Research On Y Waveguide Properties In Fiber-optic Gyroscope's Performance

Y-waveguide is being used as polarizer, beam splitter and phase modulator more and more while the higher and higher demand of performance of FOG. Y waveguide has the advantage of high extinction ratio and wide bandwidth, and it causes the possibility to modulate the characteristic frequency of FOG. It is focused on the influence of the performance of FOG with the Y waveguide in order to get deeper theory analysis about FOG in this paper.It gives the basic theory of FOG and the introduction of Y waveguide. Through the comparison Y waveguide is proved to be the important device for the performance of FOG. Also the performance parameter of Y waveguide, related definition and method are described.The mathematic model is established based on the relationship between Y waveguide and FOG. We get the conclusions from the simulation and experiment of the mathematic model as follows: first, the unsatisfactory beam ratio has effect to the bias stability of FOG. Second, insertion loss and backscattering affect the performance of FOG. Third, polarization crosstalk has relationship with the bias stability of FOG while the variation of temperature. The existence of back reflection influence the phase error of optical gyro's output signal.?In addition, we design the corresponding test program to test performances, test results validate the theoretical derivation.For the electrical characteristics ,The conclusion that half-wave voltage is variable with the temperature from the theoretical analysis indicates that it would affect the scale factor of FOG. We give the advantages and disadvantages in the three testing course. Besides the above points, we also get some conclusions as follows: first, RIM residual strength has little influence to the bias stability of FOG but limit the stability of the scale factor. We design the RIM residual strength testing plan, and from the simulation we find one conclusion that the scale factor will change a lot even that RIM residual strength changes little while the phase is at positive +Ï€/ 2, and vice versa while the phase is at positive -Ï€/ 2. This effect for the high-precision digital closed-loop fiber optic gyroscope is can not be ignored. This discovery provides some theoretical guidance for further improve the accuracy of fiber optic gyroscope.