Mechanism analysis and suppression method of mode hopping in high-precision interferometer fiber optic gyroscopes under large angular acceleration

High-precision interferometer fiber optic gyroscopes (I-FOG) always employ fiber coil with long length and large diameter, which then results in a small optical measurement range. In order to enlarge its measurement range, cross-stripe technology and over-range saturated output technology are usually adopted. When the input angular acceleration exceeds the response capacity of I-FOG, the mode hopping phenomenon, which is caused by the insufficient ability of angular acceleration resistance of I-FOG and exhibits as $\phi_{\boldsymbol{s}1}\pm 2\boldsymbol{k}\pi (>\phi_{\boldsymbol{s}1}$ is the actual response value, $k=1,2,3\ldots$), usually occurs. In this paper, the mechanism of mode hopping fault is theoretically analyzed. Subsequently, a number of methods such as the structural optimization to reduce translation-rotating coupling, increasing the response bandwidth and using external reset signal, are proposed. Experiments show that the angular acceleration resistance ability of I-FOG is improved to 220000 deg/s2 from 80000 deg/s2, which greatly improves the reliability of high-precision I-FOG under large angular acceleration.