| Nowadays,with the rapid development of military science and technology,positioning system is widely used in the fields of precision guidance system and manned space engineering.Interferometric fiber optic gyroscope(IFOG)has been widely used in these fields due to its advantages of high precision and small size.Y-Waveguide and optical fiber ring are the core polarization maintaining devices of interferometric fiber optic gyroscope.Their polarization performance directly affects the zero drift and random walk coefficient of fiber optic gyroscope.Facing the demand of mass production and rapid development of precision fiber optic gyroscope,it is necessary to test and analyze the polarization characteristics of polarization maintaining device in batch.Optical coherence domain polarization measurement technology has the advantages of large dynamic range,high sensitivity,long measurement distance and so on,but when batch testing polarization maintaining devices,analyzing the polarization characteristics of polarization maintaining devices will consume a lot of manpower.Therefore,based on the polarization measurement technology in the optical coherence domain,this thesis has carried out relevant research on the shortcomings of batch measurement of the polarization characteristics of Y-Waveguide and optical fiber ring.The main work is as follows:(1)Aiming at the problem of low efficiency of accurately identifying and extracting the coupling information peak of Y-Waveguide,this thesis studies the peak extraction method of Y-Waveguide coupling information peak based on optical path tracking method.An algorithm is proposed to accurately identify the position and amplitude of the coupling information peak by iteratively verifying the coupling superposition relationship between the first-order coupling peak and the second-order coupling peak of Y-Waveguide.This method can solve the problem of identifying the interference superposition of the first-order coupling peak and the position overlap of some second-order coupling peaks;(2)Aiming at the problem of low accuracy in quantitative analysis of polarization periodicity characteristics of optical fiber ring,this thesis improves the extraction method of layer change peak characteristics,turn change peak characteristics and fiber noise background characteristics of optical fiber ring based on frequency domain analysis.According to the periodic winding structure of the optical fiber ring,the parameters of the frequency domain adaptive filter are designed,and the energy integration method is used to calculate the lumped extinction ratio of the optical fiber ring,so as to realize the quantitative analysis of the polarization characteristic parameters such as the average crosstalk value of the layer change peak,the average crosstalk value of the turn change peak,the fiber noise background,and the lumped extinction ratio of the optical fiber ring;(3)The automatic analysis software for polarization characteristics of Y-Waveguide and optical fiber ring is designed,which realizes the identification and extraction function of polarization characteristics evaluation parameters of polarization maintaining device,and improves the analysis efficiency of test data.The polarization characteristics of Y-Waveguide and optical fiber ring were tested at room temperature and variable temperature.The polarization characteristics and temperature fluctuation characteristics of polarization maintaining device were analyzed and evaluated by using automatic analysis software.In this thesis,a method of extracting the polarization periodic characteristics of the Y-Waveguide coupling information peak and the optical fiber ring is proposed,and an automatic analysis software of polarization characteristics is developed,which can solve the problems of low efficiency of identifying and extracting the Y-Waveguide coupling information peak and low accuracy of quantitative analysis of the periodic characteristics of the optical fiber ring.The research work of this thesis provides an analytical means for the quantitative evaluation of polarization characteristics of polarization maintaining devices,and provides technical support for the improvement of the manufacturing process of polarization maintaining devices. |
