Raman amplifier-based long-distance remote, strain and temperature sensing system using an erbium-doped fiber and a fiber Bragg grating.

We demonstrate a novel, Raman amplifier-based long-distance sensing system for simultaneous measurement of temperature and strain using a combined sensing probe of an erbium-doped fiber (EDF) and a fiber Bragg grating. By recycling residual Raman pump power for generation of amplified spontaneous emission in the EDF after distributed Raman amplification in the transmission fiber, the overall system configuration was significantly simplified without requiring any additional broadband light source. We obtain a remote sensing operation of simultaneous temperature and strain measurement at a location of 50 km. High quality of sensing signals with a ~ 11 dB signal-to-noise ratio (SNR) is readily achieved even after the 50 km transmission with distributed Raman amplification.