Polarization-Tracking-Free PDM Supporting Hybrid Digital-Analog Transport for Fixed-Mobile Systems

For fixed services such as hybrid fiber-coaxial and passive optical network with deployed fiber networks, it is desirable to exploit the potentials to support wireless services in fifth-generation (5G) mobile data communications on the top of the existing fixed networks. We propose a polarization-division multiplexing (PDM) scheme to achieve the co-delivery of independent signals for fixed-mobile convergence. This is achieved by removing unwanted optical carrier in each polarization, and thus the proposed system can resolve the polarization-tracking issue in conventional PDM. It has been demonstrated in this letter that the polarization-tracking-free PDM system can support the co-transmission of respective 70-Gbps digital and analog signals over 20-km single mode fiber. Experimental results have shown low crosstalk between two polarizations. The proposed PDM system is compatible with wavelength-division-multiplexing (WDM) network and is capable of enhancing the spectral efficiency of WDM channels. The inherent single-sideband feature of the proposed PDM also enhances long-range services.