Increase in the correlation length of nonmonochromatic radiation during propagation in a single-mode optical fiber containing random inhomogeneities and the influence of this increase on the operation of a fiber ring interferometer

An analysis is made of the conditions under which the coupling of orthogona l polarization modes at random inhomogeneities in single-mode optical fiber s leads to an increase in the correlation length of a source of nonmonochro matic radiation. It is shown that when long-base fiber ring interferometers with a single-mode fiber ring system possessing weak linear birefringence are used, the correlation length of the nonmonochromatic radiation at the i nterferometer exit is increased, which means that the interference pattern can have satisfactory visibility even when there is an appreciable differen ce between the interferometer arms as a result of the Sagnac effect due to the Earth's rotation. The calculations were made by mathematical modeling o f random inhomogeneities in the fiber. (C) 1999 American Institute of Physi cs. [S1063-7842(99)03107-4].