Abstract In this paper, we present the first experimental demonstration of inter-channel nonlinearity (NL) estimation with differential pilot (DP). This method has a simplified encoding structure of transmitter and low complexity. The distribution of different components in the received signal spectrum can be differentiated with Fast Fourier Transform (FFT), and the inter-channel NL power can be obtained by power subtraction. To verify the practicability of this method, a 25-GBaud coherent quadrature-phase-shift-keying (QPSK) wavelength division multiplexing (WDM) experiment system is employed with the launch power of 0–10 dBm per channel over 900-km standard single-mode fiber (SSMF). The results demonstrate that the inter-channel NL power estimation error is less than 1.5 dB when launch power is larger than 4 dBm per channel. Therefore, this method has good practicability for the inter-channel NL power estimation of coherent WDM systems.

中文翻译：

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差分导频信道间非线性功率的实验估计

摘要 在本文中，我们首次展示了使用差分导频 (DP) 进行通道间非线性 (NL) 估计的实验演示。该方法具有简化的发射机编码结构和低复杂度。接收信号频谱中不同分量的分布可以通过快速傅立叶变换（FFT）进行微分，通过功率相减得到信道间NL功率。为了验证该方法的实用性，采用 25 GBaud 相干正交相移键控 (QPSK) 波分复用 (WDM) 实验系统，发射功率为每通道 0–10 dBm，超过 900 公里标准单模光纤 (SSMF)。结果表明，当每个通道的发射功率大于 4 dBm 时，通道间 NL 功率估计误差小于 1.5 dB。所以，