Improvement of Strain Measurement Accuracy and Resolution by Dual-Slope-Assisted Chaotic Brillouin Optical Correlation Domain Analysis

A dual-slope-assisted chaotic Brillouin optical correlation domain analysis (DSA-CBOCDA) technique is proposed to improve the measurement accuracy and resolution for static and dynamic strain sensing. By using the gain ratio obtained from two slopes of the Brillouin gain spectrum (BGS), the influence of random fluctuation in chaotic pump power on the measurement result is alleviated. Compared with the previous single-slope-assisted CBOCDA, the measurement accuracy of the DSA-CBOCDA is improved from 25.0 mu epsilon to 3.9 mu epsilon for the static strain, and from 28.5 mu epsilon to 6.2 mu epsilon for the dynamic strain. Meanwhile, the static strain resolution of 10 mu epsilon and dynamic strain resolution of 15 mu epsilon are verified in the experiment. Moreover, the dynamic strain measurement range of 800 mu epsilon for the proposed DSA-CBOCDA system is also experimentally confirmed, which is approximately fivefold larger than the current DSA-based Brillouin sensing system.