Study Of Sapphire Fiber Optic Fabry-perot Contact High Temperature Sensor Based On Wafer Type Microcavity

Temperature measurement is one of the main application areas of optical fiber sensing technology,and high temperature measurement has always been one of the difficulties in the field of temperature measurement.Traditional high temperature sensors are mainly made of platinum-rhodium,tungsten-rhenium thermocouple materials,but the long-term reliability of the thermocouple is poor and the cost is high.It can not be used in harsh environments such as strong electromagnetic interference and strong radiation.More than a decade ago,some scholars proposed to fabricate sensors with sapphire optical fibers with good high temperature characteristics.However,in high temperature environment,the temperature range is often large,so it is necessary to fabricate sensors with long temperature range.In addition,free particles are easy to contaminate the optical sensor probe at high temperature.Therefore,it is necessary to study long-term and reliable preparation methods and packaging methods in order to make sapphire fiber optic high temperature sensor practical.Based on fiber optic sensing technology,this paper studies a new sapphire fiber Fabry-Perot sensor that can be used for long-term high temperature resistance and can realize direct contact measurement with sapphire fiber and micro sapphire wafer as the main material.The specific work is as follows:(1)This paper introduces the background and significance of the direct measurement of contact sapphire fiber Fabry-Perot high temperature sensor,analyzes the development history of fiber optic high temperature sensing technology,focuses on the development of sapphire fiber high temperature sensing technology,and puts forward the research focus and innovation.(2)The principle and demodulation method of sapphire high temperature Fabry-Perot sensing technology are introduced.Several demodulation methods suitable for Fabry-Perot sensor are discussed.The requirement of wafer thickness for forming a Fabry-Perot micro-optical cavity using two parallel faces before and after the micro sapphire wafer was studied.(3)The design and upgrade of the sapphire fiber Fabry-Perot sensing system used in this project are introduced.The selection of the length and diameter of the sapphire bare fiber and the improvement of grinding,process,sapphire fiber and wafer packaging are discussed.Mode field matching between multimode fiber and sapphire bare fiber,and successful implementation of low loss fusion between multimode fiber and sapphire bare fiber.(4)Long-distance transmission of optical signals with low loss using sapphire fiber is realized.The overall package of the sensor was completed,and an improved sapphire fiber Fabry-Perot high temperature sensor was fabricated.The experimental research and application in related fields were carried out.By comparing the sensor in the laboratory environment,the high temperature measurement capability of this type of sensor is verified by the stability and reliability of the industrial environment and simulated aerospace environment.Experiments show that the sensor can be inserted into high temperature objects such as high temperature furnaces to achieve direct contact measurement depth more than 1m,accurate temperature measurement in the temperature range of 25-1100?,temperature measurement accuracy is stable at ±2.5?.It has broad application prospects in the fields of high temperature measurement,such as scientific research,industry,and national defense.