We demonstrate a low-loss, long-range, single-ended distributed optical fiber sensor to measure both temperature and strain simultaneously and unambiguously. By using the Landau¿Placzek ratio and cascaded Mach¿Zehnder interferometric filters, we measure both the intensity and the frequency changes in the Brillouin backscattered signal. Strain and temperature measurements can then be independently resolved. A temperature resolution of 4 °C, a strain resolution of 290 με, and a spatial resolution of 10 m have been achieved for a sensing length of 15 km.
© 2000 Optical Society of America
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(120.6780) Instrumentation, measurement, and metrology : Temperature
(290.5830) Scattering : Scattering, Brillouin
(350.2460) Other areas of optics : Filters, interference
Huai H. Kee, Gareth P. Lees, and Trevor P. Newson, "All-fiber system for simultaneous interrogation of distributed strain and temperature sensing by spontaneous Brillouin scattering," Opt. Lett. 25, 695-697 (2000)