Theory of an amplified closed-Sagnac-loop interferometric fiber-optic gyroscope

An amplified closed-Sagnac loop interferometric fiber optic gyroscope (AC-I FOG) has been proposed and demonstrated in our earlier work. This paper rep orts the theoretical analysis of its operation. The analysis has been focus ed on the effect of the erbium-doped fiber amplifier (EDFA) inserted within the reentrant path. The analysis shows that the sensitivity can be improve d by at least two orders of magnitude as compared to a conventional IFOG if the EDFA is an ideal device, The simulated open-loop response coincides we ll with that of the experimental data. Further analysis shows that the dete ction limit is restricted by the beat noise that build ups rapidly in succe ssive circulations. The rate of noise build-up depends greatly on the optic al bandwidth of the closed-Sagnac loop.