by remote sensing and presenting a risk of degraded accuracy. Optical fibers have been used as sensors to solve these problems with a focus on optical sensing technology. Since optical sensing technology does not require supplying power to the sensor itself, it offers many advantages including long life spans with excellent corrosion resistance, excellent explosion-proofs, easy remote measurement at distances of more than 10 km with no concerns about electromagnetic noise effects, etc. In addition, the characteristics of optical fibers lend them to linear and sheet designs for extreme environments, making them ideal for disaster monitoring and structural health monitoring systems.
Some of the well-known technologies in optical fiber sensing rely on measuring changes in the frequency of Brillouin backscatter occurring in optical fibers to determine structural deformations and temperature changes. Another method uses a Fiber Bragg Grating (FBG) forming a diffraction grating at the optical fiber core as a sensor to measure changes in the center wavelength of the optical spectrum reflected from the FBG sensor as an index of the amount of strain impressed on the fiber and temperature changes. Since FBG sensor monitors are used mainly for natural disaster and structural health monitoring they are designed to be convenient for installation, small, and lightweight. Additionally, to be able to measure small strain and temperature changes quickly, they require a high responsivity of better than 1 kHz as well as better measurement accuracy than commercially available FBG sensor monitors and our previously developed model.