Spatial-division multiplexed hybrid Raman and Brillouin optical time-domain reflectometry based on multi-core fiber

Spatial-division multiplexed (SDM) hybrid Raman- and Brillouin- optical time-domain reflectometry (RODTR and BODTR) utilizing the multi-core fiber has been proposed and experimentally demonstrated. The solution is proposed in order to overcome the incompatible input pump power required for hybrid ROTDR and BOTDR in single mode fiber (SMF), while ensuring the capability of discriminative measurement between temperature and strain. What's more, the central core has been intentionally chosen to implement BOTDR so as to avoid bending-induced cross-sensitivity on Brillouin frequency shift (BFS) measurement. The proposed system utilizes a single laser source, shared pump generation devices, but separate interrogation fiber channels, thus enabling efficient input power management for the two reflectometry, allowing for simultaneous measurement of spontaneous Raman scattering and Brillouin scattering. The worst temperature and strain resolutions are estimated to be about 2.2 °C and 40 με respectively in 6 km sensing range with 3 m spatial resolution.