Opt Express. 2023 Feb 13;31(4):6649-6658. doi: 10.1364/OE.482791.
We propose a broadband chirped-pulse conversion algorithm (BCPCA) to convert a finite-step scanning probe pulse into an equivalent broadband chirped probe pulse by convolving a chirp factor on the received signal in coherent phase-sensitive optical time domain reflectometry (Φ-OTDR). Combined with Rayleigh interference pattern (RIP) demodulation in chirped-pulse Φ-OTDR (CP-ΦOTDR), environmental perturbations, such as strain and temperature along the sensing fiber, can be quantitatively measured. The equivalent broadband chirped pulse is generated by digital processing, and its bandwidth can be increased by changing the composition of the scanning pulse. Thus, the measurable perturbation range of the system can be expanded. As a proof-of-concept experiment, a high-performance distributed strain measurement was realized on a 10 km fiber, the frequency response was 5 kHz, which is only limited by the fiber length, and the strain resolution was 8.04 / . The proposed method of generating equivalent broadband chirped pulse through the digital domain can be used as a supplement to CP-ΦOTDR.
我们提出了一种宽带啁啾脉冲转换算法（BCPCA），通过在相干相位敏感光时域反射计（Φ-OTDR）中接收信号上卷积啁啾因子，将有限步扫描探针脉冲转换为等效宽带啁啾探针脉冲。结合啁啾脉冲Φ-OTDR（CP-ΦOTDR）中的瑞利干涉图案（RIP）解调，可以定量测量沿传感光纤的应变和温度等环境扰动。通过数字处理生成等效宽带啁啾脉冲，并通过改变扫描脉冲的组成来增加其带宽。因此，可以扩展系统的可测量扰动范围。作为概念验证实验，在 10 km 光纤上实现了高性能分布式应变测量，频率响应为 5 kHz，仅受光纤长度限制，应变分辨率为 8.04 / 。通过数字域生成等效宽带啁啾脉冲的方法可以作为 CP-ΦOTDR 的补充。
