Effect of highly birefringence fibers on fiber optic gyroscope

Abstract

The fiber optic gyroscope (FOG) is a solid-state rotation sensor which is currently employed in inertial navigation systems. Highly birefringence fibers can be used to as polarization-maintaining (PM) fiber in FOG. PM fibers can reduce both the drift polarization cross coupling created polarizer and drift due to the earth's magnetic field via the Faraday Effect. But when the two beams polarized along fast and slow axes traverse the PM fiber, interference between the two counter-propagating beams may be influenced by the dispersive nature of the modal birefringence. The modulus of the degree of coherence, |γ| with respect to the interference between the two orthogonally polarized waves, may impose a severe restriction on the phase difference detection. Hence the problem of the signal to noise radio with respect to the received signal may be strongly influenced by the modulus of the degree of coherence. In this paper interference between two orthogonally polarized modes traversing a highly birefringence fiber is investigated theoretically and experimentally. Simulation results show that the detection sensitivity of fiber optic gyroscope employing highly birefringence fiber is degraded as the chromatic dispersion difference between the two mode increases. The result obtained here will provide useful data for the design and performance evaluation of fiber-optic sensors employing polarization-maintaining fibers.