LAUSR

We proposed a high-resolution static strain sensor using random fiber lasers (RFLs) and the sweep-beat frequency interrogation technique. An RFL with 3-dB linewidth of 548 Hz and frequency jitter of ~±70 kHz is established by random distributed gratings and a high-precision $\pi $ -phase shifted fiber Bragg grating ( $\pi $ -FBG) ring mirror. Two RFLs act as probes and are interrogated by frequency-swept laser. One RFL is used for strain sensing, the other is used for compensating temperature and frequency shift of swept laser. By using sweep-beat frequency demodulation, a static strain resolution of 196 pico-strain ( $\text{p}\varepsilon$ ) is obtained in 160 s. To the best of our knowledge, this is the first time that RFLs have been used in static strain sensing based on sweep beat-frequency interrogation.