Research On Temperature Sensing Characteristics Of MWFL Based On Vernier Effect

Multi-wavelength fiber laser(MWFL)-based sensors use light waves as sensing signals and optical fibers as transmission media to sense and detect external signals under test.They are compatible with sensing methods,sensing principles,and signal detection and processing.It has the advantages of simple structure,good compatibility with optical fiber systems,corrosion resistance,electromagnetic interference resistance and high response sensitivity.It has been widely used in structural health monitoring,aerospace and industrial production and other fields.In recent years,scientists have used the Vernier effect to increase the sensitivity of fiber optic sensors,which is:Using one interferometer as a vernier fixed scale and the other as a vernier sliding scale,by properly configuring two filters,it is easy to achieve several to dozens of times the sensitivity gain.Combining the filtering characteristics of Sagnac ring and FP(Fabry-Perot)interferometer,this paper designs two types of MWFL fiber optic temperature sensors based on the Vernier effect,and conducts detailed sensor model derivation and simulation analysis.Experimental test.The work of this article mainly includes the following four parts:(1)The first chapter introduces the research background and research objectives of the research topic,and then analyzes the latest research trends and application prospects of MWFL in the sensing field.Finally,the paper introduces the research and design of Vernier effect in MWFL sensor.(2)The second chapter introduces the application of filtering technology in multi-wavelength fiber lasers,including MWFL optical sensors based on different filter structures,Vernier effect generated by filter cascade and Vernier effect in MWFL sensing.Applications.(3)The third chapter analyzes the photonic devices that constitute the Vernier effect.Firstly,the filtering characteristics based on FP interferometer and MZ interferometer are analyzed and simulated.Then,the stress birefringence in birefringent fiber is simulated and the interferometer Sagnac interferometer and Lyot interferometer based on fiber birefringence effect are simulated.Finally,based on FP interferometer and Sagnac interferometer,the Vernier effect of MWFL sensor is simulated and a temperature sensing model with gain factor of 8 is proposed.(4)In the fourth chapter,several MWFL temperature sensors were tested experimentally.Firstly,the MWFL temperature sensor built with the polarization-maintaining fiber Sagnac ring was tested,and the temperature sensitivity of 1.7nm/? was obtained.Then a test based on The MWFL temperature sensor of the fiber FP filter has a temperature sensitivity of 0.008 nm/?.Finally,the Vernier effect-based MWFL temperature sensor is tested.It shows that the Vernier effect is more than 6 times more sensitive than the MWFL temperature sensor,and the temperature sensitivity is over 10nm/?.