Study Of Optical Fiber High-temperature Sensor Based On Sapphire Wafer

As one of the seven basic units of System International(SI),temperature is a very important physical parameter to object.Measurement of temperature plays a significant role in the field of industrial production and scientific research,and has been highly valued by researchers.With the continuous development of science and technology,we have already obtained the ability to measure temperature under 1000 ? precisely.However,there are still many problems when measured temperature is above 1000?,either the accuracy is too low or the service life of the equipment is too short.On the other hand,in many application fields,such as metallurgy,energy,chemical industry and aerospace,there is still in urgent need of long-term,stable and precise measurement of temperature above 1000?.Therefore,a new type of high temperature sensor is essential.In this thesis,based on the research of Fabry-Perot(F-P)high-temperature sensors and sapphire fiber high temperature sensors,we designed and fabricated a noval high-temperature sensor of sapphire crystal optic fiber based on sapphire wafer.The main research contents and achievements of the paper are as follows:(1)We introduced several types of electrical temperature sensors,optical fiber temperature sensors and sapphire fiber high temperature sensors.After analysing the performance of different sensors,we decide to design a new type of high temperature sensor by combing advantages of sapphire fiber high temperature sensor and optic fiber F-P sensor.(2)We studied several related demodulation methods according to the structure and interference principle of fiber F-P sensor.We described the demodulation principles of these methods and pointed out their advantages and applicable scopes.To improve demodulation accuracy,we analysed the principle of extrinsic F-P interferometer in detail from the perspective of geometric optics and mode distribution,and obtained the accurate formula of interference.These work provide a theoretical basis for the signal processing and the later sensor production.(3)We studied the key preparation technologies of the fiber F-P high temperature sensor based on sapphire wafer,such as the polishing of sapphire fiber?the fusion welding of sapphire fiber and M-M optic fiber?the relatively fixation of sapphire fiber and sapphire wafer.These can increase the light intensity of the interference signal as well as improve the stability and the service life of the sensor.(4)We set up a high-temperature experimental platform,and analysed the performance of our sensor through experimental data.The results show that the sensor has the measurement range of 20-1500? and accuracy of ±2.5?.Stability and repeatability of obtained data are good.At the end of the paper,we put forward some suggestions and improve thinking on the further research of high temperature sensor.