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16 mm, 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-1296.78 pm/℃, 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 tapered double-cladding fiber (TDCF) temperature sensor based on surface temperature sensitive thin-film is presented. It consists of two sections of common single-mode fiber (SMF), and a TDCF is welded between them. The structure is SMF-TDCF-SMF. Because the mode field of the SMF core mode does not match that of the TDCF core mode, the light transmitted from SMF is partially coupled into the TDCF core, and the rest is coupled into the TDCF cladding in the form of a cladding mode. When the two beams reach output end SMF and interfere, the Mach-Zehnder interferometer can be obtained. The TDCF is coated with a layer of temperature-sensitive thin-film, so that the optical path difference between the TDCF core mode and the cladding mode will change with the external temperature, thus causing a change in the sensor interference spectrum. Therefore, temperature measurement can be achieved by detecting changes in the sensing spectrum. The temperature characteristics of the sensor are experimentally studied, and the results show that the free spectral range of the sensor decreases with the increase of tapered cone length. When the length of the tapered cone is 16 mm and the temperature is within the range of 32-65.3 ℃, the transmission spectrum of the sensor is blue-shifted with the increase of temperature. The temperature sensitivity is up to -1296.78 pm/℃, and it has good linearity degree. The sensor is simple, highly sensitive, and has good prospects in temperature measurement occasions of scientific research, industrial and agricultural production.