Open AccessTransmitter skew tolerance and spectral efficiency tradeoff in high baud-rate QAM optical communication systems
Author(s) -
Yang Yue,
Qiang Wang,
Jon Anderson
Publication year - 2018
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.26.015045
Subject(s) - baud , quadrature amplitude modulation , qam , skew , spectral efficiency , optics , pulse shaping , computer science , residual , wavelength division multiplexing , transmitter , bandwidth (computing) , electronic engineering , optical communication , physics , telecommunications , bit error rate , channel (broadcasting) , engineering , transmission (telecommunications) , laser , algorithm , wavelength
Residual IQ skew in a coherent transmitter severely degrades the performance of long-haul coherent optical communication systems. The impairment is particularly detrimental for a high baud-rate system using quadrature amplitude modulation (QAM). Furthermore, Nyquist pulse shaping increases the spectral efficiency for WDM systems. However, sharp roll-off of Nyquist pulse shaping further reduces the tolerance to residual IQ skew. Thus, certain trade-offs between spectral efficiency and roll-off factor should be made to improve the tolerance of residual IQ skew. We experimentally studied this trade-off and determined the optimal roll-off factor, channel spacing, receiver bandwidth, and equalizer length. The results serve as a guideline for high baud-rate coherent WDM systems.