Effective suppression of residual coherent phase error in a dual-polarization fiber optic gyroscope

The impact of residual coherent phase error in a dual-polarization interferometric fiber optic gyroscope (IFOG) is investigated. Although it has been intuitively assumed that the coherence of a light source can be eliminated by a sufficient long fiber delay, the experiment and theory indicate that it still contributes a remarkable portion to long-term instability. After the residual coherent phase error is well handled, we demonstrate a dual-polarization IFOG with bias instability of 3.56×10^-4°/h. Comparisons show that such performance is even better than the conventional "minimal scheme" that operates on one polarization.