General formula describing drift of interferometer fiber-optic gyro due to Faraday effect: reduction of the drift in twin-depo-I-FOG

The drift of an interferometric fiber-optic gyro (I-FOG) by the magnetic field through the Faraday effect is generally formulated. By the derived formula, the drift reduction mechanism in the interferometric fiber-optic gyro using ordinary single-mode fiber as a sensing coil and two depolarizers (twin-depo-I-FOG) is clarified, as well as that in the interferometric fiber-optic gyro using polarization maintaining fiber (PM-I-FOG). Degradation factors in the practical twin-depo-I-FOG are evaluated by using the derived equation, and methods for further drift reduction are discussed.