Wavelength-division multiplexing passive optical network (WDM-PON) is considered as a mainstream solution for 5G fronthaul transmission system to cope with the rapidly increasing bandwidth demand. In such a multi-wavelength system, nonlinear effects limit the achievable transmission distance and channel capacity. Therefore, in this paper, the impact of nonlinear effects on a multi-wavelength transmission system with 25 Gb/s/λ non-return-to-zero (NRZ) and a 200-GHz channel spacing over 25 km standard single-mode fiber (SSMF) is investigated through experiment and simulation. The effects of four-wavelength mixing (FWM) in O-band as well as cross-phase modulation (XPM) in C-band are both studied and discussed. Experiments are performed for 3- and 4-channel transmission cases, while 12-channel transmission is performed by simulation. The results show that in the O-band scenario, the FWM effect severely affects the performance of the channels near the zero-dispersion wavelength. Besides, the XPM products overlap the signal in the C-band, which also degrades the sensitivity. Based on these analyses, the nonlinear effects should be fully considered when planning wavelengths for 5G fronthaul transmission, including wavelength distribution and channel spacing selection.

波分复用无源光网络（WDM-PON）被认为是5G前传传输系统的主流解决方案，以应对快速增长的带宽需求。在这样的多波长系统中，非线性效应限制了可实现的传输距离和信道容量。因此，在本文中，非线性效应对具有 25 Gb/s/λ 不归零 (NRZ) 和 200 GHz 信道间隔的多波长传输系统的影响超过 25 公里标准单模光纤(SSMF) 通过实验和模拟进行研究。研究和讨论了 O 波段中的四波长混频 (FWM) 以及 C 波段中的交叉相位调制 (XPM) 的影响。实验是针对 3 通道和 4 通道传输的情况进行的，而 12 通道传输是通过模拟进行的。结果表明，在 O 波段场景中，FWM 效应严重影响了零色散波长附近信道的性能。此外，XPM 产物与 C 波段的信号重叠，这也会降低灵敏度。基于这些分析，在规划5G前传传输波长时应充分考虑非线性效应，包括波长分布和信道间隔选择。