Recent progress in short reach coherent communications

Next-generation data centre networks (DCNs) will likely demand per-carrier interface rates beyond 100 Gb/s to achieve the 800 Gb/s (even 1.6 Tb/s) after 2022, putting severe pressures to intensity modulation with direct detection (IM-DD). The coherent technology with high performance digital signal processing (DSP) has been proposed as a promising candidate. However, it is still widely regarded as too expensive and power hangry for DCN owing to the demand for narrow-linewidth lasers and complex DSP algorithms. In this talk, we will review recent progress on coherent technologies in short reach, including various simplified algorithm approaches. Special emphasis will be given to the self-homodyne coherent transmission with the aid of active polarization tracking enabled receiver. It has been demonstrated that significant complexity reduction (in power consumption and DSP module) can be achieved while keeping the spectral efficiency, both in offline and real-time high-speed experiments.