Opt Express. 2023 Feb 27;31(5):8927-8936. doi: 10.1364/OE.478611.
We have proposed and experimentally demonstrated an optical fiber strain sensor with high precision and extended dynamic range based on a coupled optoelectronic oscillator (COEO). The COEO is a combination of an OEO and a mode-locked laser, sharing one optoelectronic modulator. The feedback between the two active loops makes the oscillation frequency equal to the mode spacing of the laser. It is equivalent to a multiple of the natural mode spacing of the laser, which is affected by the applied axial strain to the cavity. Therefore, we can evaluate the strain by measuring the oscillation frequency shift. Higher sensitivity can be obtained by adopting higher frequency order harmonics owing to the accumulative effect. We carry out a proof-to-concept experiment. The dynamic range can reach 10000 . Sensitivities of 6.5 z/ for 960 MHz and 13.8 z/ for 2700 MHz are obtained. The maximum frequency drifts of the COEO in 90 mins are within ±148.03 Hz for 960 MHz and ±303.907 Hz for 2700 MHz, which correspond to measurement errors of ±22 and ±20 . The proposed scheme has the advantages of high precision and high speed. The COEO can generate an optical pulse whose pulse period is influenced by the strain. Therefore, the proposed scheme has potential applications in dynamic strain measurement.
我们提出并实验验证了一种基于光电振荡器（COEO）的高精度、大动态范围光纤应变传感器。COEO 是光学外差振荡器和锁模激光器的组合，共享一个光电调制器。两个有源环之间的反馈使振荡频率等于激光的模式间隔。它等效于激光的自然模式间隔的倍数，而激光的自然模式间隔受腔中轴向应变的影响。因此，我们可以通过测量振荡频率的偏移来评估应变。由于累积效应，采用更高的频率阶次谐波可以获得更高的灵敏度。我们进行了一个概念验证实验。该传感器的动态范围可达 10000 。在 960 MHz 下，获得了 6.5 z/ 的灵敏度，在 2700 MHz 下，获得了 13.8 z/ 的灵敏度。在 90 分钟内，COEO 的最大频率漂移在 960 MHz 下为±148.03 Hz，在 2700 MHz 下为±303.907 Hz，对应测量误差分别为±22 和±20 。所提出的方案具有高精度和高速的优点。COEO 可以产生一个光脉冲，其脉冲周期受应变的影响。因此，该方案在动态应变测量中有潜在的应用。
