High-Sensitivity Strain Sensor Using Chaotic Correlation FLRD With Weak Fiber Bragg Grating

A weak fiber Bragg grating is used as the sensing element. The relationship between the ring down time of autocorrelation curves of the chaotic laser and the wavelength shift of the FBG caused by strain is analyzed theoretically and experimentally. The effect of strain on the central wavelength of the FBG is characterized by the ring down time of autocorrelation curve of the reflected and transmitted signals of the fiber loop cavity. The reflected signal achieves a maximal sensitivity of 0.67731 ns/ $\mu \varepsilon $ in the 0- $100\mu \varepsilon $ and 500- $600\mu \varepsilon $ ranges, where spectral interaction is weak, while the transmitted signal provides a maximal sensitivity of 0.1093 ns/ $\mu \varepsilon $ in the 100- $500\mu \varepsilon $ range. With an 8.2 m fiber loop cavity, this dual-signal method significantly extends the measurement range while maintaining high sensitivity throughout the detection range.