Schemes integrating inter-carrier interference （ICI） self-cancellation and common phase error （CPE） com- pensation for coherent optical orthogonal frequency division multiplexing （CO-OFDM） systems are investi- gated. The purpose of our research is to counteract the impacts of laser phase noise and fiber nonlinearity. We propose two ICI self-cancellation-based CO-OFDM schemes, and adopt a pilot-aided decision feedback （DFB） loop for CPE compensation. The proposed schemes are compared with conventional CO-OFDM schemes at the same spectral efficiency. Simulations show that our schemes can not only enhance laser linewidth tolerance of the CO-OFDM system, but also present strong robustness against fiber nonlinearity.
Orthogonal frequency division multiplexing-passive optical network （OFDM-PON） and single-carrier fre- quency division multiplexing （SCFDM）-PON are promising solutions for future high-speed PON-based access. A polarization division multiplexing scheme with direct detection is proposed for OFDM-PON to effectively reduce bandwidth requirements for components. However, the scheme strictly requires spec- trum overlapping of two orthogonal sidebands and the 4 × 4 multi-input-multi-output （MIMO） algorithm to eliminate complex cross-polarization interference. In this letter, we propose a polarization interleaving （PI） approach that significantly reduces bandwidth requirements for optical and electrical components while achieving a high-flexibility and low-complexity MIMO algorithm. Downstream single sideband PI-SCFDM transmission is experimentally demonstrated.
