Research On Testing Methods For Polarization Maintaining Fiber And Fiber Loop Of Fiber Optic Gyroscope

Fiber optical gyroscope (FOG) is one kind of inertial equipments based on sagnac effect. It becomes more and more popular in inertial and navigation field because of the advantages such as high reliability, long working life and large dynamic range and so on while compared with the traditional gyroscopes. One of the reasons why the precision of the FOG in our country is still lower than that in some developed countries is due to the limitation of fiber loop of FOG.The principle and structure of polarization maintaining fiber (PMF) are introduced firstly. Based on the analysis of fiber enwinding, we get the conclusions as follows: induced birefringence that will be generated by the deformation produced by bending and torsion stress affect the intrinsic birefringence of PMF. And the simulation of the two kinds of induced birefringence of deformation is described in the paper.In order to know more about the birefringence of PMF, we give the thermodynamic simulation of panda-type PMF using ANSYS software. The result shows that the precision would be affected greatly by cross-coupling while the temperature becomes higher.The examples of inner fiber loop including thermal stress and birefringence variation are analyzed while coating adhesive or not, and it behaves better for induced birefringence of fiber loop caused by temperature after coating adhesive. The simulation of temperature experiment indicates that the instability of FOG would be induced by the temperature difference.At last, one detecting method is designed to test the performance of fiber loop for temperature. Through some different fiber loop tests, we get the conclusions that the temperature stability would decrease greatly because of asymmetricof the coating adhesive. And this result gives us useful reference for the detector of FOG fiber loop.