余建军

采用先进的数字信号处理（DSP）技术，在发射机和接收机分别引入预处理和后处理，以提高光接入网络的频谱效率并延长传输距离。研究了一种基于光超奈奎斯特（Super-Nyquist）滤波的类9状态正交振幅调制（9QAM）信号多模均衡（MMEQ）后端DSP算法，使用这种方案，能够有效提高频谱效率，实现了频谱效率高达4 bps/Hz的正交移相键控（QPSK）信号传输；还研究了一种基于数字Super-Nyquist信号前端预处理的方案，此方案的优点是不需要光预滤波即可达到相同的频谱效率。使用一个采用直接调制激光器（DML）、直接探测和数字均衡技术的高速无载波幅度相位-64状态正交振幅调制（CAP-64QAM）系统，在20 km标准单模光纤（SSMF）上实现了创纪录的60 Gbit/s CAP-64QAM信号传输；使用相干探测，实现了速率高达100 Gbit/s的64状态正交振幅调制-正交频分复用（16QAM-OFDM）实时传输系统，解决了实时OFDM信号处理中的关键问题。

数字信号处理；高频谱效率；超奈奎斯特；相干光传输

In this paper， we investigate advanced digital signal processing （DSP） at the transmitter or receiver side for signal pre-equalization and post-equalization in order to improve the spectrum efficiency （SE） and transmission distance in an optical access network. A novel DSP scheme for this optical super-Nyquist filtering 9 QAM like signals based on multi-modulus equalization without post filter are proposed and experimentally demonstrated， which directly recovers the Nyquist filtered QPSK to a 9-QAM-like signal. With this technique， SE can be increased to 4 bits/s/Hz for QPSK signals. A novel digital super-Nyquist signal generation scheme is also proposed to further suppress the Nyquist signal bandwidth and reduce channel crosstalk without using optical pre-filtering. Only optical couplers are needed for super-Nyquist WDM multiplexing. We extend the DSP for short-haul optical transmission networks by using high-order QAMs. We propose and experimentally demonstrate a high-speed CAP-64 QAM system using direct modulation laser based on direct detection and digital equalization. Decision-directed least mean square is used to equalize the CAP-64QAM. Using this scheme， we generate and transmit up to 60 Gbit/s CAP-64QAM over 20 km stand single-mode fiber based on the DML and direct detection. Finally， several key problems are solved for real time OFDM signal transmission and processing. Using coherent detection， up to 100 Gbit/s 16 QAM-OFDM real-time transmission is realized.

digital signal processing； high spectrum efficiency； super-Nyquist； coherent optical transmission

在长距离骨干网及短距离接入网中，随着云计算、社交媒体和移动数据业务的迅速发展，因特网和个人业务的带宽需求以每年30%到60%的速度持续增长。业务带宽的增长趋势与降低单位比特成本的需求相结合，更加突显了高速光传输接口和高频谱效率技术的重要性。以速率为100 Gbit/s的长距离系统为例，将单载波偏振复用的正交相位键控（PDM-QPSK）调制格式与相干探测的数字信号处理技术（DSP）相结合，已经被证明是一种成功的解决方案。另一方面，能够提供高频谱效率传输的技术也被广泛研究，并可归结为两个主要方向，即降低频谱带宽需求以及增加调制阶数。……