We report on the use of second-order Raman amplification to assist a phase-sensitive optical time domain reflectometer (ΦOTDR ) used for vibration measurements over very long distances. The sensor was able to measure vibrations of up to 380 Hz (limit set by the time of flight of light pulses) in a distance of 125 km with a resolution of 10 m and no post-processing. Balanced detection is used to reduce the relative intensity noise. A comparison with a sensor using first-order Raman amplification under similar conditions is presented and a clear improvement of performance is demonstrated.

Date Published: 2 June 2014
PDF: 4 pages
Proc. SPIE 9157, 23rd International Conference on Optical Fibre Sensors, 91576K (2 June 2014); doi: 10.1117/12.2059483

Published in SPIE Proceedings Vol. 9157:
23rd International Conference on Optical Fibre Sensors
José M. López-Higuera; Julian D. C. Jones; Manuel López-Amo; José Luis Santos, Editor(s)