We experimentally demonstrate a high-speed intensity modulation and direct-detection (IM/DD) system with four wavelength division multiplexing (WDM) channels. With the aid of semiconductor optical amplifier (SOA) and probabilistic shaping (PS) technique, 1T (280Gbit/ $\text{s}\times 4$ ) PS-PAM8 signals can be successfully transmitted over 40-km standard single mode fiber (SSMF). As a more precise performance criteria, the normalized generalized mutual information (NGMI) should be used to report the performance of PS shaped signals. In this experiment, each WDM channel can support 280Gbit/s/channel PS-PAM8 signals transmission with a NGMI larger than the threshold of a soft-decision forward error correction (SD-FEC) code of 0.83. Considering 25% FEC overhead, the net bit rate of each WDM channel is 220Gbit/s/channel. Therefore, the net transmission rate of the WDM system is 880Gbit/s, which can support the demand of 800G data connection. To the best of our knowledge, it is the first time to realize over 1Tbit/s PAM signal transmission over 40km in a four-lane IM/DD system.

中文翻译：

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四通道 IM/DD 系统中的高速 PS-PAM8 传输，在 O 频段使用 SOA 用于 800G DCI

我们通过实验证明了具有四个波分复用 (WDM) 通道的高速强度调制和直接检测 (IM/DD) 系统。借助半导体光放大器（SOA）和概率整形（PS）技术，1T（280Gbit/$\text{s}\times 4$）PS-PAM8信号可以在40公里标准单模光纤上成功传输（ SSMF）。作为更精确的性能标准，应使用归一化广义互信息 (NGMI) 来报告 PS 整形信号的性能。在本实验中，每个WDM通道可以支持280Gbit/s/通道的PS-PAM8信号传输，NGMI大于0.83的软判决前向纠错（SD-FEC）码的阈值。考虑25%的FEC开销，每个WDM通道的净比特率为220Gbit/s/通道。所以，WDM系统净传输速率为880Gbit/s，可支持800G数据连接需求。据我们所知，这是首次在四通道IM/DD系统中实现超过1Tbit/s的PAM信号传输超过40​​km。