Magnetic field error in twin depolarized interferometric fiber optic gyroscopes induced by vertical magnetic field

•An error will be induced in TD-IFOGs in the axial magnetic field.•The error comes from the fiber’s bending.•As to a TD-IFOG manufactured, the error is linear to the axial magnetic field.

We put forward a theory that the magnetic field vertical to the sensing coil plane may induce a nonreciprocal phase error (NPE) in twin depolarized interferometric fiber optic gyroscopes (TD-IFOGs). A related mathematical model is established. The simulation analysis and experimental result show that the magnetic field error induced by a vertical magnetic field in a TD-IFOG is relatively stable. The error arising from the bending of the fiber is closely related with the radius of an optical fiber coil, fiber’s diameter, fiber’s length, the strength of the vertical magnetic field and so on. And as for a manufactured TD-IFOG, the vertical magnetic error is proportional to the magnitude of the vertical magnetic field.