Nonlinear Fourier transform for dual-polarization optical communication system

New services and applications are causing an exponential increase in the internet traffic. In a few years, the current fiber-optic communication system infrastructure will not be able to meet this demand because fiber nonlinearity dramatically limits the information transmission rate. Eigenvalue communication is considered an emerging paradigm in fiber-optic communications that could potentially overcome these limitations. It relies on a mathematical technique called “inverse scattering transform” or “nonlinear Fourier transform (NFT)” to exploit the “hidden” linearity of the nonlinear Schrödinger equation as the master model for signal propagation in an optical fiber. One of the rapidly evolving NFT-based communication techniques is called nonlinear frequency division multiplexing (NFDM). Being still in its infancy, NFDM systems still have some practical limitations. One of these limitations is the lack of polarization division multiplexing. This thesis addresses this problem by introducing the novel concept of dual-polarization NFDM. First, the structure of a single polarization NFDM system using the discrete nonlinear spectrum is described. The particular design aspects of this system are then discussed in details. Afterwards, the theoretical tools that define the NFT for the Manakov system,which describes the evolution of a dual polarization signal in a single-mode fiber, are presented. Using these tools the discrete NFDM system is extended to the dual polarization case. Finally, the results of the first experimental transmission of a dual polarization NFDM system are presented. A transmission of up to 373.5km with bit error rate smaller than the hard-decision forward error correction threshold has been achieved. The results presented demonstrate that dual-polarization NFT can work in practice and that it enables an increased spectral efficiency in NFT-based communication systems, which are currently based on single polarization channels