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 have a programme of research aimed at understanding the fundament al 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 have demonstrated a 51 km long sensing system in our laboratory, studied th e effects of polarisation changes in the fibre, investigated temperature/strain cross-sensitivity and are currently developing 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.

Relevant publications:
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).

Staff Involved Prof. D.A. Jackson Dr. D.J.Webb Dr. C.N. Pannell Dr. V. Lecoeuche

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