Modified Sagnac/Mach-Zehnder interferometer for distributed disturbance sensing

We propose an alternative configuration for an interoferometric distributed fiber optic sensor. The sensor uses a combination of Mach-Zehnder and Sagn ac interferometers sharing the same fiber. The output of the Sagnac interfe rometer is a function of the product of the position where the disturbance was applied and the magnitude of the disturbance. The output of the Mach-Ze hnder interferometer is a function of the magnitude of the disturbance only . The position and magnitude of a disturbance applied to the sensing fiber can thus be obtained from these two signals. Results obtained with a 200 m distributed fiber sensor are discussed. (C) 1999 John Wiley & Sons, Inc.