Deep phase-modulation approach to an open-loop fiber optic gyroscope

A new approach to an open-loop, all-fiber gyroscope with a wide dynamic range and linear scale factor is described. For signal processing, the Sagnac phase lift is converted into a phase shift in the low-frequency electrical signal by using a deep sinusoidal phase-modulation waveform followed by gate switching. With the duty cycle of the gating signal selected to be in the range between 20 and 70%, the scale factor is stable with respect to change in the amplitude of the phase modulation signal by as much as 15%. The basic principle of the technique and experimental results are reported.>