Micro-Cavity Array With High Accuracy for Fully Distributed Optical Fiber Sensing

A micro-cavity array (MCA) fiber based on a dense ultra-short fiber Bragg grating (FBG) array is proposed for high-accuracy fully distributed sensing. In the MCA fiber, each pair of adjacent FBGs forms a micro-cavity, which acts as the sensing element. The high finesse interference spectra of the micro-cavities facilitate high demodulation accuracy. Large-scale multiplexing of 8557 FBGs results in 8556 micro-cavities in a 7.18-m MCA fiber. Combined with optical frequency-domain reflectometry, fully distributed temperature sensing with a spatial resolution less than 1 mm and measurement precision of 0.157 °C is demonstrated.