Twin multiplexing strain sensing array based on a low-coherence fiber optic Mach–Zehnder interferometer

A twin multiplexed white light interferometric fiber optic strain sensor array was designed and demonstrated. In this sensing system, based on a low-coherence fiber optic Mach–Zehnder interferometer, an optical path matching technique is used to demodulate each sensor. The strain sensor array consists of 2 × N sensing elements linked by N 3 dB couplers. When one of the fiber sensors has been used to measure the strain, the variation caused by the temperature can be compensated by the other sensor. The multiplexing capacity of the sensing scheme has been analyzed. The results shown that it is depend on the light source power. The maximum number of the twin fiber sensor size is 4 for light source with 35 μW, and 7 for light source with 3 mW, respectively. The experimental result with a two-coupler sensor array was conducted and demonstrated which confirm this. It is useful for temperature compensation of distributed strain measurement in smart materials or structures health monitoring.