为了测量液位在警戒值附近变化的情况, 采用新款光纤熔接机制作了一种基于锥形结构的长周期光纤光栅测量液位的光纤传感器, 对传感器进行了理论分析, 搭建了液位传感实验系统, 根据传感器对外界环境的折射率灵敏度, 测量浸没在液体中的光纤长度。结果表明, 在0 mm~12 mm的液位测量范围内, 光纤液位传感器的峰值波长灵敏度和透射功率灵敏度分别是0.700 nm/mm和1.377 dB/nm。该传感器对液位变化测量较为准确, 且采用刻栅方式可有效解决传统长周期光纤光栅中存在的非对称模耦合和偏振依赖性高等问题, 同时具有制作简单、成本低和应用前景广泛等优点。

In order to measure the change of liquid level near the warning value, a new optical fiber fusion splicer was used to fabricate a fiber optic sensor for measuring liquid level based on long-period fiber grating with tapered structure. The refractive index sensitivity of the liquid level sensing experimental system was built to measure the length of the optical fiber immersed in the liquid. The results show that in the liquid level measurement range of 0 mm~12 mm, the peak wavelength sensitivity and transmission power sensitivity of the optical fiber liquid level sensor were 0.700 nm/mm and 1.377 dB/nm, respectively. The sensor is more accurate in measuring the liquid level change, and the grating method mentioned above can effectively solve the problems of asymmetric mode coupling and high polarization dependence in the traditional long-period fiber grating,and it has the advantages of simplicity, low cost and wide application prospects.