Sub-Nano-Strain Multiplexed Fiber Optic Sensor Array for Quasi-Static Strain Measurement

This letter presents a high resolution multiplexed strain sensor for quasi-static strain measurement based on π-phase-shifted fiber Bragg gratings (π-PSFBGs). The sensor array is composed by four π-PSFBGs in parallel with different delay lines, and a time-division multiplexing scheme is proposed to interrogate the π-PSFBGs in turn. The Pound-Drever-Hall technique and the sideband interrogation method are employed to improve the resolution and the sampling rate. In the demonstrational experiment, three-channel quasi-static strain sensing is realized with a resolution better than 0.4 n and a sampling rate of 100 samples/s.