Backscatter-induced noise and crosstalk in a FDM multidimensional gyro system using two bias modulators in each gyro loop

Characteristics of backscatter-induced noise and crosstalk in a multidimensional FDM fibre-optic gyro system, using two bias modulators in each gyro loop, are investigated. The induced noise is in the order of a few degree per hour for a 1 mm coherence length source and typical gyro parameters. The crosstalk is larger than the noise and increases with the number of gyros to be multiplexed. Both the noise and crosstalk can be reduced by using proper modulation depths and frequencies. The noise can also be eliminated by using 50/50 loop couplers.