The current state-of-the-art of the heterodyne scheme for fiber-optic gyroscopes is described. An emphasis is given to the fact that the heterodyne phase-detection scheme offers the remarkable advantage, such as stable scale factor, linearlity in the output of the rotation rate, and wide dynamic range of the measurement. Some typical heterodyne fiber-optic gyroscopes are explained. There are strong demands on developing a novel heterodyne fiber-optic gyroscope that can overcome technical difficulties.
"Optical Heterodyne-Detection Schemes For Fiber-Optic Gyroscopes", Proc. SPIE 0954, Optical Testing and Metrology II, (16 January 1989); doi: 10.1117/12.947641; https://doi.org/10.1117/12.947641