Study On Taper Mach-Zehnder And Miniature Fabry-Perot Optical Fiber Temperature Sensing Technology

Temperature is an essential physical parameter in human production and life.The measurement and perception of temperature are usually realized by sensors.With the advance of technology and the continuous improvement of production level,the requirements for the performance of sensors are also higher and higher.Compared with ordinary temperature sensors,optical fiber temperature sensors gradually play an increasingly important role in the sensing field due to their unique physical advantages.To prepare sensor components integrated into communication systems,two types of interferometric optical fiber sensors are proposed in this paper.The different types of sensing devices are combined with temperature-sensitive materials to produce temperature sensors that are more sensitive to temperature response.The research content of this paper includes the following two aspects:(1)An Mach-Zehnder interferometric temperature sensor using nano-material encapsulated taper microfiber is proposed.The sensor is prepared by encapsulating boron nitride(BN)dispersion around taper microfiber with capillary and fixed with ultraviolet(UV)glues.The decrease of the diameter of the microfiber can improve the performance of the sensor but reduce its stability.Therefore,the microfiber with a diameter of 12.3 μm is selected.Due to the high thermo-optical coefficient of the BN dispersion,the temperature sensing performance of the sensor is greatly improved with temperature sensitivity of -0.2878 nm/℃.Meanwhile,the sensitivity of the unpacked taper microfiber sensor is -0.0297 nm/℃,which is only one-tenth of the sensitivity of the packaged sensor.At the same time,the experiment verifies that the temperature sensitivity is little affected by the concentration of BN dispersion.The encapsulated sensor can protect the microfiber from the influence of impurities in the environment and the deformation caused by external forces to improve the stability of the sensor,and this sensor has a broad development prospect in the field of temperature sensing.(2)A miniature Fabry-Perot interferometer temperature sensing probe composed of capillary and agar film is designed and fabricated.The effects of capillary length and agar concentration on the performance of the sensor are studied.When the concentration of agar solution is constant,three kinds of capillaries with lengths of 0.08 mm,0.15 mm and 0.23 mm are selected for experiments.The corresponding wavelength drifts are 27.1 nm,11.9 nm and 3.7 nm,respectively.Then,when the capillary length is fixed,three concentrations of agar solution are selected,which are 2.4、1.4 and 0.5 wt%,respectively.The corresponding wavelength drifts are 51.8、44.1 and 19.4 nm,respectively.The experimental results show that when the concentration of agar solution is constant and the length of capillary tube is short,the response of the sensor to temperature is more obvious,when the length of capillary tube is constant and the concentration of agar is low.At the same time,the solid-liquid transition temperature of the sensor is about 40 ℃,which can be used as the boundary point for human body temperature detection.The sensor adapted to different requirements can be prepared by changing the capillary length and agar concentration.This sensor has good repeatability and stability possessing the certain application potential in the field of temperature sensing.