50 km-Range Brillouin Optical Correlation Domain Analysis With First-Order Backward Distributed Raman Amplification

• Published in: Journal of lightwave technology Vol. 38; no. 18; pp. 5199 - 5204
• Main Authors: Ryu, Gukbeen, Kim, Gyu-Tae, Song, Kwang Yong, Lee, Sang Bae, Lee, Kwanil
• Format: Journal Article
• Language: English
• Published: New York IEEE 15-09-2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplification; Correlation analysis; Data processing; Depletion; Enlargement; Frequency modulation; Optical fiber amplifiers; Optical fiber sensor; Optical fiber sensors; Probes; Raman scattering; Rayleigh scattering; Scattering; Spatial resolution; Stimulated brillouin scattering; Stimulated emission; Strain distribution; time domain analysis
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2020.3001585

We demonstrate the enlargement of sensing range of Brillouin optical correlation domain analysis (BOCDA) system by introducing the first-order distributed Raman amplification. The time-domain data processing is adopted for the BOCDA system utilizing a gated Brillouin pump, and the Raman amplification is applied to compensate for the depletion of Brillouin pump induced by Rayleigh scattering and Brillouin interaction. The Raman pump is injected in the opposite direction to the propagation of Brillouin pump, where the pumping scheme is optimized by simulations. A differential measurement scheme is additionally introduced for improving spatial resolution and dynamic range. In experiments, we measure the strain distribution along a 52.1 km sensing fiber with 7 cm spatial resolution, where the number of resolving points of measurement is more than 744 000.