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基于向列相液晶(NLC)和多模干涉原理,提出了一种新型的全光纤温度传感器。在两段普通单模光纤(SMF)中间熔接一段直径为200μm、长约为10cm的无心光纤(NCF),之后将其插入充满液晶的毛细管中并用胶棒密封,实现液晶封装的SM-NC-SM结构的制作。其中,液晶可视为NCF的包层,基于NLC的温度-折射率可调性和热光系数大的特性,能通过SM-NC-SM结构传播的光受到温度调制,通过检测特征波长的漂移实现外环境温度测量。实验测得在27~67℃温度范围内的灵敏度高达626.6pm/℃,并得到特征波长漂移与温度良好的线性关系,其线性度为99.23%。利用设计的传感器搭建了实用的光电检测系统,将波长漂移量的检测转换成电压大小的测量,测得相对误差小于4%。本文设计的传感器结构简单、成本低和灵敏度高,为温度传感应用提供了一种新方法。
Based on the principle of nematic liquid crystal (NLC) and multimode interference, a novel all-fiber temperature sensor is proposed. A section of centerless fiber (NCF) with a diameter of 200 μm and a length of about 10 cm was welded between two ordinary SMFs, and then inserted into a liquid crystal filled capillary tube and sealed with a glue stick to achieve a liquid crystal package SM-NC- SM structure of the production. Among them, the liquid crystal can be regarded as the cladding of NCF. Based on the NLC’s temperature-refractive index tunability and high thermal coefficient, the light propagating through the SM-NC-SM structure is temperature modulated. By detecting the characteristic wavelength shift External temperature measurement. The experimental results show that the sensitivity is as high as 626.6 ℃ / ℃ in the temperature range of 27 ~ 67 ℃ and the linearity of the characteristic wavelength drift with temperature is good. The linearity is 99.23%. A practical photoelectric detection system is constructed by using the designed sensor. The detection of the wavelength drift is converted into the measurement of the voltage, and the relative error is less than 4%. The sensor designed in this paper has a simple structure, low cost and high sensitivity, which provides a new method for temperature sensing applications.