Phase-Gain Dual-Parametric Spectrum Measurement in Chaotic Brillouin Optical Correlation-Domain Analysis

In this paper, the chaotic Brillouin phase-gain dual-parametric spectrum (BDS) is measured for the first time, which can realize high-accuracy and large-range dynamic strain demodulation in chaotic Brillouin optical correlation domain analysis (CBOCDA). The phase of the chaotic probe wave is measured by a Sagnac interferometer (SI) combined with an optical bandpass filter (OBPF) and a beat frequency locking technique. The Brillouin gain spectrum (BGS), Brillouin phase-shift spectrum (BPS), and BDS are measured in the chaotic BOCDA system through both simulation and experiment, and the feasibility of their demodulation with high-accuracy and large-range dynamic strain is verified. The chaotic BPS exhibits good linearity at the Brillouin frequency shift (BFS) and can be used to demodulate high-accuracy tiny strains. The measurement error of a 1 με strain is only 0.0446 με. The linear range of the chaotic BDS is extended to 150 MHz, and more than 10 mε dynamic strain measurements can be enabled by incorporating the slope-assisted method.