针对腐蚀后的薄包层保偏光纤对外界溶液折射率敏感的特性,提出了一种基于高双折射环形镜的光纤液位检测方法。HF腐蚀后的保偏光纤构成高双折射环形镜中的传感头,液位的变化导致保偏光纤传输特性的变化从而实现传感测量。经测量,保偏光纤4个有效波谷点谐振波长在1 520～1 620 nm光谱范围内,且随着液面高度的上升整体向长波方向移动。结果表明,传感器灵敏度高达在0.277 nm/mm,液面高度与波长飘移量的线性度达99.5%以上,测量精度可达毫米级。

A new optical fiber liquid level sensor based on high birefringence fiber loop mirror (Hi-Bi FLM) is proposed for the thinned polarization maintaining fiber (PMF) has sensitivity to the refractive index of the external surrounding. The Etched PMF by HF, whose transmission spectrum can be transformed by the variation of the liquid level, is regarded as a sensing head in the FLM. The measurement will be monitored by detecting the variation of liquid level. Four resonant dips wavelength are in the range from 1 520 nm to 1 620 nm and shift to longer wavelength since the liquid level increases. Experimental results show that the water level sensitivity reaches up to 0.277 nm/mm, the linearity between the liquid level and wavelength drift is up to 99.5% and the measurement precision can reach millmeter level.