A phase modulation method for improving the scale factor stability of Fiber-Optic Gyroscope

The usual scheme of fiber-optic gyroscope(FOG) is digital single closed-loop, but the scale factor stability is affected by the variation of half-wave voltage of LiNbO₃ integrated optic phase modulator. The half-wave voltage changes with the variation of the integrated optic phase modulator performance dependence on temperature and the bias voltage applied to the phase modulator. In order to improve the scale factor stability, double closed-loop scheme FOG with square wave biasbias modulation is used to compensate the the variation of half-wave voltage, but it is inefficient at low rates. The double closed-loop scheme FOG with ldquofour-bias-staterdquo bias modulation is used to improve the compensation efficiency and SNR, and the bias modulation equations are presented here. The scale factor stability of the new scheme is improved about by one time than the usual scheme.