Wavelength Correlation Detection and Third Closed-Loop Compensation for Enhancing Fiber-Optic Gyroscope Scale Factor Stability

The scale factor of fiber-optic gyroscopes (FOGs) is influenced by the central wavelength of the light source, with variations in wavelength affecting its stability. This article examines the correlation between ramp-reset-induced light intensity errors and central wavelength under overmodulation, leveraging the coherence properties of a broadband light source. A novel demodulation method is proposed to demodulate ramp-reset-induced light intensity errors, enabling wavelength correlation detection and third closed-loop control through phase compensation. To reduce the scale factor’s dependency on wavelength variations, a wavelength-compensation phase model is proposed. Furthermore, we develop a compensation phase-scale factor model that correlates compensated phases with the scale factor across different temperatures, thereby enhancing scale factor stability. Experimental results demonstrate that, within the temperature range from $- 45~^{\circ }$ C to $65~^{\circ }$ C, scale factor variation is reduced from 1028.00 to 688.41 ppm using the first-order wavelength-compensation phase model, and further reduced to 354.71 ppm with the second-order compensation phase-scale factor model.