Analysis of the Influence of Residual Intensity Modulation in the Multifunction Integrated Optic Circuit on Fiber-Optic Gyroscopes Performance

The residual intensity modulation (RIM) of the multifunction integrated optic circuit (MIOC) can be classified into the linear term and the nonlinear term, which can impact the performance of the fiber-optic gyroscope (FOG). According to the generation mechanism of the RIM and the demodulation principle of the FOG, a model is established to analyze the influence of RIM on the FOG performance. Simulation shows that both the linear and the nonlinear RIM can lead to a large and sudden change in the FOG output at reset points of the feedback step wave, as well as fluctuations within the reset period. The magnitude of the sudden change at the reset point is proportional to the difference between the linear RIMs of two branches in the MIOC, and the fluctuation within the period of the feedback step wave is more dependent on the nonlinear RIM. The relationship between the FOG output and the linear and nonlinear RIMs are verified by experiments. The RIM-induced output can result in the increase of the bias error and the scale factor error of the FOG, especially at small input angular velocity. Furthermore, the application of FOG for the real-time high-speed position tracking to stabilize the attitude control platform can be limited.