Support: EPSRC, Furukawa
Temperature or strain may be determined continuously along the length of a single mode optical fibre by utilising the temperature or strain dependence of the Brillouin gain coefficient. We had a programme of research aimed at understanding the fundamental issues involved in the interaction of a cw and a pulsed laser source within a long optical fibre, and developing a long range distributed sensor system based on this effect. We demonstrated a 51 km long sensing system in our laboratory, studied the effects of polarisation changes in the fibre, investigated temperature/strain cross-sensitivity and are subsequently developed techniques to reduce the complexity and expense of the system and thereby enhance its commercial attractiveness. Potential applications include:
Temperature: Fire detection in tunnels, airport buildings, museums, LPG leak detection, process control.
Strain: Structural monitoring in buildings, bridges, dams and other capital structures, intruder detection, monitoring for river bank collapse.
1- D. Culverhouse, F. Farahi, C.N. Pannell, D.A. Jackson, “Potential of stimulated Brillouin scattering as sensing mechanism of distributed temperature sensor”, Electron. Lett. 25, 913 (1989).
2- X. Bao, D.J. Webb, D.A. Jackson, “22-km distributed temperature sensor using Brillouin gain in an optical fiber”, Opt. Lett. 18, 552 (1993).
3- X. Bao, D.J. Webb, D.A. Jackson, “Combined distributed temperature and strain sensor based on Brillouin loss in an optical fiber”, Opt. Lett. 16, 141 (1994).
4- X. Bao, J. Dhliwayo, N. Heron, D.J. Webb, D.A. Jackson, “Experimental and theoretical studies on a distributed temperature sensor based on Brillouin scattering”, J. Lightwave Technol. 13, 1340 (1995).
5- V. Lecoeuche, D.J. Webb, C.N. Pannell, D.A. Jackson, “A simple and efficient technique for an offset frequency shifter for Brillouin based distributed fiber sensing”, Proceedings of OFS, p. 332 (1997).
Prof. D.A. Jackson
Dr. C.N. Pannell
Dr. V. Lecoeuche