The performance of high-speed intensity-modulation (IM)/direct-detection (DD) system implemented by using O-band directly modulated laser (DML) could be limited by the waveform distortions induced by nonlinear modulation dynamics of DML. The conventional polynomial nonlinear equalizer (PNLE) can be used at the receiver to compensate for such waveform distortions. However, this nonlinear equalizer suffers from high implementation complexity. In this letter, we propose nonlinear equalizers based on the absolute operation for IM/DD system using DML. We replace the square operation in PNLE with the absolute operation to lower the implementation complexity. The effectiveness of the proposed equalizers is evaluated over 100-Gb/s 4-ary pulse amplitude modulation transmission system implemented by using 1.31- $\mu \text{m}$ DMLs. The results show that the proposed equalizers perform similar to the PNLEs, but lower the implementation complexity.

中文翻译：

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使用DML的IM/DD系统基于绝对操作的非线性均衡器

通过使用 O 波段直接调制激光器 (DML) 实现的高速强度调制 (IM)/直接检测 (DD) 系统的性能可能受到 DML 非线性调制动力学引起的波形失真的限制。传统的多项式非线性均衡器 (PNLE) 可用于接收器以补偿此类​​波形失真。然而，这种非线性均衡器的实现复杂度很高。在这封信中，我们为使用 DML 的 IM/DD 系统提出了基于绝对操作的非线性均衡器。我们将 PNLE 中的平方运算替换为绝对运算以降低实现复杂度。在使用 1.31-$\mu\text{m}$ DML 实现的 100-Gb/s 4 进制脉冲幅度调制传输系统上评估了所提出的均衡器的有效性。