The Influence and Suppression of Spectral Width on Scale Factor Nonlinearity in Fiber Optic Gyroscopes with Broadband Sources

Accurate measurement of rotation rates is crucial for fiber optic gyroscopes (FOGs), and ensuring the linearity of the scale factor is essential. However, the spectral width of the light source causes the interference curve of the fiber optic gyroscope to exhibit non-periodic attenuation. In closed-loop gain control FOGs, this aperiodic characteristic introduces light intensity errors during the reset time of the feedback signal, affecting the scale factor nonlinearity. This paper analyzes the influence of the spectral width of a Gaussian source on the interference intensity curve of FOGs. The relationship between spectral width, modulation depth, and ramp-reset-induced light intensity errors is investigated. Simulation results indicate that the scale factor nonlinearity of FOG deteriorates with an increase in spectral width, as well as modulation depth. To mitigate these effects, a symmetric reset method is proposed, ensuring that the phase difference at ramp-reset time remains within the same order fringe. Experimental results demonstrate that when the phase difference operates on the zero-order interference fringe, a remarkable 37.39-fold improvement in the scale factor nonlinearity of the fiber optic gyroscope with the implementation of the symmetric reset method compared to the conventional method.