Theory And Technical Research Of IFOGs Using Polarization Maintaining Optical Circulator

A gyroscope is an instrument used to measure the angular rate or angular displacement of a certain object. It’s of significant value as it’s the key part in inertial navigation and inertial detection systems. Among the various kinds of gyroscopes, fiber optic gyroscope(FOG) has always been a research hotspot due to its excellent performance. Additionally, interferometric fiber-optic gyroscope(IFOG) is the kind of FOG with the most complete theory system and the most mature technology at present.Conventional IFOGs use optical coupler as the connector of its light path, which causes energy loss and damage to the stability and service life due to return light into the SLD. So now optical circulator has been used to replace the optical coupler. However, conventional optical circulator brings new trouble because of its unsymmetrical light path and serious polarization coupling. Considering that the IFOGs use just one polarization state of the light, the polarization maintaining optical circulators have been invented, which solves the above problem.This article studies the polarization maintaining optical circulator. Firstly, we build a mathematical model for it to explain the reason why it may improve the performance of the IFOG. We give the theoretical value of the bias stability of the PM-IFOGs using it. Secondly, we build up a performance index system of it and gives its testing method. At last, we conduct an experiment to compare IFOGs using optical couplers and IFOGs using the polarization maintaining optical circulators. We find that the polarization maintaining optical circulators improve the performance of the IFOGs greatly.