Pico-Strain Resolution Multiplexed Fiber Grating Sensor Array Interrogated With Mode-Locked Laser

A multiplexed fiber grating sensor system based on injection-locking and high-order Pound-Drever-Hall techniques is presented. In the sensor system, two distributed feedback fiber lasers and a mode-locked laser are employed as the sensor array and probe laser, respectively. The weak comb teeth of the modelocked laser are injection locked to corresponding sensing elements, to suppress the free running noise of the laser sensors and thus interrogate the sensor array. A high strain resolution of 72 pε in 100 s and 4 pε/√ Hz above 10 Hz is proved. The proposed method allows the direct use of optical frequency comb as the light source in fiber grating sensor system. We believe this achievement is of great significance for fiber grating sensors in both sensing resolution and multiplexing scale.