Design And Test Of Photonic Devices For Microwave Photonic Temperature Sensing

Optical fiber sensing technology is a key technology in the current society,and it is widely used in temperature monitoring,stress monitoring and other fields.There are many types of optical fiber sensing technologies,but most of them are based on direct measurement of optical quantities for sensing.Microwave photonics has been extensively studied in recent years,and the use of microwave photonic filter methods to complete optical sensing is a new method developed in recent years.Combining microwave signals with optical signals for temperature sensing can achieve higher resolution.In order to improve the sensitivity of optical fiber sensing technology and understand the factors affecting the performance of microwave photonic filters,a series of theoretical and experimental research work has been carried out.This thesis tests the performance of microwave photonic filters under different light sources,and discovers the problem of the resonance frequency drift of narrow linewidth light sources,establishes a theoretical model of microwave photonic filter devices,and applies microwave photonic filters in three fields,and conducts in-depth theoretical analysis and experimental research.The main research results are summarized as follows:By studying the performance comparison of microwave photonic filters under different light sources,it is found that there is a lot of noise in the results of microwave photonic filters under coherent light sources.In order to explore the laser resonance frequency drift,this research uses the optical heterodyne method to design an experimental structure,and through experimental testing and analysis,the resonance frequency drift of the narrow linewidth light source is 5.149 MHz,22.956 MHz and 18.254 MHz respectively.According to the structure of the microwave photonic filter,the theoretical model of the electro-optical modulator and Mach-Zehnder interferometer under the condition of coherent light source and incoherent light source is established.The electro-optical modulator is used as the modulation part of the microwave photon filter,and the Mach-Zehnder interferometer is used as the interferometer part.These theoretical models are brought into the mathematical model of microwave photon sensing.According to the design principle and theoretical model analysis of the microwave photonic filter,it is applied to different scenarios to realize the recognition of the type of optical fiber connector,temperature detection and liquid detection on the optical fiber connector.The minimum value comparison method,maximum value comparison method and notch depth comparison method are used to process the optical fiber connector type identification experimental data.The microwave photonic filter composed of 3m-APC fiber has a deeper notch depth,and the microwave photonic filter formed by adding the 3m-APC fiber to the MZI interferometer is used for temperature sensing,and the sensing sensitivity can reach 0.179dB/°C.It can be seen that the microwave photonic filter can be used for fiber optic connector detection,temperature sensing,and fiber optic connector liquid type identification.The performance of microwave photonic filters is closely related to the parameters of optical devices such as couplers,light sources,and optical fibers,and this research provides theoretical and experimental basis for microwave photonic filters to be used in temperature sensing,liquid identification and other fields.