Excess relative intensity noise suppression in depolarized interferometric fiber optic gyroscopes

Abstract

Excess relative intensity noise (excess RIN) is one of the major factors that degrade the short-term performance of interferometric fiber optic gyroscopes (IFOGs). We theoretically and experimentally investigate the correlation of excess RIN between interferometric and reference signals in depolarized IFOGs in which single-mode fiber coils are adopted to make them cost-effective. The Lyot depolarizers decrease the correlation coefficient to about 81%, giving a lower limit that excess RIN can be suppressed to 59%. Then, an excess RIN suppression method by co-processing interferometric and reference signals electronically is proposed that works well with the open-loop demodulation. Experimental results show the proposed method compensates the excess RIN to 60.4% compared to original, almost achieve the noise limit of the depolarized configuration.