Direct detection (DD) is one of the most attractive solutions for short and medium reach optical fiber transmission in comprehensive consideration of digital signal processing (DSP), power consumption, and cost. Various single side band (SSB) DD techniques have been widely investigated to detect and process the complex signal. In this paper, we propose a novel approach which uses only high-speed digital input/outputs (IO) to generate both quadrature phase shift keying (QPSK) signal and virtual carrier signal. A transmission of 4 × 32 Gb/s QPSK signal over 1200-km standard single mode fiber (SSMF) in block-wise manner has been successfully demonstrated. Only a single polarization in-phase-and-quadrature (IQ) modulator and one single photodiode (PD) are used for each channel. Compared with conventional DSP of coherent detection, the DSP in the proposed scheme is also simplified that only fixed frequency compensation is required without additional phase noise elimination. The overall system complexity has been greatly reduced.

中文翻译：

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基于Delta-Sigma虚拟载波生成的4×32-Gbps Block-Wise QPSK 1200-km SSMF直接检测传输

综合考虑数字信号处理（DSP）、功耗和成本，直接检测（DD）是中短距离光纤传输最具吸引力的解决方案之一。已经广泛研究了各种单边带 (SSB) DD 技术来检测和处理复杂信号。在本文中，我们提出了一种新方法，该方法仅使用高速数字输入/输出 (IO) 来生成正交相移键控 (QPSK) 信号和虚拟载波信号。已经成功演示了 4 × 32 Gb/s QPSK 信号在 1200 公里标准单模光纤 (SSMF) 上以块方式传输。每个通道仅使用一个偏振同相正交 (IQ) 调制器和一个光电二极管 (PD)。与传统的相干检测DSP相比，所提出方案中的DSP也被简化，只需要固定频率补偿而不需要额外的相位噪声消除。整个系统的复杂性已大大降低。