Dong Fang, Chen Guangqiu, Liu Zheqi, Lin Peng, Zhang Ying, Ma Wanzhuo, Wang Tianshu, Liu Zhi
Appl Opt. 2020 Dec 20;59(36):11389-11395. doi: 10.1364/AO.411962.
We experimentally demonstrate Nyquist wavelength-division-multiplexed (WDM) channels with a low signal-to-noise ratio (SNR) difference based on flat electro-optic combs (EOCs), which reduce the interchannel crosstalk penalty in Nyquist-WDM transmission with no guard band. The five Nyquist-WDM channels are generated through the insertion of uniform and coherent lines around each line of the EOCs from a dual-parallel Mach-Zehnder modulator. For the five channels, the normalized root-mean-square error of optical sinc-shaped pulses at a repetition rate of 9 GHz is between 1.23% and 2.04%. The SNRs of the Nyquist signal can be better than 30 dB by using flat EOCs with a narrow linewidth as WDM sources, and the difference in SNR is less than 0.6 dB for the WDM channels. The transmission performance of five Nyquist-WDM channels with no guard band is compared in a 56 km fiber link. The results show that our scheme provides a minimum interchannel sensitivity penalty of 0.7 dB at the forward-error-correction limit. The Nyquist-WDM channels with low SNR difference can effectively improve the communication performance of the Nyquist-WDM system.
我们基于平面电光梳（EOC）通过实验证明了具有低信噪比（SNR）差异的奈奎斯特波分复用（WDM）信道，这在没有保护带的奈奎斯特WDM传输中降低了信道间串扰代价。五个奈奎斯特WDM信道是通过在来自双并行马赫-曾德尔调制器的EOC的每条线周围插入均匀且相干的线来生成的。对于这五个信道，在9 GHz重复率下光学 sinc 形脉冲的归一化均方根误差在1.23%至2.04%之间。通过使用具有窄线宽的平面EOC作为WDM源，奈奎斯特信号的SNR可以优于30 dB，并且对于WDM信道，SNR差异小于0.6 dB。在56 km光纤链路中比较了五个无保护带的奈奎斯特WDM信道的传输性能。结果表明，我们的方案在前向纠错极限下提供了最低0.7 dB的信道间灵敏度代价。具有低SNR差异的奈奎斯特WDM信道可以有效提高奈奎斯特WDM系统的通信性能。
