Wu Qiong, Feng Zhenhua, Tang Ming, Li Xiang, Luo Ming, Zhou Huibin, Fu Songnian, Liu Deming
Wuhan National Lab for Optoelectronics (WNLO) & National Engineering Laboratory for Next Generation Internet Access System, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China.
State Key Laboratory of Optical Communication Technologies and Networks, Wuhan Research Institute of Post and Telecommunication, Wuhan, 430074, Hubei, China.
Sci Rep. 2018 Oct 25;8(1):15827. doi: 10.1038/s41598-018-34212-1.
Capacity is the eternal pursuit for communication systems due to the overwhelming demand of bandwidth hungry applications. As the backbone infrastructure of modern communication networks, the optical fiber transmission system undergoes a significant capacity growth over decades by exploiting available physical dimensions (time, frequency, quadrature, polarization and space) of the optical carrier for multiplexing. For each dimension, stringent orthogonality must be guaranteed for perfect separation of independent multiplexed signals. To catch up with the ever-increasing capacity requirement, it is therefore interesting and important to develop new multiplexing methodologies relaxing the orthogonal constraint thus achieving better spectral efficiency and more flexibility of frequency reuse. Inspired by the idea of non-orthogonal multiple access (NOMA) scheme, here we propose a digital domain power division multiplexed (PDM) transmission technology which is fully compatible with current dual polarization (DP) coherent optical communication system. The coherent optical orthogonal frequency division multiplexing (CO-OFDM) modulation has been employed owing to its great superiority on high spectral efficiency, flexible coding, ease of channel estimation and robustness against fiber dispersion. And a PDM-DP-CO-OFDM system has been theoretically and experimentally demonstrated with 100 Gb/s wavelength division multiplexing (WDM) transmission over 1440 km standard single mode fibers (SSMFs).
由于对带宽需求极大的应用的压倒性需求，容量一直是通信系统永恒的追求目标。作为现代通信网络的骨干基础设施，光纤传输系统在过去几十年里通过利用光载波的可用物理维度（时间、频率、正交、偏振和空间）进行复用，实现了显著的容量增长。对于每个维度，必须保证严格的正交性，以便完美分离独立的复用信号。为了跟上不断增长的容量需求，因此开发新的复用方法，放宽正交约束，从而实现更高的频谱效率和更灵活的频率复用，是有趣且重要的。受非正交多址接入（NOMA）方案理念的启发，在此我们提出一种数字域功率分配复用（PDM）传输技术，该技术与当前的双偏振（DP）相干光通信系统完全兼容。由于相干光正交频分复用（CO-OFDM）调制在高频谱效率、灵活编码、易于信道估计以及对光纤色散的鲁棒性方面具有巨大优势，因此采用了该调制方式。并且，一个PDM-DP-CO-OFDM系统已在理论和实验上得到验证，可在1440公里标准单模光纤（SSMF）上实现100 Gb/s波分复用（WDM）传输。
