Slope-assisted BOTDA based on vector SBS and frequency-agile technique for wide-strain-range dynamic measurements

• Published in: Optics express Vol. 25; no. 3; pp. 1889 - 1902
• Main Authors: Zhou, Dengwang, Dong, Yongkang, Wang, Benzhang, Jiang, Taofei, Ba, Dexin, Xu, Pengbai, Zhang, Hongying, Lu, Zhiwei, Li, Hui
• Format: Journal Article
• Language: English
• Published: United States 06.02.2017
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/oe.25.001889

We present a slope-assisted BOTDA system based on the vector stimulated Brillouin scattering (SBS) and frequency-agile technique (FAT) for the wide-strain-range dynamic measurement. A dimensionless coefficient K defined as the ratio of Brillouin phase-shift to gain is employed to demodulate the strain of the fiber, and it is immune to the power fluctuation of pump pulse and has a linear relation of the frequency detuning for the continuous pump and Stokes waves. For a 30ns-square pump pulse, the available frequency span of the K spectrum can reach up to 200MHz, which is larger than fourfold of 48MHz-linewidth of Brillouin gain spectrum. For a single-slope assisted BOTDA, dynamic strain measurement with the maximum strain of 2467.4με and the vibration frequency components of 10.44Hz and 20.94Hz is obtained. For a multi-slope-assisted BOTDA, dynamic measurement with the strain variation up to 5372.9με and the vibration frequency components of 5.58Hz and 11.14Hz is achieved by using FAT to extend the strain range.