FBG Arrays for Quasi-Distributed Sensing: A Review

Abstract

Fiber Bragg grating (FBG) array is a powerful technique for quasi-distributed sensing along the entire length of sensing fiber with fast response and high precision. It has been widely used for temperature, strain, and vibration monitoring. In this review work, an overview on the recent advances of FBG arrays is conducted. Firstly, the fabrication methods of FBG array are reviewed, which include femtosecond laser system and online writing technique. Then, the demodulation techniques for FBG arrays are presented and discussed. Distributed static sensing can be performed by demodulating wavelength shift of each FBG, while phase demodulation techniques with low noise are employed for dynamic vibration sensing. Simultaneous distributed dynamic and static sensing system based on FBG array is also outlined. Finally, possible future directions are discussed and concluded. It is believed that the FBG array has great development potential and application prospect.

Enhancing fibre-optic distributed acoustic sensing capabilities with blind near-field array signal processing

“…In addition, further improvements could be obtained in some scenarios by pre-processing DAS measurements using deconvolution and dereverberation techniques to remove acoustic reflections 19 – 21 . We believe that the proposed technique is a starting point opening new class of acoustic processing strategies to enhance the capabilities of distributed acoustic sensors, but also other technologies like arrays of fibre Bragg gratings 46 , 47 and multiplexed interferometric fibre sensors 48 , 49 , to measure the acoustic field existing outside the optical fibre.…”

10-cm spatial resolution distributed acoustic sensor based on an ultra low-loss enhanced backscattering fiber

“…The number of sensing nodes in such an array, however, is limited to less than a hundred per fibre which may restrict the application of this approach to a relatively small scale deployment. To address this limitation, sensing systems based on ultra-weak fibre Bragg grating (UWFBG) arrays have been developed [18][19][20][21] . UWFBG arrays, used in this approach, are comprised of several hundred low-reflectivity FBGs with an identical Bragg wavelength which, unlike conventional FBG arrays, are interrogated through time division multiplexing.…”

Demodulation Algorithm for Fiber Bragg Grating Sensors

“…(1)(2)(3)(4) A fiber Bragg grating (FBG) sensor, a type of wavelength-modulated fiber optic sensor, has unique advantages in addition to the above advantages. (5) Owing to the wavelength modulation, changes in the light source intensity, link loss, and the electrical signal intensity of an optical fiber sensing system will not influence the measurement results. Therefore, FBG sensors are widely used to monitor physical parameters such as temperature, (6,7) strain, (8) and displacement in the aerospace, civil engineering, petroleum, and petrochemical fields.…”