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 monitoring of various facilities all over the world.
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