| At present,fiber optic gyroscope(FOG)as positioning and navigation has been widely used in military,aerospace,navigation and other aspects.The upgrade of FOG is moving towards miniaturization,light weight and high performance,which is conducive to the improvement of various performance indicators of the navigation system.However,the research of polarization maintaining fiber(PMF)polarizer,the core component of FOG,is particularly important.At present,the ultra-fine PMF is gradually replacing the currently used PMF.It has the advantages of light weight,small size and small stiffness,which is conducive to the miniaturization and lightweight reconstruction of FOG.However,its disadvantages are that the material is brittle and easy to break,and it is difficult to make devices.therefore,the difficulty hindering the research of polarizers for ultra-fine PMF is that the orientation of the polarization axis of ultra-fine PMF cannot be identified without damage.This paper conducts research based on the on-line alignment technology of ultra-fine PMF and the manufacture of polarizers.First,in order to solve the difficulty of identifying the polarization axis of the ultra-fine PMF without damage,the forward-scattered light field formed by the laser irradiation of the ultra-fine PMF is optically simulated,and the light field that changes with the direction of the polarization axis is obtained.Two candidate eigenvalues reflecting the orientation of the polarization axis of the ultra-fine PMF are obtained from the characteristic curve,namely the main peak and the width center of the wide peak.Subsequently,the forward scattering experiment of the ultra-fine PMF was designed,and the experimental results were found to be similar to the theoretical simulation results.However,the main peak of the characteristic curve was used as the characteristic value to identify the orientation of the polarization axis of the ultra-fine PMF,which has a large error and cannot be applied,and the width center of the wide peak in the characteristic curve is suitable for its alignment.To further determine the feasibility of this eigenvalue,an end-face experiment based on forward scattering of ultra-fine PMF was designed.The distribution of the stress area on the end face of the fiber and the results of the image processing of the scattering fringe were compared,and the feasibility of this eigenvalue was confirmed,the accuracy of its alignment is within 1.2°.Therefore,the width center of the wide peak in the characteristic curve is determined as the eigenvalue of the ultra-fine PMF for alignment,and the method of alignment is called the wide-peak eigenvalue method of the forward-scattered image for the ultra-fine PMF.After that,the first commercial Online and intelligent alignment equipment based on the ultra-fine PMF and supporting application software were designed and manufactured,and an automatic non-destructive automatic axis-alignment of ultra-fine PMF was realized.Finally,the ultra-fine PMF polarizer was developed by the side polishing coating method,and several ultra-fine PMF polarizers were successfully manufactured,their polarization degree and extinction ratio were tested.The test results show that all polarizers can be polarized,the degree of polarization is above 90%,the extinction ratio is above 15 dB,and the optimal is 31.73 dB.Compared with the currently used polarizers,its performance is more superior.The innovation of this paper is to develop a wide-peak eigenvalue method of the forward-scattered image suitable for on-line and damage-free alignment of ultra-fine PMF,and design and manufacture the first Online and intelligent alignment equipment based on the commercial ultra-fine PMF,And based on this,the first ultra-fine PMF polarizer was successfully produced. |
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