调制频率对Φ-OTDR分布式光纤扰动传感系统动态性能的影响(英文)

Influences of modulation frequency on dynamic performance of vibration sensor based on Φ-OTDR

调制器将输入连续光调制成脉冲光,是基于Φ-OTDR分布式光纤扰动传感系统的重要组成部分,其调制频率直接决定了系统的监测距离并影响系统的动态特性。对调制频率对系统动态响应范围的影响进行了理论分析及仿真研究。结果表明,脉冲调制频率决定了系统所能还原的外界扰动信号的最高频率。调制频率越高,系统的频率响应范围越大,可探测到的扰动的极限频率越高,采集到的信号失真度越低;反之,调制频率较低甚至低于扰动信号频率时,采集到的信号将严重失真。

The acousto-optic modulator （AOM） is an important component of fiber-optic distributed vibration sensing system based on - OTDR which can modulate the CW light to pulsed light. The frequency of AOM directly affects the dynamic performance of the system. Based on the sensing mechanism of the system, the influence of modulation frequency on the frequency response was analyzed theoretically. The results show that the utmost frequency of the vibration signal regenerated by the system is limited by the modulation frequency. The range of frequency response extends with the increase of the modulation frequency, which means the limitation of frequency response increases and the distortion of the vibration signal decreases when a laser source with constant optical power is utilized. On the contrary, the high frequency vibration signal will be severely distorted when the modulation frequency is insufficient.