The embodiment of the invention provides a
multiplexing combined polarization-preserving
fiber ring implementation method and a polarization-preserving
fiber ring. In the implementation method, the two pigtails of an original polarization-preserving
fiber ring are respectively connected with the two
beam coupling pigtails of two polarizing
beam splitters / couplers (PBS) with polarization-preserving fiber pigtails, the two PBSes are connected by the one
branch pigtail of each PBS, and the other
branch pigtails of the PBSes are used as the two pigtails of the polarization-preserving
fiber ring after combination, wherein both the two
branch pigtails of each PBS are subject to slow-axis beam propagation and are respectively coupled with the slow axes or fast axes of the two
beam coupling pigtails, so that an incident
linearly polarized light wave sequentially and respectively circles round the
fast axis and the slow axis of the original polarization-preserving
fiber ring and then passes through the whole
fiber ring. By implementing the technical scheme, the two eigen polarization axes of the polarization-preserving fiber can be fully used, thereby lengthening the effective
optical path of the polarization-preserving fiber ring and effectively shortening the required fiber length under identical conditions.