We have investigated the amplitude variation effects in a serrodyne fiber-optic gyroscope (FOG). As the results of numerical calculation, it became clear that there are bias, scale factor error and discontinuity in regard to the linear relationship between serrodyne frequency and sagnac phase shift. And we confirmed those errors experimentally.
"Amplitude Variation Effects Of Phase Modulators In A Serrodyne Fiber-Optic Gyroscope", Proc. SPIE 1169, Fiber Optic and Laser Sensors VII, (13 February 1990); doi: 10.1117/12.963049; https://doi.org/10.1117/12.963049