This paper analyses on the effect of coherent backscatter on the output of the fibre optic gyroscope. By considering the phases and modulation efficiency of the backscatter beams, the analysis shows that Inertial Navigation performance should be able to be achieved by using relatively long coherence length sources, thus easing source wavelength stabilisation. The fundamental limit to the backscatter noise is shown to be due to the scattered components which are incoherent with the primary beams. The effect of the components which are coherent with the primary beams can be eliminated by use of the correct modulation frequency or polarisation control and tuning of the loop coupler.
J. M. Mackintosh,
J. L. McMillan,
"Coherent Backscatter In The Phase-Modulated Fibre Optic Gyroscope", Proc. SPIE 0630, Fibre Optics '86, (6 October 1986); doi: 10.1117/12.963607; https://doi.org/10.1117/12.963607