深入研究了VBOTDA(矢量布里渊光时域分析)系统的原理, 该系统在传统BOTDA(布里渊光时域分析)系统的基础上采用外差方案, 可提高系统信噪比并获得布里渊相移信息。文章提出了一种将叠加平均去噪算法与FFT(快速傅里叶变换)分析法相结合的相位解调方法——频谱算法, 进行了理论分析并搭建实验平台验证了该算法的可行性和有效性。结果表明, 该算法对不同信噪比下的信号均有较好的解调效果; 对幅值为0.3 V且噪声标准偏差为0.5 V的信号, 采用1 000次叠加平均的频谱算法, 相位相对测量误差可降至0.71%。

This paper studies in-depth the principle of the Vector Brillouin Optical Time Domain Analysis (VBOTDA) system. This system adopts a heterodyne detection scheme on the basis of the conventional BOTDA system, thereby enhancing the system Signal-to-Noise Ratio (SNR) and acquiring Brillouin phase-shift information. Then, it proposes a phase demodulation method, i.e. the spectrum algorithm that combines the superimposed average denoising algorithm with the FFT analysis. Theoretical analysis and experimental demonstration verify its feasibility and effectiveness in that it is effective in demodulating signals with different SNR and for signals with 0.3 V amplitude and noise standard deviation of 0.5 V, and the phase relative measuring error can be lowered to 0.71% when the spectrum algorithm superimposed 1 000 times is used.