Millimeter-Level-Spatial-Resolution Brillouin Optical Correlation-Domain Analysis Based on Broadband Chaotic Laser

We propose and demonstrate a millimeter-level-spatial-resolution Brillouin optical correlation-domain analysis system based on a broadband chaotic laser, where the spatial resolution only depends on chaotic signal bandwidth. By adjusting the bandwidth of chaos, the single correlation peak has been compressed to be extremely narrow. The Brillouin gain spectrum was obtained by replacing a previous optical power meter with a lock-in amplifier. Thus, the signal-to-noise ratio improved and the data acquisition time reduced effectively. This experiment is the first in that the distributed tensile strain was observed via a chaotic Brillouin optical correlation-domain analysis system with a 3.5-mm spatial resolution over 165-m measurement range. The standard deviation in the reconstructed Brillouin frequency shift was ±2 MHz. To the best of our knowledge, the proposed system is a broadband-source optical sensing system with the highest reported spatial resolution.