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提出了一种基于温敏薄膜的锥形双包层光纤(TDCF)温度传感器,其由两段普通单模光纤(SMF)之间熔接一段TDCF组成,呈SMF-TDCF-SMF结构。由于输入端SMF纤芯模的模场与TDCF纤芯模的模场极度不匹配,因此由SMF传输过来的光除一部分耦合进TDCF的纤芯中外,其余部分耦合进TDCF的包层中以包层模的形式向前传输。当这两束光到达输出端SMF时发生干涉,形成马赫-曾德尔干涉仪。在锥区涂覆一层温度敏感薄膜,使得TDCF纤芯模和包层模之间的光程差会随着外界温度的变化而改变,从而引起传感器干涉谱的变化,因此可以通过检测传感光谱的变化实现对温度的测量。实验研究了传感器的温度特性,结果表明:随着拉锥长度的增加,干涉光谱的自由光谱范围逐渐减小。当拉锥长度为16mm,温度在32~65.3℃范围内时,随着温度的增加,传感器的传输光谱出现蓝移现象,温度灵敏度最高可达-1296.78pm/℃,且具有很好的线性度。该传感器制作简单、灵敏度高,在科学研究和工农业生产的温度测量场合具有较好的应用前景。
A temperature-sensitive (TDF) double-clad fiber (TDCF) temperature sensor based on thermo-sensitive film is proposed. It consists of a section of TDCF fused between two ordinary SMFs and has the SMF-TDCF-SMF structure. Because the mode field of the SMF core mode at the input end does not match the mode field of the TDCF core mode, the light transmitted by the SMF is coupled into the core of the TDCF in addition to a part thereof, and the rest is coupled into the cladding of the TDCF Layer form of the forward transmission. Interference occurs when these two beams of light reach the output SMF to form a Mach-Zehnder interferometer. In the cone area coated with a temperature-sensitive film, making TDCF core mode and cladding mode optical path difference will change with the outside temperature changes, causing the interference spectrum of the sensor changes, it can detect the sensor Changes in the spectrum to achieve the temperature measurement. The temperature characteristics of the sensor are experimentally studied. The results show that the free spectral range of the interference spectrum decreases with the increase of the length of the tapered tube. When the taper length is 16mm and the temperature is in the range of 32 ~ 65.3 ℃, the transmission spectrum of the sensor shows a blue shift phenomenon with the temperature up to -1296.78pm / ℃ with good linearity . The sensor is simple to produce and has high sensitivity. It has good application prospects in the field of temperature measurement in scientific research and industrial and agricultural production.