Fiber-optic gyroscopes with broad-band sources

The use of broad-band sources, polarized and unpolarized, in fiber gyroscopes with linearly birefringent fibers, is studied theoretically. Polarization-mode coupling in the fiber is modeled using one-mode coupling center. Gyroscope output equations are obtained which are useful in interpreting an origin of fiber noise in the limiting cases of low and high fiber birefringence. Interference effects in the output are shown to be related to mode coupling at particular locations in the fiber. The extent of these locations is governed by a depolarization length for which numerical estimates are given.