An investigation of polarization nonreciprocity’s effect on the performance of scale factor in closed-loop fiber optical gyroscope

The performance of scale factor is generally thought to be just dependent on the stability of wavelength, the area of fiber coil, and half-wave voltage of modulator, but its dependence on polarization nonreciprocity (PNR) in a closed-loop fiber optical gyroscope (FOG) is investigated here theoretically and experimentally. A model is established to obtain the primary waves and the main secondary waves existing in the FOG, based on which their interference intensities are obtained and utilized for closing loop. The simulation result reveals that a bias error caused by PNR depends on input angle velocity, so scale factor error arises as a result. The phase difference between the primary and secondary waves, which is induced by different optical paths they have experienced in birefringent segments, affects PNR’s contribution to scale factor error and may make PNR cause large nonlinearity of scale factor, even “dead zone” under small input angle velocity. The experiment verifies the analyzing and simulation results.