Fiber-optic gyroscopes with depolarized light

Experimental observations of π-bias phase shifts causing an inverted interference fringe have been made in fiber gyros using depolarized light and ordinary fiber. These observations are accounted for by a four-parameter birefringence model representing the gyro coil which explicitly accounts for polarization mode mixing in the interior of the coil. The addition of a Lyot depolarizer to the coil is shown to remove all birefringence-induced effects and to provide a constant scale factor