Analysis and suppression of inter-axis optical crosstalk on threshold of multi-axis fiber optic gyroscopes

Multi-axis fiber optic gyroscopes (FOGs) commonly utilize a single superluminescent diode (SLD) light source to drive multiple optical paths, enabling compact design and reduced power consumption. However, internal backreflections within the shared SLD source can introduce inter-axis optical crosstalk, significantly degrading the accuracy of low rotation rate measurements. This paper investigates the mechanism of backreflection at the fiber end face within the SLD source and constructs a model of inter-axis optical backreflection crosstalk pathways. A mathematical relationship is derived between the optical backreflection crosstalk and the closed-loop feedback phase of each axis. To quantitatively characterize crosstalk, an open-loop excitation method is proposed to measure the optical backreflection crosstalk coefficients experimentally. A closed-loop control model is then used to simulate how varying crosstalk coefficients influence the system's threshold. To mitigate this impact, a static operating point flipping bias method is introduced. Experimental results demonstrate that this method reduces the threshold from 0.2°/h to less than 0.01°/h, thereby substantially improving the low rotation rate measurement accuracy of multi-axis FOGs.