Open AccessExperimental demonstration of iterative post-equalization algorithm for 375-Gbaud PM-16QAM quad-carrier Terabit superchannel
Author(s) -
Zhensheng Jia,
HungChang Chien,
Yi Cai,
Jianjun Yu,
Chengliang Zhang,
Junjie Li,
Yaoguang Ma,
Dongdong Shang,
Qi Zhang,
Shuai Shi,
Huitao Wang
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.002157
Subject(s) - quadrature amplitude modulation , equalization (audio) , terabit , spectral efficiency , optics , transmission (telecommunications) , pulse shaping , intersymbol interference , computer science , bit error rate , electronic engineering , optical filter , qam , symbol rate , interference (communication) , physics , wavelength division multiplexing , channel (broadcasting) , telecommunications , wavelength , laser , engineering
We experimentally demonstrate a quad-carrier 1-Tb/s solution with 37.5-GBaud PM-16QAM signal over 37.5-GHz optical grid at 6.7 b/s/Hz net spectral efficiency. Digital Nyquist pulse shaping at the transmitter and post-equalization at the receiver are employed to mitigate the impairments of joint inter-symbol-interference (ISI) and inter-channel-interference (ICI) symbol degradation. The post-equalization algorithms consist of one sample/symbol based decision-directed least mean square (DD-LMS) adaptive filter, digital post filter and maximum likelihood sequence estimation (MLSE), and a positive iterative process among them. By combining these algorithms, the improvement as much as 4-dB OSNR (0.1nm) at SD-FEC limit (Q(2) = 6.25 corresponding to BER = 2.0e-2) is obtained when compared to no such post-equalization process, and transmission over 820-km EDFA-only standard single-mode fiber (SSMF) link is achieved for two 1.2-Tb/s signals with the averaged Q(2) factor larger than 6.5 dB for all sub-channels. Additionally, 50-GBaud 16QAM operating at 1.28 samples/symbol in a DAC is also investigated and successful transmission over 410-km SSMF link is achieved at 62.5-GHz optical grid.