The theoretical and experimental study on white light interferometric fiber optic sensors network based on Michelson and Mach-Zehnder interferometers

Based on the white light interferometric technology, a novel combination interferometer of Mach-Zehnder and Michelson system has been proposed and demonstrated. It consists of a Michelson interferometer and a series Mach-Zehnder interferometers which are linked to an arm of the Michelson interferometer, thus configuring a multi fiber optic sensors measuring network. It can be used to measure the distribution of strain or temperature, and it is especially suitable to monitor large-scale structural deformation, because its sensing gauge length is up to ten meters. Meanwhile, it could be used in temperature compensation mode with one arm of the Mach-Zehnder interferometer measuring the strain caused by the variation of deformation or temperature while another arm only measure the ambient temperature because it is in strain free state. Thus, this sensor arm could be used to compensate the variation of the refractive index of the fiber induced by temperature changes and the elongation of the fiber caused by thermal expansion.