Spatial resolution enhancement of a Brillouin-distributed sensor using a novel signal processing method

It is known that the ultimate spatial resolution for a Brillouin-based sens or is limited by the lifetime of the phonons in the fiber that mediate the Brillouin loss process. At optical pulse widths less than 10 ns (correspond ing to one meter spatial resolution) the Brillouin line width is considerab ly broadened, causing a severe penalty in resolving the Brillouin frequency shift. Around 5 ns the Brillouin line width is too broad to allow an accur ate frequency determination. The fiber optics group at the University of Ne w Brunswick, Canada, has recently developed an automated system for strain measurements in a distributed sensing system that uses a novel signal proce ssing technique to measure strain at resolutions finer than the Brillouin l ine width limit. Strain has been resolved to 20 mu epsilon at 500 mm and to 40 mu epsilon at 250 mm.