研究相位敏感光时域反射仪振动检测时, 高功率激光脉冲的入射使得光电探测器产生饱和现象而导致光纤前端振动传感不敏感, 低功率又满足不了远距离检测的需求。 为了解决这一问题, 采用一种新型传感结构的方法进行了理论分析和实验验证。根据入射功率的高低对光纤分段检测, 通过相应的数据处理, 实现了光纤振动全程敏感的结果。同时, 为了进一步提高该系统的振动灵敏度和信噪比, 对比分析了雪崩二极管检测与利用低噪声光电二极管检测的结果, 并比较了声光调制器与半导体光放大器的实验效果。结果表明, 当测量距离为38km时, 相比雪崩二极管检测, 利用低噪声光电二极管与掺铒光纤放大器有更高的信噪比; 相比声光调制器, 利用半导体光放大器能得到更高信噪比。该新型传感结构为光纤传感器领域的科学研究和工程应用提供了很好的参考。

When detecting vibration with a phase sensitive optical time domain reflectometer, if the incident laser power is high, the photo detector might be saturated so that the front end of optical fiber become insensitive to vibration sensing; if the laser power is relatively low, long-distance detection might be impossible. In order to solve this problem, a new type of sensor structure was used to conduct theoretical analysis and experimental verification. According to the incident of high or low power, optical fiber was segmented and detected. Through corresponding data processing, the whole process sensitivity of optical fiber vibration was realized. At the same time, in order to further improve the vibration sensitivity and signal-to-noise ratio of the system, the results of avalanche diode detection and low noise photodiode detection were compared and analyzed. The experimental results of acoustooptic modulator and semiconductor optical amplifier were compared. The results show that, when the measuring distance is 38km, compared with avalanche diode detection, the use of low noise photodiodes and erbium-doped fiber amplifiers has a higher signal-to-noise ratio. Compared with acoustooptic modulators, a higher signal-to-noise ratio can be obtained by using semiconductor optical amplifiers. The new sensing structure provides a good reference for scientific research and engineering application in the field of optical fiber sensors.