Polarization multiplexing system for overcoming crosstalk between two polarization channels caused by optical fiber PDL

Abstract

The invention provides a polarization multiplexing system for overcoming crosstalk between two polarization channels caused by an optical fiber PDL, and relates to the polarization multiplexing system which is characterized in that at the polarization multiplexing end, continuous light wave emitted by a distributed feedback laser DFB-LD is divided into two beams of light by a polarization-preserving coupler, wherein the first beam of light passes through an adjustable Faraday rotation piece, and the second beam of light passes through an optical fiber delay line formed by a polarization-preserving fiber PMF, so that coherence between the first and the second light beams can be eliminated; the first beam of light passes through a modulator and bears a first path of optical channel, and thesecond beam of light passes through the modulator and bears a second path of optical channel; and the two beams of light bearing the optical channels can complete multiplexing through the coupler andthen reaches the polarization demultiplexing end through a transmission link. The polarization multiplexing system for overcoming the crosstalk between the two polarization channels caused by the optical fiber PDL solves the problem that polarization signals at the demultiplexing end are influenced by PDL effect in a transmission optical fiber link and are no longer in orthogonality, leads the polarization signals received by the demultiplexing end to be orthogonal by a feedback control system, and eliminates the influence of the PDL in the transmission optical fiber link.

Description

technical field [0001] The invention relates to a polarization multiplexing system, in particular to a polarization multiplexing system which overcomes the crosstalk between two polarization channels caused by optical fiber PDL. Background technique [0002] In the working mode of the polarization multiplexing system, when a wavelength is transmitted in the optical fiber, it carries two orthogonally polarized optical signals, which doubles the amount of information carried by the light under the condition of one wavelength. This polarization multiplexing technology can expand the communication capacity of the system on the basis of the existing wavelength division multiplexing (WDM) system, and reduce the expansion cost. [0003] Because the optical fiber is susceptible to the birefringence effect caused by the external environment, and the birefringent axis of the optical fiber will change randomly with time, after the two orthogonally polarized signals incident on the pola...

AI Technical Summary

Problems solved by technology

[0003] Since the optical fiber is susceptible to the birefringence effect caused by the external environment, and the birefringent axis of the optical fiber will change randomly with time, after the two orthogonally polarized signals incident on the polarization multiplexing end are transmitted through the optical fiber, the orthogonal polarization of the two polarized signals The polarity will be affected by the polarization dependent loss (PDL) of the fiber and will no longer maintain orthogonality at the polarization demultiplexing end, causing crosstalk between the two polarization signals and increasing the difficulty of polarization demultiplexing

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