We propose and demonstrate the asymmetric direct detection (ADD) of polarization division multiplexed single-sideband (PDM-SSB) signals with orthogonal offset carriers. ADD exploits the photocurrent difference to eliminate the Y-Pol interference in the X-Pol, and the X-Pol signal intensity to eliminate the X-Pol interference in the Y-Pol without resorting to iterative algorithms. This enables not only low-complexity signal linearization but also a simplified receiver front-end composed of a single optical filter, two single-ended photodiodes and two analog-to-digital converters (ADC). In the experiment, we first perform a parametric study of the proposed scheme at 40 Gbaud in the back-to-back configuration (B2B) to evaluate the performance impact of different system parameters including the carrier to signal power ratio (CSPR), the matched filter roll-off, and the filter guard band. Next, we demonstrate the transmission of 416 Gbit/s PDM 16-QAM signal over 80 km single-mode fiber (SMF) below the soft-decision forward error correction (SD-FEC) threshold of 2×10-2. We also numerically study the effectiveness of a 2×2 multiple-input-multiple-output MIMO equalizer in alleviating the inter-polarization linear crosstalk resulting from the non-orthogonal PDM-SSB signals due to polarization-dependent loss (PDL), which is not negligible for potential on-chip implementation of ADD.

中文翻译：

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正交偏移载波的非对称直接检测辅助偏振复用的单边带信号。

我们提出并证明了具有正交偏移载波的偏振分复用单边带（PDM-SSB）信号的非对称直接检测（ADD）。ADD利用光电流差消除X-Pol中的Y-Pol干扰，并利用X-Pol信号强度消除Y-Pol中的X-Pol干扰，而无需采用迭代算法。这不仅可以实现低复杂度的信号线性化，而且还可以简化由单个光学滤波器，两个单端光电二极管和两个模数转换器（ADC）组成的接收器前端。在实验中，我们首先以背对背配置（B2B）对40 Gbaud的拟议方案进行参数研究，以评估包括载波对信号功率比（CSPR）在内的不同系统参数对性能的影响，匹配的滤波器滚降和滤波器保护带。接下来，我们演示了在低于2×10-2的软判决前向纠错（SD-FEC）阈值的80 km单模光纤（SMF）上传输416 Gbit / s PDM 16-QAM信号的过程。我们还数值研究了2×2多输入多输出MIMO均衡器在缓解由于偏振相关损耗（PDL）引起的非正交PDM-SSB信号引起的偏振间线性串扰方面的有效性，即对于潜在的片上ADD实施而言，微不足道。