Ultra-Long-Distance Hybrid BOTDA/Ф-OTDR

• Main Authors: Yun Fu, Zinan Wang, Richeng Zhu, Naitian Xue, Jialin Jiang, Chongyu Lu, Bin Zhang, Le Yang, David Atubga, Yunjiang Rao
• Format: Article
• Language: English
• Published: MDPI AG 2018-03-01
• Series: Sensors
• Subjects: fiber optics sensors; optical time domain reflectometry; Rayleigh scattering; stimulated Brillouin scattering; optical amplifiers
• Online Access: http://www.mdpi.com/1424-8220/18/4/976

In the distributed optical fiber sensing (DOFS) domain, simultaneous measurement of vibration and temperature/strain based on Rayleigh scattering and Brillouin scattering in fiber could have wide applications. However, there are certain challenges for the case of ultra-long sensing range, including the interplay of different scattering mechanisms, the interaction of two types of sensing signals, and the competition of pump power. In this paper, a hybrid DOFS system, which can simultaneously measure temperature/strain and vibration over 150 km, is elaborately designed via integrating the Brillouin optical time-domain analyzer (BOTDA) and phase-sensitive optical time-domain reflectometry (Ф-OTDR). Distributed Raman and Brillouin amplifications, frequency division multiplexing (FDM), wavelength division multiplexing (WDM), and time division multiplexing (TDM) are delicately fused to accommodate ultra-long-distance BOTDA and Ф-OTDR. Consequently, the sensing range of the hybrid system is 150.62 km, and the spatial resolution of BOTDA and Ф-OTDR are 9 m and 30 m, respectively. The measurement uncertainty of the BOTDA is ± 0.82 MHz. To the best of our knowledge, this is the first time that such hybrid DOFS is realized with a hundred-kilometer length scale.