We investigate the performance of a phase noise cancellation proposal to overcome the inherent laser linewidth limitation that acts as a key limiting factor in realizing digital signal processing (DSP)-based optical coherent access systems. The proposed cancellation algorithm is evaluated and analyzed through both extensive simulations and experimental studies on coherent 20-Gbit/s quadrature phase-shift keying (QPSK) signals. The use of polarization control based on the constant modulus algorithm (CMA) eliminates the polarization interference, which is a primary factor impacting the cancellation of random phase noise. A unique polarization control scheme with asymmetric CMA is proposed in order to remove the singularity issue created by the standard CMA. Its performance is verified in simulations and experiments. Through experiments that emulate laser linewidth by a phase modulator, it is confirmed that the cancellation algorithm overcomes the inherent limitation on laser linewidth.

中文翻译：

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非对称 CMA 相位噪声消除性能分析，用于实现经济实惠的相干 PON 收发器

我们研究了相位噪声消除方案的性能，以克服固有的激光线宽限制，该限制是实现基于数字信号处理 (DSP) 的光相干接入系统的关键限制因素。通过对相干 20-Gbit/s 正交相移键控 (QPSK) 信号的广泛模拟和实验研究，对所提出的消除算法进行了评估和分析。基于恒模算法（CMA）的极化控制的使用消除了极化干扰，这是影响随机相位噪声消除的主要因素。提出了一种具有非对称 CMA 的独特偏振控制方案，以消除标准 CMA 造成的奇异性问题。其性能在模拟和实验中得到验证。