Qi Di, Li Jingyu, Guan Xun, Chan Chun-Kit
Opt Express. 2022 Feb 28;30(5):7725-7736. doi: 10.1364/OE.450977.
We propose a dynamic polarization-insensitive Brillouin optical time domain analyzer (D/PI-BOTDA) with orthogonal frequency division multiplexing (OFDM) based on intensity-modulated direct-detection (IM-DD). A polarization-division-multiplexed (PDM) pump signal enables polarization diversity of the stimulated Brillouin scattering while a multi-frequency OFDM probe signal realizes dynamic sensing with single-shot transmission. We experimentally demonstrated distributed temperature sensing along a total 940-meter fiber with a temperature sensing coefficient of 1.2°C/MHz. The experimental results indicated a remarkable suppression of Brillouin gain fluctuation up to 4.38 times compared to the case without polarization diversity. To facilitate the Brillouin frequency shift (BFS) extraction process, we also implement a CNN-based BFS extraction method with SE-Res2Net block. The adopted algorithm achieves a higher accuracy than conventional curve fitting method, with a 10-time enhancement in the time efficiency.
我们提出了一种基于强度调制直接检测（IM-DD）和正交频分复用（OFDM）的动态偏振不敏感布里渊光时域分析仪（D/PI-BOTDA）。偏振分复用（PDM）泵浦信号实现了受激布里渊散射的偏振分集，而多频OFDM探测信号则通过单次传输实现了动态传感。我们通过实验证明了沿总长940米的光纤进行分布式温度传感，温度传感系数为1.2°C/MHz。实验结果表明，与无偏振分集的情况相比，布里渊增益波动得到了显著抑制，高达4.38倍。为了便于布里渊频移（BFS）提取过程，我们还实现了一种基于卷积神经网络（CNN）的带有SE-Res2Net模块的BFS提取方法。所采用的算法比传统曲线拟合方法具有更高的精度，时间效率提高了10倍。
