Ultrasensitive fiber-optic temperature sensor based on cascaded Sagnac interferometers with a nematic liquid crystal film

• Published in: Optics and laser technology 2022-08, Vol.152, p.108169, Article 108169
• Main Authors: Fan, Xiaoya, Chen, Hailiang, Zheng, Yu, Liu, Yundong, Chen, Qiang, Zhang, Yingyue, Ma, Mingjian, Du, Huijing, Li, Shuguang, Shum, Perry Ping
• Format: Article
• Language: English
• Subjects: Biomolecules; Cascaded Sagnac interferometers; Electric cables; Fiber optics; Interferometers; Liquid crystals; Magnetic devices; Nematic crystals; Nematic liquid crystal; Optical fibers; Sensitivity; Sensors; Structural stability; Temperature; Temperature measurement; Temperature sensor; Temperature sensors; Thickness; Vernier-effect
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2022.108169

•An ultrahigh-sensitive fiber-optic temperature sensor based on cascaded Sagnac interferometers with a nematic liquid crystal film was proposed and experimentally demonstrated.•The molecules of NLC film changed from isotropic to isotropic just by rotating the two single-mode patch cables without any orientation agent, electric, or magnetic devices.•Experimental results revealed that the temperature sensor based on the cascaded configuration showed an ultrahigh sensitivity of 43.13 nm/°C, which was amplified about 5 times contrast to a single Sagnac interferometer. We demonstrated an ultrasensitive fiber-optic temperature sensor based on cascaded Sagnac interferometers (CSIs). One of the Sagnac interferometers (SIs) consisted of a panda polarization-maintaining fiber (PMF) as the reference arm, while the other one contained two single-mode patch cables in a ferrule matching sleeve as the sensing arm, where a nematic liquid crystal (NLC) film was infiltrated into the micron-scale gap of the sleeve. In the sensing SI, the orientation of NLC film was induced by just rotating the two single-mode patch cables without any orientation agent, electric, or magnetic devices. Vernier effect was acquired by adjusting the thickness of NLC film. Experimental results revealed that the temperature sensitivity of the CSIs was up to 43.13 nm/°C, which was enhanced about 5 times compared to the single NLC SI. The designed optical fiber temperature sensor possessed the merits of compact structure, high stability, ultrahigh sensitivity, low hysteresis effect and high resolution, showing a promising application prospect in some scientific filed requiring accurate temperature measurement, such as biomolecules, medicine and other filed.