Research On Temperature Sensing Characteristics Of Few Mode Fiber Dual Microcavity Based On Vernier Effect

As a common physical quantity,the monitoring and control of temperature is very important.Traditional temperature sensors such as thermistors and thermocouples will be greatly limited in some situations such as high temperature and high pressure,flammable and explosive,and strong electromagnetic field interference.Compared with the traditional sensor,the fiber sensor has the advantages of strong anti-interference ability,light weight and small size.The fiber Fabry-Perot(F-P)sensor has a simple and compact structure,and the combination of F-P sensing and the vernier effect can significantly improve the sensitivity,which can meet the needs of high-precision measurement in special environments.In this paper,the research status of existing F-P sensors and vernier effect sensors is extensively investigated.Based on the existing research,three dual-microcavity vernier effect temperature sensors with different structures are prepared,and their transmission characteristics and sensing characteristics are analyzed.The main research contents are as follows.Firstly,the basic principle of microcavity F-P interference is introduced,the transmission characteristics of multi-beam interference are discussed,and the sensing principle of the vernier effect fiber sensor is analyzed in detail.Secondly,the sensitivity-enhanced temperature sensor with end-coated Polydimethylsiloxane(PDMS)in few mode fiber(FMF)based on vernier effect was studied and fabricated,the theoretical model of the dual-microcavity vernier effect fiber sensor was established,the sensing principle of the sensor with this structure is analyzed.The sensing characteristics of the sensor of this structure are simulated.The transmission spectrum and temperature sensing characteristics of the sensor under different microcavity lengths were investigated experimentally.Thirdly,the FMF temperature sensor filled with PDMS based on vernier effect was researched and fabricated.,the theoretical model of the sensor was established,the sensing principle of the sensor was analyzed.Its sensing characteristics were simulated,and the sensor sensing performance of different structural parameters is explored through experiments.Finally,the parallel FMF dual-microcavity temperature sensor is researched and fabricated,the theoretical model of the parallel F-P sensor is established,the sensing principle of the parallel structure sensor is analyzed.And the sensing characteristics of the sensor with different structural parameters are simulated.The sensing performance of sensors with different structural parameters are explored.