Single-Lane 145 Gbit/s IM/DD Transmission With Faster-Than-Nyquist PAM4 Signaling

作者：Meng Xiang, Zhenping Xing, Eslam El‐Fiky, Mohamed Morsy-Osman, Qunbi Zhuge, David V. Plant · 发表于：IEEE Photonics Technology Letters · 年份：2018 · DOI：10.1109/lpt.2018.2841383 · 被引用次数：56 · 研究领域：Optical Network Technologies、PAPR reduction in OFDM、Advanced Wireless Communication Techniques

The performance of faster-than-Nyquist intensity modulation and direct detection (IM/DD) systems can be severely degraded by the inter-symbol interference (ISI) due to the component bandwidth limitation and the faster-than-Nyquist filtering. In addition, nonlinearities caused mainly by optical modulation and square-law detection can further deteriorate signal quality. Here, we propose to incorporate transmitter-side Tomlinson-Harashima precoding to mitigate the ISI and a Volterra nonlinear equalizer (VNLE) to mitigate the nonlinear distortions for PAM4 faster-than-Nyquist systems. We experimentally demonstrate a single wavelength 145 Gb/s PAM4 IM/DD transmission with bandwidth limited commercial components and sub-Nyquist sampling at 70 GSa/s. The optimal VNLE filter length is also investigated to balance the implementation complexity and system performance. In addition, compared with the scheme using transmitter-side duobinary precoding, receiver-side VNLE and maximum likelihood sequence estimation, both performance improvement and implementation complexity reduction are achieved.