Polarization Demultiplexing Technologies In Stokes Space

With the large-scale development of cloud computing and big data in recent years, people’s demand for transmission rate and bandwidth are growing rapidly. High large and large capacity optical fiber communication technology would become the most promising candidate for meeting the ever-growing data traffic.Polarization division multiplexing (PDM) systems with two polarization (SOPs) over one wavelength can double the spectral efficiency directly without additional bandwidth resources. At the same time, PDM can combine with novel modulation format and coherent detection techniques, which can achieve polarization demultiplexing and compensate for transmission impairments by employing the DPS at the receiver side. PDM technique has been emerging as one of the key techniques for next high speed and long haul optical fiber communication system. However, as for high speed and short reach optical fiber communication systems, intensity modulation and direct detection (IM/DD) is considered as a competitive candidate due to the low cost and simple implementation. Therefore, polarization demultiplexing technology based on IM/DD may be desired. As the SOPs of signal can be intuitively and specifically represents in the Stokes space, polarization demultiplexing can achieved in the Stokes space. In this work, a polarization demultiplexing and signal distortion compensation scheme based on Stokes vector analysis for IM/DD short reach PDM transmission system is proposed and numerically and experimentally investigated. The main works are listed as following:Firstly, the configuration and key components of PDM system are briefly introduced. Meanwhile, some impairments in PDM systems, such as chromatic dispersion (CD) and polarization mode dispersion (PMD), are analyzed as well. Based on that, a low cost and complexity polarization demultiplexing scheme based on Stokes vector analysis for IM/DD PMD system are proposed.Then, an IM/DD PDM optical communication system is built based on the VPItransmissionMakerTM software platform for verifying the feasibility of the method. The demultiplexing performance comparison is carried out between the traditional Stokes vector analysis method and our simplified Stokes vector analysis method. The effect of the chromatic dispersion (CD), polarization mode dispersion (PMD) and polarization dependent loss (PDL) on the demultiplexing performance are also well investigated. All the simulation results show that the influence of PMD and PDL in the short-reach (e.g.10km or 25km SMF link) IM/DD PDM are negligible.Finally, a 20 Gbit/s single polarization system and 2×10 Gbit/s polarization multiplexing system are set up. The performance of the simplified stokes vector scheme with different transmission distances (i.e. back to back,10-km,25-km) is tested and verified. Experiment results and show that, compared with single polarization system,the power penalties of polarization multiplexing system in different transmission distances are only 0.3-dB、0.2-dB、0.2-dB respectively (@BER of 10-4). And in polarization multiplexing system, only 1-dB and 1.7-dB power penalties are measured for 10-km and 25-km transmissions compared to back-to-back case (@BER of 10-4).