In this Letter, we experimentally demonstrate a 1550-nm direct modulation laser (DML)-based dual-band Nyquist PAM-4 intensity modulation direct detection (IMDD) system using a real-time field programmable gate array (FPGA)-based receiver. Although the sampling rate of the analog-to-digital converter (ADC) used in the receiver is only 5-GSa/s and there is no mixer at the receiver side, the system can successfully realize 22-km SSMF transmission with 20-Gb/s data rate by using super-Nyquist sampling technique. To our knowledge, this is the first experimental demonstration of non-single-band signal transmission over IMDD system based on super-Nyquist sampling technique. In addition, power weighting technique is also applied in the system. The experimental results show that with the help of power weighting technique, the BER of the system can be reduced from $6.1\times {10}^{-3}$ to $2.6\times {10}^{-3}$.

中文翻译：

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使用超奈奎斯特采样技术在短距离IMDD系统上进行20 Gb / s双频带奈奎斯特PAM-4传输的实验演示

在这封信中，我们通过实验演示了基于1550 nm直接调制激光器（DML）的双波段Nyquist PAM-4强度调制直接检测（IMDD）系统，该系统使用基于实时现场可编程门阵列（FPGA）的接收器。尽管接收器中使用的模数转换器（ADC）的采样率仅为5-GSa / s，并且接收器侧没有混频器，但系统可以成功实现20-Gb的22 km SSMF传输/ s数据速率，使用超级奈奎斯特采样技术。据我们所知，这是基于超级奈奎斯特采样技术在IMDD系统上进行非单频带信号传输的第一个实验演示。另外，功率加权技术也被应用在系统中。实验结果表明，借助功率加权技术，$6.1\times {10}^{-3}$ 到 $2.6\times {10}^{-3}$。