We experimentally propose and demonstrate homodyne coherent detection in a short-distance data center interconnect with bidirectional fiber transmission. The transmitter in the proposed system sends the modulated signal and a continuous wave (CW) tone originating from the same laser diode (LD) over the 2 lanes of a duplex fiber to the remote receiver for coherent detection. Thus, this system allows the use of an uncooled LD with a large linewidth and reduces the complexity of digital signal processing (DSP) compared to that in a classical coherent system. A successful real-time demonstration with 600-Gb/s DP-64QAM using uncooled large-linewidth DFB lasers is conducted. Automatic stabilization against polarization fluctuations of the transmitted tone is achieved by the proposed polarization-tracking integrated coherent receiver in compact silicon photonics (SiP), tracking up to 300 rad/s without a performance penalty. The phase noise caused by mismatch and the link loss budget limitations are discussed and analyzed. This study shows that the proposed system is a potentially attractive solution for future 800G and 1.6T intra-data-center optical interconnects.

中文翻译：

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下一代数据中心互连的零差相干双向传输实时演示


我们通过实验提出并演示了双向光纤传输的短距离数据中心互连中的零差相干检测。所提出系统中的发射器将调制信号和源自同一激光二极管 (LD) 的连续波 (CW) 音调通过双工光纤的 2 个通道发送到远程接收器以进行相干检测。因此，与经典相干系统相比，该系统允许使用具有大线宽的非冷却 LD，并降低了数字信号处理 (DSP) 的复杂性。使用非制冷大线宽 DFB 激光器成功进行了 600 Gb/s DP-64QAM 实时演示。所提出的紧凑型硅光子学 (SiP) 中的偏振跟踪集成相干接收器可自动稳定传输音调的偏振波动，跟踪速度高达 300 rad/s，且不会影响性能。讨论并分析了失配引起的相位噪声和链路损耗预算限制。这项研究表明，所提出的系统对于未来 800G 和 1.6T 数据中心内光互连来说是一个具有潜在吸引力的解决方案。