An interferometric technique is described to detect and locate perturbations along an optical fiber. This distributed sensor has a position-dependent response to time-varying disturbances such as strain or temperature. A modified Sagnac interferometer configuration that incorporates an additional coupler and a mirror allows separation of the Sagnac and the Mach–Zehnder signals. Operation of the new configuration was verified experimentally with a 100-m-long sensing fiber. The discrepancy between actual and measured locations of disturbances applied to the fiber did not exceed 0.6 m.
© 1998 Optical Society of America
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(130.6010) Integrated optics : Sensors
Anatoli A. Chtcherbakov, Pieter L. Swart, and Stephanus J. Spammer, "Mach–Zehnder and Modified Sagnac-Distributed Fiber-Optic Impact Sensor," Appl. Opt. 37, 3432-3437 (1998)